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World Poultry Disease Research Progress and poultry disease control strategy in China Time :2009-09-07 Source: Benwang editing Author: admin
Animal Husbandry Co., Ltd. Henan China Region Manager,
China's poultry industry continued to grow steadily for 20 consecutive years, made remarkable achievements as the world's poultry power. According to the Ministry of Agriculture statistics, in 2000 China's meat output reached 62.7 million tons, per capita consumption of 52kg. According to UN Food and Agriculture (FAO) statistics, in 2000 China's output of eggs to 22.16234 million tons, accounting for 41.9% of world output, including eggs, 18.86 million tons, accounting for 85% of total output, per capita amounted to 17.7kg , total output and per capita volume ranking first in the world. Since reform and opening, eggs an average annual growth rate of 13.5%.
However, the poultry disease has been plaguing China's poultry industry, one of the key issues. At present there are about 80 kinds of China's poultry disease, which accounted for 75% of infectious diseases, resulting in enormous economic losses, has become a constraining bottleneck in the development of China's poultry industry. The survival rate of China's poultry is not high, with an average mortality rate of about 20% compared with developed countries, to more than one times the estimated average annual loss of poultry deaths in our country billions of dollars of production performance degradation caused by the disease, prevention and control expenses and other losses are more serious. Information shows that China's average per bird feeding vaccines and drug costs for the United States 10 times.
This shows that China's poultry disease prevention and treatment as compared with the world's developed countries, there are still gaps in today's accession to WTO, China's poultry disease prevention and control is only as quickly as possible with international standards, establish an effective operation in line with our actual control strategies and measures can we truly make our poultry industry in the world. This paper introduces the research progress of the world's avian diseases, and to talk about China's poultry disease prevention and control strategies for shallow understanding.
1, the World Poultry Disease Research Progress
(A) important viral diseases research
1. Avian Influenza (Avian influenza, AI) avian influenza virus (AIV) is a Orthomyxoviruses Division, with 8 segments minus-strand RNA, encoding 10 proteins, which includes: haemagglutinin (HA), neuraminidase (NA) , matrix protein (M) and nucleoprotein (NP) and so on. According to HA (9 species) and NA (15 species) of different proteins, AIV is divided into several serotypes. Although the frequency of bird flu than Newcastle high, but it will enable the infected flocks with high mortality rates, and even the whole group was lost to human health are also under greater threat, therefore, cause for concern.
AIV based on the strength of the chicken pathogenicity, avian influenza virus can be divided into two categories: low pathogenic avian influenza virus (LPAIV) and the highly pathogenic avian influenza virus (HPAIV). LPAIV the general performance of chickens infected with low mortality rates, accompanied by drop in egg production and minor respiratory symptoms, with mixed infection with other viruses or bacteria, the flocks may appear high mortality rate and most of the organ tissue lesions. On the contrary, HPAIV then produce high lethality, resulting in severe multi-organ infection in poultry in vivo, the mortality rate of up to 100%, and even endanger human health.
1.1 low pathogenic avian influenza in 2000, the United States in southern California, there are 10 commercial laying farms in the outbreak of low pathogenic avian influenza H6N2 type, 2001, there are still three flocks to detect AIV subtype H6 antibodies, but not isolated the virus. In early 2002, H6N2 in the central region of California commodities chicken, turkey and egg transmission.
In July 2002, in South Africa hens laying grower and meat kinds of egg drop occurs in chickens (about 50%), the mortality rate increased (about 20%), taking the organization of infected birds for virus isolation, by the agar immunodiffusion experiments, RT-PCR and serum typing proved to be H6N2 subtype LPAIV. 2002 in northern Italy, the outbreak of H7N3-type LPAI, seriously affected the export of poultry products.
In Asia the low pathogenic H9N2 more virulent, leading to high mortality rate occurred in chickens (10% ~ 80%) and reduced production performance. Isolated from diseased chickens to the H9N2 does not kill embryos in experiments, but also with the standard strain genome sequence comparison, homology is high. At the same time isolated from the diseased chickens also other respiratory pathogens: IBV, NDV, TRT, ORT, MG, MS, E. coli and so on, studies suggest that: two or more of the pathogenic infection is a collaborative LPAIV (H9N2) caused high mortality reasons, and no variations in virulence. However, the existing problems are: the use of H9N2 isolated from the production of oil-emulsion inactivated vaccine can effectively prevent a large number of chickens died, but did not prevent the drop in egg production in chickens, while China is not the case, the use of H9N2 oil production emulsion inactivated vaccine can effectively prevent the occurrence of H9N2 AI in chickens.
1.2 Highly pathogenic avian influenza in certain LPAIV (H6 and H7) in nature can be mutate into highly pathogenic strains, such as the United States (1983 ~ 1984), Mexico (1994 ~ 1995), Italy (1999 ~ 2002), Chile (2002). Some studies show that this change in virulence is due to avian influenza virus hemagglutinin HA gene and protection of sex-related cleavage site has changed (for some amino acid insertion) and caused by mutations of the genes and reported HPAIV environment in which genetically similar strains. 2002 Virginia 197 of the 4.7 million farms in the outbreak of H5N2 infection in poultry products.
Chile, in May 2001 took place LPAIV infection, isolated the H7N3 subtype virus isolated from a few weeks of the highly pathogenic strains. Through the low and high pathogenic H7N3 strain caused by the high of eight gene segments of the nucleotide sequence analysis, we found two more similar difference is that the highly pathogenic strain of the cleavage site of hemagglutinin gene of 30 nucleotide insertion, most likely two recombinant viruses generated.
1.3 Evolution of public health concerns from the animal point of view, the emergence of the avian flu virus than the human influenza virus early, so many scholars believe that a human influenza may be evolved from the avian flu, human influenza viruses and the emergence of pandemic strains of bird flu virus closely related. It was noted that a human influenza A 2 (H2N2) and A 3 (H3N2) subtype is likely to be human, avian flu virus through gene recombination came, it was also isolated from the flocks with people related to H1, H2, H3 subtypes of influenza viruses. Now widely recognized that cause human pandemic strain of a new subtype of influenza A virus, is directly or indirectly, by the people, the bird flu virus evolved by gene recombination. In August 1997, China's Hong Kong for the first time reported in 18 cases of H5N1 human infections of bird flu, of which 6 died, has aroused worldwide concern. After 1997, the world they have appeared in several avian influenza virus infection of human events. In February 2003, in our two cases of H5N1 occurred in Hong Kong's avian flu cases; 2003 2 to 7 months, 83 cases occurred in the Netherlands of avian influenza H7N7 human cases; in January 2004, the H5N1 in Vietnam suspicious persons cases of bird flu in the dead of the cases, five cases have been laboratory confirmed. In recent years, studies have shown that the avian influenza virus infection in human beings have three kinds of different subtypes. In 1996, in the United Kingdom from a woman suffering from conjunctivitis, the eyes of the duck in an H7N7 virus isolated. In 1997, in Hong Kong died from a child who isolated a virus, H5N1 subtype. In 1999, China's Hong Kong 2 1-year-old and 4-year-old girl in the isolated influenza rehabilitation of two separate strains of H9N2 subtype. Therefore, the experts say: highly pathogenic avian influenza virus, such as H5N1, H9N2, H7N7, etc. may result in the event of mutation of avian flu epidemic populations, suggesting the bird flu virus on humans have great potential threat.
1.4 Since the birds and wild waterfowl are the natural AIV storage host, then the eradication of the disease is difficult, even impossible. Must take steps to block poultry and wild waterfowl, direct or indirect contact, contact with prey (especially waterfowl) and people into the chicken coop before changing clothes and bathing. Vaccine and strict quarantine measures should be combined in order to control the commodity groups in chickens and turkeys, the occurrence of mild-type AIV. As for the virulent AIV infection, strict isolation and out of sick chickens to be effective measures. Many parts of the application of highly pathogenic avian influenza virus, inactivated vaccine has been paying off.
1.5 Prevention, control and fight OIE strategy for HPAI is classified as category A infectious disease, usually abroad, isolation, culling approach to risk areas, as the center to establish the immune quarantine area, slaughter of infected flocks, but this requires adequate financial compensation as a backing. For developing countries, at present, more and more people believe that vaccination should be included in HPAI control program, and isolation and quarantine, perfect combination of biosecurity and culling is a good way to control the disease. Vaccination is an important measure to eradicate this disease, due to the bird flu virus serotypes are many different subtypes of avian flu vaccine to protect a type-specific.
Focus on bio-safety is to reduce or avoid the key factor in chickens infected with AIV, such as strengthening farm (homes) and outside of the isolation and disinfection of vehicles and personnel between the strict disinfection to reduce the AIV by the tires, shoes, spread, decline of foreign personnel, attention to water and feed hygiene and so on.
2. NDV (Newcastle disease, ND) ND is a worldwide problem, is still against the majority of countries, especially developing countries, the poultry industry, the primary disease. According to statistics, in 2001 in 63 countries and territories reported that the disease occurs. From a global perspective, the NDV virulent than the highly pathogenic avian influenza reported to be much more. NDV is a paramyxovirus family, to have enveloped negative strand RNA virus, the virus genome mutations are sensitive, but because NDV genome is linear, so the speed variation than eight segments of avian influenza virus rapidly. Since NDV is only one serotype, therefore, different vaccine strains have some cross-protection.
Because the vaccine's widespread use of Newcastle disease in the world has been better control, but by low virulent Newcastle disease virus, egg-laying chickens caused by drop, mild respiratory symptoms and low mortality rates have occurred. Especially in recent years, highly virulent NDV in chickens caused by high mortality rates and a significant decline in egg production are still a number of countries reporting.
Due to the presence of avian influenza, Newcastle disease no longer has the diagnosis of clinical symptoms, diagnosis must be separated by pathogens. Studies suggest that in most parts of the outbreak of virulent Newcastle disease in chickens is due to poultry house environment, the existence of highly pathogenic NDV, is characterized by the F fusion protein on a particular site -113RXR/KR * F117-, not by low - Virulence conversion came. Newcastle disease virus variation remains a mystery, yet to be further confirmed.
Newcastle has been OIE classified as category A infectious disease of world trade have a greater impact, therefore, a good control measures is the study of hot spots. The use of live vaccine and inactivated vaccine against Newcastle disease on many occasions to strengthen the immune system can effectively prevent the occurrence of Newcastle disease, but this the one hand, an increase of vaccine costs, on the other hand are likely to flock will have a greater stress, so that their production performance. Vaccination can reduce the morbidity and mortality, relieve symptoms, reduce the virus in the body environment, the quantity, but the vaccine does not provide 100% protection, therefore, in order to better prevent the occurrence of Newcastle disease, but also should pay attention to bio - security.
3. Avian lung infection (Avian pneumoviruses infection) Avian Pneumovirus (APV) is a turkey rhinotracheitis (TRT) and chicken pathogenic lung infection in chickens after infection usually occurs swollen head syndrome (SHS). APV has occurred in Europe, Asia, South America and Central America, originally under the glycoprotein gene (G) the difference is only found in two serotype A and B, 1996 outbreak of the disease in the United States, and then matrix protein (M) and the fusion protein gene (F) difference found in a third serotype C, the recent French scholars in vivo isolated from duck to the fourth serotype D. APV infection in the United States, the first occurred in Colorado, Minnesota, after the near endemic, the place is a turkey breeding of high-density areas, C-type APV with human pneumonia virus A or B-type were similar.
Europe APV early research work focused on the development of the disease live vaccine and inactivated vaccines, in general, as long as the correct use of these vaccines, the effects were very good, and the two serotypes can be cross-protection. APV after the secondary infection of chickens infected with Mycoplasma gallisepticum and Escherichia coli will become very serious disease, and another, IBV virulent APV would interfere with the replication in the trachea, these two diseases the vaccines would interfere with each other, which indicates that vaccine Application of the importance of timing. Recent U.S. studies have shown that C-APV Newcastle disease virus on chicken will enhance virulence.
Recent studies have shown that wild birds in the spread of APV played a great role in APV and NDV and AIV may be the same as the host spectrum is broad, but it still needs further investigation.
4. Infectious bronchitis (Infectious bronchitis, IB) was a global distribution of infectious bronchitis. IBV's host range is narrow, it causes widespread with a high degree of infectious and local characteristics of the rapid spread within the scope of the. Some strains only in specific countries only. The persistence of IBV in chickens there are some features, but at present the significance of these features is unclear. IBV primarily caused by respiratory diseases, but other causes can lead to the spread of the disease, although the kidney-type strains can cause kidney lesions and death of chicks, but the conventional respiratory-type strain compared to the lesion is a focal proliferation of, and there is no so fast.
Essentially eliminate the current IB is not yet possible, but the existing vaccines can provide good control of the disease help. IBV S1 gene differences in the amino acid sequence led to the emergence of variant strains, these strains of antigenic variation with the existing vaccine strains different, but will occasionally pathogenic to strong and persistent, the need to develop new vaccines, such as the European The 793B strains, 4 / 91 and CR88 strains. Fortunately, not all variants have the need for new vaccines, laboratory and testing in the traditional cross-may be to clarify the relationship between IBV strains, from a practical point of view, and testing under the protection of sub-type ratio derived from serotype or the efficiency of genotyping vaccine more effective.
In recent years, the molecular structure of the IBV and have a deeper understanding of immune mechanisms, which will control the disease is very important. For example, recently successfully developed a full-length IBV infectious clone, this clone can be a more secure, would not return to strong specific vaccine, it can deal with variations in strains of IBV. Study found that the immune mechanism, IB's immune not just determined by S1 gene, IBV of the other components also play a role, this finding could explain why some vaccines can be a number of IB significantly different variant to provide protection.
On the other hand, IB recombinant vaccine research has been important progress. The use of different types of IBV strains of the S1 gene was prepared by genetic recombination between the recombinant virus, which represents the future of IB vaccine research focus and direction. U.S. scholars Beaudette as a receptor for the S1 gene of the S1 gene of M41 Preparation of Recombinant IBV, experimental results show that the immune effect of recombinant and M41 rather, better than Beaudette, but much lower than the toxicity of M41, is an extremely with the development of promising vaccines.
5. Infectious bursal disease (Infectious bursal disease, IBD) IBDV caused by immune suppression, the emergence of super-strain, antigen variation and genetic change has caused poultry disease experts from the world's attention. IBDV strain has become the brooding phase of super-serious harms to the disease.
At present, IBDV molecular diagnostics has entered a new phase, VP2 protein gene RT-PCR and RFLP, nucleotide sequence comparison analysis techniques are being perfected. In addition, breakthroughs in vaccine research, namely, super-drug for IBD vaccine IM (Irwin Moulthrop) has been attenuated by cell passaging obtained. Abroad, have been used as carrier pox virus and baculovirus expressed VP2 proteins, expression products of both can be used as diagnostic antigens, but also can be used as immunogens, that is, genetic engineering vaccine.
6. Infectious anemia (Chicken infectious anemia, CIA) CIAV is a round circular DNA viruses, no envelope. Broader epidemic, the main show latent infection, is generally not a separate disease, immune suppression is stronger, can lead to shrinkage of the thymus and other lymphoid organs. In Nigeria, an epidemiological survey of 180 sera, 80% of the serum samples were positive, indicating a high rate of infection. Survey showed that about 30% of the SPF chickens positive for the CIA, a greater threat to the SPF chickens. In our country the dangers of CIA is also relatively large.
The CIA progress in molecular diagnosis of pathogens present have been established to detect infected cells CIAV the PCR method, PCR test results and pathogen isolation the same result.
7. Marek's disease (Marek's disease, MD) in recent years, MDV virulence increased, and this is an indisputable fact. The 20th century, 60s, MD incidence of toxicity-based multi-medium; 70 years, due to turkey herpes virus vaccine (MD-3) popularity, the incidence gradually transformed into virulent strains (vMDV). In 1983, the U.S. price of seedlings emerged 2 (SB1 + HVT), the incidence of clinical strains evolve into super-toxic (vvMDV), routine vaccines ineffective. Liquid nitrogen stored MD-1 vaccine CVI988 (Rispens vaccine strain) is still the most effective vaccine.
MD vaccine genetically engineered vaccine is an important research direction. Glycoprotein B (gB) and other glycoprotein genes in fowl pox virus, HVT and MDV-induced weak virus vector has been expressed. These vector vaccines against Marek's disease induced protective immunity, but so far no one received a certificate to allow commercial use. Deletion mutant seedlings is to choose a strategy, but because there is not enough MDV genome, operational technology and has yet to be identified with the virus virulence genes that are directly related, so progress is slow. Meq gene deletion has been completed, but perhaps due to the strain of proliferation in the body are not well, so that the mutant not provide a high level of protection force. However, it is now mastered the creation of mutant strains of the new technology, which will facilitate the potential of new vaccines to study gene function.
8. J ALV (Avian leukosis subgroup J) in the past 10 years, ALV-J subgroup retroviruses has led to the worldwide broiler losses. Because the disease is vertical transmission and horizontal transmission, Europe, the United States, many of Yuanzhong Chang affected to different degrees of harm, caused widespread concern around the world, the disease has been put on the purification of an important agenda. Australia in connection with specific ELISA, SPF cell culture and RT-PCR and other laboratory means to purify the disease was divided into three stages of the disease eradicated. Professor Cui Zhizhong in China in the Chinese J subgroup ALV and reticulo-endothelial hyperplasia virus (REV) of mixed infection caused by immune suppression carried out in-depth study.
(B) food-borne bacterial diseases research
1. E. coli disease (Colibacillosis) E. coli in the environment of poor and other vulnerable secondary pathogen infection, In addition, E. coli infection, the body's respiratory mucosa and intestinal mucosa damage, easy secondary ND, IB, ILT and the MG and other diseases, so that flocks of elimination rate and mortality. E. coli is a normal intestinal bacteria, is divided into pathogenic and non-pathogenic nature of two kinds. American scholars in the incidence of E. coli isolated from chickens in the R plasmid on tsh, iucC and cvaC genes, and healthy chicken gut E. coli R plasmid without these genes. Of E. coli typing results showed that the major countries of the world are basically the same pathogenic E. coli, mainly O78, O2, and O1 and so on. However, Gao Song and so on from China's 18 provinces, municipalities and autonomous regions out of isolation and identification of avian Escherichia coli 595, a total of 440 identified isolates of serotype O, of which O18, O78, O2, O88, O11, O26, etc. 6 serotypes were the dominant serotypes.
Since E. coli is easy to produce on the use of antibiotic resistance; antibiotics drug residue on people's health have a greater hazard in which poultry products subject to trade restrictions; infected with E. coli, the chickens died Amoy rate increased, an increase in visceral waste , using bacteria to seedlings of the same serotype immunity only bacteria have better results, and thus to find effective preventive measures are all problems facing the poultry farm. Scholars at home and abroad dedicated to disease-causing genetic analysis of subunit vaccine (F11, FT, TT) research. In addition, since the poultry producing yellow-green body of toxins isolated from the O157: H7 E. coli has been changed in the past that the avian source of E. coli infection of human views. O157: H7 can lead to human beings, including asymptomatic infection, mild diarrhea, hemorrhagic colitis, hemolytic uremic syndrome and other clinical manifestations.
2. Salmonellosis (Salmonellosis) Avian Salmonella disease is one or more of the genus Salmonella Salmonella in poultry caused by acute or chronic infectious disease, is divided into pullorum disease, fowl typhoid and fowl paratyphoid. Of which can be caused by salmonella in poultry paratyphoid infection and the wide variety of animals, and therefore suffering from fowl paratyphoid poultry products are often caused human salmonella infections and food poisoning is one of the important reasons, often in Europe, America, Japan and other lead to serious social health problems, has also become difficult for China's exports of poultry meat and egg products one of the main. In addition, due to poultry production units for the control of poultry salmonellosis or purification and feeding a large number of drugs, often lead to severe drug-resistant strains, or a certain degree of drug residues also affect the international trade in poultry products. Recently, Salmonella enteritidis has been approved for use in inactivated vaccines. Association of British law requiring all poultry flocks must be vaccinated in this vaccine, In addition, an attenuated Salmonella Enteritidis vaccine immunization of drinking water has also been approved.
Relating to the classification of Salmonella have been improved, according to a new classification method, Salmonella is divided into two kinds, namely, S.enterica and S.bongori, more than 2,500 serotypes. Since the eighties from the last century, humans and animals, the prevalence of non-typhoid salmonella occurred in two major changes. First, the multi-drug resistant Salmonella typhimurium and its application in food animals, the emergence of groups in the dissemination of information; Second, as a major source of pathogens in eggs? The emergence and prevalence of Salmonella enteritidis.
3. Campylobacter jejuni disease (Campylobacteriosis) Campylobacter jejuni can cause many diseases occur in humans and animals, and is a food-borne pathogens, in a certain range of its food-borne bacterial infection caused by more than Salmonella, Campylobacter jejuni has been the safety of poultry products pose a serious threat. Bacteria not only cause human fever, acute enteritis, the reactive arthritis, Reiter's syndrome and Green? Barre syndrome, a disease characterized by autoimmune diseases can also cause hepatitis, turkey and blue crown diseases of broiler chicken and the chicken necrotizing hepatitis, chicks, calves, piglets, diarrhea and other diseases. In the United States each year by approximately 2.4 million cases of gastroenteritis caused by Campylobacter jejuni, accounting for 1% of the total population of a 2%. Contact or consumption of poultry products are considered the major route of transmission, according to surveys, 75% of the market for sale of live poultry and poultry meat contains 80% of Campylobacter. For more than 30 countries, surveys show that the mid-80 Campylobacter jejuni in chicken products have been widely distributed. Early scholars believe that the vertical transmission of bacteria can not occur, but recent studies have shown that there is a low level of vertical transmission of bacteria. According to another study confirmed that once the chicken cecal Campylobacter jejuni to settle these bacteria can be up to 8-week experimental period persists, and the chicken-derived strains after passage through chickens increased virulence. This shows that flocks of poultry are horizontal transmission of Campylobacter jejuni, long-term growth of contaminated poultry contaminated with the cause of the rising age.
PCR method using Campylobacter flaA gene fragments highly conserved sequence of SVR were amplified by fast detection of chicken feathers and egg shell or in the presence of Campylobacter in poultry meat.
Second, China's poultry disease control strategy for
(A) At present, the main features of China's poultry disease epidemic
1. More and more types of poultry disease, but most harmful infectious diseases, according to incomplete statistics, cause harm to the poultry industry has reached more than 80 kinds of disease, but with the largest number of infectious diseases, accounting for 75% of the total number of poultry disease above, it is estimated that China's annual poultry disease caused by various types of poultry, the mortality rate as high as 20% of the economic losses of billions of dollars.
2. An increased range of new cases emerging avian diseases in China mainly include: chicken infectious anemia, avian flu, different disease-type avian infectious bronchitis, infectious virus gonads gastritis, Muscovy duck parvovirus disease, chicken viral arthritis, production Egg drop syndrome, avian reticuloendothelial hyperplasia, J subgroup leukemia, ascites syndrome, and so on.
3. Pathogen mutation, clinical symptoms atypical of recent years, the incidence and prevalence in the poultry disease process, as some avian diseases pathogens occurred mutation, resulting in atypical of clinical symptoms. As the atypical is the most obvious example of Newcastle disease, infectious bursal disease virus and Marek's disease virus strains have emerged superior. Antigenic structure of mutation and serum-type variable, so that some vaccines prevention and control more difficult. Avian infectious bronchitis, previously endemic in our country mainly respiratory type, 90 years addicted to kidney-type emerged in recent years has emerged proventriculus type, making vaccine research has become increasingly difficult. If you are using the vaccine and epidemic strains of serotype inconsistent, often leads to vaccine failure. Another example is Marek's disease, in the 20th century, 70's, the wild strains are virulent mainly to the 80's, some countries of the super-drug, and 90 years in the United States and Europe have emerged super strains Each time the enhanced virulence of pandemic strains have led to failure of the existing vaccine. Foreseeable future, both in prevalence of poultry diseases, or disease-causing mechanism of the city on the increasing complexity of the requirements of our veterinary workers are increasingly high.
4. Drug-resistant bacteria become more serious and long-term due to the overuse of antibiotics and feed additives, adding low doses of antibiotics, leading to bacterial resistance is increasingly common, more serious, resulting in control of bacterial diseases become a major challenge. Zhi-Ming Pan, Jiao Xin and other pairs of 1962 to 1999 in some regions of Salmonella pullorum trends in drug resistance study found that bacterial resistance patterns over time and gradually widened until the late 90s, bacteria may be simultaneously 10 two kinds of antibiotic resistance.
5. Subclinical immunosuppressive diseases has become increasingly common multi-infection of a common immunosuppressive virus: Marek's disease virus, infectious bursal disease virus, Reticuloendotheliosis virus, chicken infectious anemia virus, reovirus Virus (infectious arthritis virus), chicken leukemia virus. Immunosuppressive viral infection hazards mainly as follows: to make viral and bacterial infections are not typical symptoms of disease; for specific immune response to vaccines, decline or lack of response (such as the HI low NDV), and secondary bacterial infection increased significantly. Because of immune suppression is difficult to diagnose viral infection has been neglected, together with a number of immunosuppressive virus infection in non-vaccine-preventable, and more emphasis on its hazards.
(B) the status quo of China's poultry disease prevention and control
1. Poultry disease prevention and control research in China made important progress in
1.1 Etiology of more in-depth in the use of conventional serological method of the basic characteristics of pathogens at the same time, in the pathogen's molecular biology have also been extensively studied. Such as the viral nucleic acid genome sequence or primary immunization of the original gene sequence determination, so that people can more clearly recognize pathogen occurred molecular basis of genetic variation, in order to predict the evolution of the disease has laid a foundation; encoding structural protein amino acid sequence of derivation, as the major immunogenic proteins to identify and carry out specific diagnostic reagents or genetically engineered vaccine provides a means and basis for such. So far, affecting the healthy development of China's poultry industry, the major diseases such as avian influenza, Newcastle disease, Mark Li's disease, infectious bursal disease, infectious bronchitis, etc. The main pathogenic gene sequence or its genome sequence has been determined , but also from the molecular level on some pathogens of wild strains and vaccine strains Differences between the structure of nucleic acids, which are evolution and development of disease revealed a certain degree of molecular genetic variation of the law. But on the whole, the pathogenicity of the pathogenic mechanism and the immune mechanism of the breadth and depth to be the development of molecular function of important pathogens are still not thorough enough, to track work the high side, originality, or too few features of the results.
1.2 Disease diagnosis technology developed rapidly serology, immunology, combined with clinical symptoms of pathological diagnostics techniques and methods to the entire poultry disease prevention and control is almost in-depth research, and some serological methods has developed into a preliminary diagnostic reagents (Box ), such as the University of Newcastle disease Yangzhou Virulent rapid ELISA diagnostic kit, Salmonella ELISA-PCR co-detection kit, as well as H5, H9 subtype of avian influenza virus rapid detection of multiple RT-PCR kits, etc.; Henan Academy of Agricultural Sciences IBD colloidal gold Diagnostic Kit; China Agricultural University, College of Veterinary Medicine of the lymphatic leukemia ELISA diagnostic reagents, Beijing Academy of Agriculture and Forestry Animal Husbandry and Veterinary Research Institute of Infectious rhinitis ELISA diagnostic reagents, etc., these preliminary diagnostic reagents (Kit) have greatly improved the speed of diagnosis, and convenient operation, high accuracy, for the commercialization of China's poultry disease diagnostic reagents opened the way for the development. But the poultry disease diagnostic studies, the emphasis on technology, the phenomenon of light products, universal, independent research and development of a real clinical need for new diagnostic reagents (box) not more than, not to mention the formation of brand products.
1.3 to accelerate the pace of new vaccines to protect the traditional vaccine production and the health of the poultry industry has played a huge role in the development of the current vaccine used in virtually all the major infectious diseases of poultry. However, with modern immunology, molecular biology techniques and the rapid development of the immune poultry disease prevention needs of practice, and new vaccines continue to emerge. Such as the recombinant virus vaccine, recombinant bacterial vaccine, gene deleted vaccines, multi-epitope vaccines could feed vaccines and DNA vaccines, these vaccines in laboratory studies and have a certain immunity effect, but how widely used in clinical practice is still a lot of work to be done, but it gives people in the vaccine research and development provides new ideas and thinking. It is noteworthy that the new vaccine research in empirical research model still accounts for a considerable proportion of the vaccine rational design of a new model has produced prototype, but the accumulation of a serious shortage of theories and technologies.
1.4 Disease mechanism of deepening the pathogenesis of the disease in poultry has been the focus of research on poultry, conventional methods from the sharp eyes and the cellular level, tissues and organs under the microscope to study and practice of Microbiology & Immunology to study the cellular level, with the molecular biology and the universal application of electron microscopy, so that poultry disease researchers from the molecular level on the mechanism of disease research. Research in this area, should the pathogen? Host interactions in the law will accomplish a great deal.
2. Poultry disease prevention and control of China's major problems
2.1 Non-standardized model of poultry, poultry production units in various forms of ownership, size Dazhong Xiao San coexist, facilities and technological level of high, low, simple as in, bio-security quarantine system is not perfect, vaccines, veterinary medicine, feed, misuse of a serious, leading to the disease is difficult control, the product can not meet the "high-quality, safe, pollution-free" in the pursuit of food consumption.
2.2 Import many diseases, such as EDS-76, J-AL, CIA, HPAI, RE and so on.
2.3 The flow of poultry and their products are not standardized for all the right to slaughter the Chinese goose, poultry and their products are not only the charges and quarantine, no quarantine, no charge, unauthorized sale, purchase, transport dead poultry and their products is widespread .
2.4 The legal system is not perfect in China and animal diseases and food safety-related laws, "Food Sanitation Law" (1983), "Infectious Diseases Prevention Law" (1989), "Import and Export Quarantine Law" (1989), "import and export of animals and plants Quarantine Law "(1992)," Animal Epidemic Prevention "(1998)," Veterinary Regulations "(1987)," feed and feed additives regulations "(1999), etc. Most of these laws and regulations based on legislative drafting department, with to a lot of drawbacks, and some are still many gaps in the law, some conflicting, some with international law does not converge, and some bad, and so operability.
2.5 Veterinary institutional problems in the present, the European Union on China's veterinary health management system to hold strong objection. If China's farming and export processing enterprises in the different departments in the implementation of veterinary health, veterinary supervision, including both the State animal husbandry and veterinary department of veterinary presence, there are entry-exit inspection and quarantine agencies as well as the enterprise's own veterinarian veterinarians. The EU clearly stated that only the national veterinary authorities to send veterinarians to the production and processing enterprises of poultry and their products to implement the legitimate veterinary health supervision, no other veterinary supervision of the legal qualifications. Because the entry-exit inspection and quarantine system of veterinary confined to port and export products, and can not cover all the livestock and poultry products, while the EU requires a company's products must all meet the veterinary hygiene standards in order to effectively guarantee the quality of the product exports to the EU in order to export to the EU , the same company's products can not be because of domestic, export of difference and the implementation of the different veterinary health regulatory procedures. In addition, the enterprise itself as an enterprise of the veterinary staff is serving the interests of the enterprise, its production process, inspection and quarantine work, can not represent the country's veterinary health regulatory procedures. The agricultural system within the city, county veterinary system is the set of disease prevention, quarantine, services, management, and supervision in one.
2.6 vaccines, veterinary drugs, feed production and sale of fake and shoddy products too. Too many small-scale duplication and form can not be together, brand-name products too little.
(3) China's poultry disease control strategies
Due to the above problem exists, poultry disease has constrained the development of our national poultry industry an important factor. With the intensification of China's poultry improvement in the level, if not do a good job poultry disease prevention and control work, poultry disease caused by direct or indirect losses will be even more serious. According to expert estimates, the size of flocks for each doubling of the incidence of the disease on the rise six-fold. Therefore, the rapid increase in China's poultry disease prevention and treatment as soon as possible with international standards has become imperative.
1. Strengthen the scientific research
1.1 to strengthen basic research using molecular biology tools, combined with conventional technology, an important molecular etiology of infectious diseases of poultry research, carried out analysis of the genetic structure of pathogenic microorganisms, the specific components of pathogenic microorganisms and toxins, surface antigens, such as genetic mapping, cloning and expression, analysis of their pathogenicity, Genetic variation, resistance mechanism, and the antigenicity of the active ingredient and animal pathogens in the laws of the interaction between body, which for a number of major infectious diseases (including the important zoonoses) in occurrence and development of process and control methods for the analysis of micro-biology studies. To identify the origin of infectious diseases and drug therapy target. Anti-sense nucleic acid technology, nucleic acid technology and bio-reactor technology research, to explore gene therapy, poultry and genetically modified disease-resistant breeding and disease prevention, application of protein production approach. Active immunization of poultry biology research, while improving on drug pharmacology and toxicology research on poultry physiology research, the study of parasites, to enhance the poisoning of poultry diseases, parasitic diseases, nutrition, metabolic diseases and other common diseases the control level. At present, the veterinary scientific research should be more concerned and resolve animal people Zoonosis of public health and food safety basic research.
1.2 to strengthen veterinary drugs and veterinary biological products, examine the use of chemical and biological engineering, new technologies, research and development of oligonucleotides, carbohydrates, peptides, proteins and other chemical synthetic antibacterial drugs and semi-synthetic antibiotics and a new hybrid antibiotics, to find good curative effect and low toxicity, pollution-free, inexpensive, easy to use anti-bacterial drugs. While strengthening the study of traditional Chinese herbal medicine to develop a quick, long-lasting, non-residue of traditional Chinese medicine preparation. Research and development of new antibiotics alternatives. Strengthen the veterinary biological products research. In the traditional vaccine research, the system should focus on vaccine strain selection and optimization of seedlings, tissue culture techniques and the protection of the vaccine agent, diluent, adjuvant, immune enhancer studies, thereby enhancing the immune effect of the vaccine, to reduce production costs and reduce the incidence of vaccine failure. In the new vaccine research, to speed up genetic engineering subunit vaccines, gene deletion or mutation of vaccines, live vector vaccines, DNA vaccines and genetically modified may be fed vaccines. Focus on non-pathogenic viruses and bacteria as a novel expression vector and transformation, and of sub-types are more pathogenic for multivalent subunit vaccine and multi-gene engineering vaccine of the research. In addition, according to China's existing research base, the use of immunology, serology and molecular biology approach to a variety of avian diseases fast, simple, accurate, sensitive and inexpensive diagnostic kit for the commercialization of research and development work.
1.3 to strengthen basic research in poultry disease epidemiology and disease monitoring system for the construction of epidemiological data collection is a long-term, daily work, disease monitoring system for the establishment and effective operation of the basic guarantee of this work. According to China's animal disease prevention and control of the actual needs of basic research should be strengthened epidemiological and form networks and systems.
2. Strengthen law enforcement, prevention, healthy avian diseases disease prevention system to prevent animal diseases from entering the prevalence of poultry diseases, in large part because of lax enforcement caused. Veterinary administrative and operational departments should earnestly implement prevention-oriented approach, the full implementation of disease control system, the major epidemic diseases prevention and control, combat and purification of work into the legal system. Aquaculture production enterprises should be carefully introduced egg, poultry chicks; strict disinfection, sanitation management, and strict compliance with, and seriously implement the "The People's Republic of China on Animal Epidemic Prevention" in the relevant supporting immunization, control and eradication of diseases of the specific provisions. View of the current confusion in the market of veterinary drugs and counterfeit veterinary drugs, vaccines into the market situation, we should intensify law enforcement to give severe punishment for offenders. Avoid the use of fake veterinary drugs and vaccines, caused by immunization failure, resulting in serious economic losses. China's accession to WTO, import and export of animals and their products become increasingly frequent, the disease will also increase opportunities for the introduction, therefore, customs, animal and plant quarantine agencies should strengthen technological development to raise professional level, take preventive measures, the refusal of animal diseases in the outside the country.
3. Increase the promotion of new technologies, improve the level of feeding and management to gradually improve the poultry industry and related industries an operational capacity, technical expertise, should be taken to carry out lectures, training workshops and sharing of experiences and other forms, so that birds Disease diagnosis and control techniques to promote their new achievements, so that they, especially the grass-roots knowledge of veterinary personnel gradually spread and increased. In addition, the level of feeding and management should be raised through government agencies and professional and technical personnel of the guide, so that the farmers do not over-intensive within a region to set up farms, and the implementation of the "all-in all out" rearing methods. The rational use of drugs, strict control of pharmaceutical products, residues and additives, residues, improve product quality, reduce morbidity, increase economic benefits.
4. Controlling environmental pollution and implement bio-security measures that environmental pollution is caused by the spread of epidemic diseases is one important factor. With the development of aquaculture, poultry farms feeding the growing environmental pollution, emphasizing the importance of environmental factors in the poultry disease prevention and treatment of even more practical significance. While some of China's large-scale, intensive aquaculture farms in terms of better, but there are environmental problems, due to inadequate investment in environmental governance, a number of long-standing disease, and new diseases from time to time; In contrast, the vast sectors of rural farming feeding conditions are poor producers lack knowledge of disease prevention, disinfection lax environmental pollution is getting worse. Therefore, we must adopt the "all-in all out" system, and chicken house a thorough cleaning to reduce the spread of diseases opportunity to strictly abide by the quarantine system and restrictions on people, animals and vehicles entering and leaving farms. Of morbidity and mortality of poultry, must be strictly dealt with to prevent disease spread. On the introduction of poultry to conduct rigorous health checks, do not be sick into the venue. In recent years, the international community's "bio-security" system theory, emphasizing environmental factors in the protection of animal health in an important role. Through the implementation of "biosecurity" technology, to improve the quality of poultry and their products, reduce costs and improve export competitiveness, access to better economic benefits. Therefore, guidance and help poultry companies do a variety of immunization, sanitation and disinfection, to minimize the land, water and air pollution of great significance.
5. The effective functioning of national or provincial animal disease diagnostic laboratory synthesis and improve disease diagnosis. Effective poultry disease prevention and control depends on accurate diagnosis of science, which depends on a variety of laboratory diagnostic techniques integrated. China's animal disease laboratory diagnosis needs to be improved, not only additional equipment, but rather focus on solving the supporting R & D and has an integrated diagnostic reagents to determine the ability of technology ranks. Ministry of Agriculture and the provincial authorities, should be targeted to support those who already have some basic laboratory equipment and work, mainly to maintain a certain amount of operating costs and part of the laboratory reagent costs.
In short, before joining the WTO, China's poultry disease prevention and control research on the one hand as soon as possible with international standards, and should focus on solving the unique problems of China's avian diseases, on the other hand, should the current stage of research on poultry in the world to track a gradual transition to research things on your own , taking the road with Chinese characteristics, research on poultry. For China's poultry disease prevention and control to a new level, to adapt to poultry industry, rapid and stable development of the relevant functional departments at all levels of support, supervision and coordination; a variety of relevant policies and regulations and establish and perfect the system; poultry effective control of the ecological environment, the main diseases of the purification and fight to "prevention first" comprehensive prevention health measures implemented; avian diseases related disciplines of science education and scientific research progress and development, and so are our poultry disease prevention and control countermeasures to be taken.
World Poultry Disease Research Progress and poultry disease control strategy in China Time :2009-09-07 Source: Benwang editing Author: admin
Animal Husbandry Co., Ltd. Henan China Region Manager,
China's poultry industry continued to grow steadily for 20 consecutive years, made remarkable achievements as the world's poultry power. According to the Ministry of Agriculture statistics, in 2000 China's meat output reached 62.7 million tons, per capita consumption of 52kg. According to UN Food and Agriculture (FAO) statistics, in 2000 China's output of eggs to 22.16234 million tons, accounting for 41.9% of world output, including eggs, 18.86 million tons, accounting for 85% of total output, per capita amounted to 17.7kg , total output and per capita volume ranking first in the world. Since reform and opening, eggs an average annual growth rate of 13.5%.
However, the poultry disease has been plaguing China's poultry industry, one of the key issues. At present there are about 80 kinds of China's poultry disease, which accounted for 75% of infectious diseases, resulting in enormous economic losses, has become a constraining bottleneck in the development of China's poultry industry. The survival rate of China's poultry is not high, with an average mortality rate of about 20% compared with developed countries, to more than one times the estimated average annual loss of poultry deaths in our country billions of dollars of production performance degradation caused by the disease, prevention and control expenses and other losses are more serious. Information shows that China's average per bird feeding vaccines and drug costs for the United States 10 times.
This shows that China's poultry disease prevention and treatment as compared with the world's developed countries, there are still gaps in today's accession to WTO, China's poultry disease prevention and control is only as quickly as possible with international standards, establish an effective operation in line with our actual control strategies and measures can we truly make our poultry industry in the world. This paper introduces the research progress of the world's avian diseases, and to talk about China's poultry disease prevention and control strategies for shallow understanding.
1, the World Poultry Disease Research Progress
(A) important viral diseases research
1. Avian Influenza (Avian influenza, AI) avian influenza virus (AIV) is a Orthomyxoviruses Division, with 8 segments minus-strand RNA, encoding 10 proteins, which includes: haemagglutinin (HA), neuraminidase (NA) , matrix protein (M) and nucleoprotein (NP) and so on. According to HA (9 species) and NA (15 species) of different proteins, AIV is divided into several serotypes. Although the frequency of bird flu than Newcastle high, but it will enable the infected flocks with high mortality rates, and even the whole group was lost to human health are also under greater threat, therefore, cause for concern.
AIV based on the strength of the chicken pathogenicity, avian influenza virus can be divided into two categories: low pathogenic avian influenza virus (LPAIV) and the highly pathogenic avian influenza virus (HPAIV). LPAIV the general performance of chickens infected with low mortality rates, accompanied by drop in egg production and minor respiratory symptoms, with mixed infection with other viruses or bacteria, the flocks may appear high mortality rate and most of the organ tissue lesions. On the contrary, HPAIV then produce high lethality, resulting in severe multi-organ infection in poultry in vivo, the mortality rate of up to 100%, and even endanger human health.
1.1 low pathogenic avian influenza in 2000, the United States in southern California, there are 10 commercial laying farms in the outbreak of low pathogenic avian influenza H6N2 type, 2001, there are still three flocks to detect AIV subtype H6 antibodies, but not isolated the virus. In early 2002, H6N2 in the central region of California commodities chicken, turkey and egg transmission.
In July 2002, in South Africa hens laying grower and meat kinds of egg drop occurs in chickens (about 50%), the mortality rate increased (about 20%), taking the organization of infected birds for virus isolation, by the agar immunodiffusion experiments, RT-PCR and serum typing proved to be H6N2 subtype LPAIV. 2002 in northern Italy, the outbreak of H7N3-type LPAI, seriously affected the export of poultry products.
In Asia the low pathogenic H9N2 more virulent, leading to high mortality rate occurred in chickens (10% ~ 80%) and reduced production performance. Isolated from diseased chickens to the H9N2 does not kill embryos in experiments, but also with the standard strain genome sequence comparison, homology is high. At the same time isolated from the diseased chickens also other respiratory pathogens: IBV, NDV, TRT, ORT, MG, MS, E. coli and so on, studies suggest that: two or more of the pathogenic infection is a collaborative LPAIV (H9N2) caused high mortality reasons, and no variations in virulence. However, the existing problems are: the use of H9N2 isolated from the production of oil-emulsion inactivated vaccine can effectively prevent a large number of chickens died, but did not prevent the drop in egg production in chickens, while China is not the case, the use of H9N2 oil production emulsion inactivated vaccine can effectively prevent the occurrence of H9N2 AI in chickens.
1.2 Highly pathogenic avian influenza in certain LPAIV (H6 and H7) in nature can be mutate into highly pathogenic strains, such as the United States (1983 ~ 1984), Mexico (1994 ~ 1995), Italy (1999 ~ 2002), Chile (2002). Some studies show that this change in virulence is due to avian influenza virus hemagglutinin HA gene and protection of sex-related cleavage site has changed (for some amino acid insertion) and caused by mutations of the genes and reported HPAIV environment in which genetically similar strains. 2002 Virginia 197 of the 4.7 million farms in the outbreak of H5N2 infection in poultry products.
Chile, in May 2001 took place LPAIV infection, isolated the H7N3 subtype virus isolated from a few weeks of the highly pathogenic strains. Through the low and high pathogenic H7N3 strain caused by the high of eight gene segments of the nucleotide sequence analysis, we found two more similar difference is that the highly pathogenic strain of the cleavage site of hemagglutinin gene of 30 nucleotide insertion, most likely two recombinant viruses generated.
1.3 Evolution of public health concerns from the animal point of view, the emergence of the avian flu virus than the human influenza virus early, so many scholars believe that a human influenza may be evolved from the avian flu, human influenza viruses and the emergence of pandemic strains of bird flu virus closely related. It was noted that a human influenza A 2 (H2N2) and A 3 (H3N2) subtype is likely to be human, avian flu virus through gene recombination came, it was also isolated from the flocks with people related to H1, H2, H3 subtypes of influenza viruses. Now widely recognized that cause human pandemic strain of a new subtype of influenza A virus, is directly or indirectly, by the people, the bird flu virus evolved by gene recombination. In August 1997, China's Hong Kong for the first time reported in 18 cases of H5N1 human infections of bird flu, of which 6 died, has aroused worldwide concern. After 1997, the world they have appeared in several avian influenza virus infection of human events. In February 2003, in our two cases of H5N1 occurred in Hong Kong's avian flu cases; 2003 2 to 7 months, 83 cases occurred in the Netherlands of avian influenza H7N7 human cases; in January 2004, the H5N1 in Vietnam suspicious persons cases of bird flu in the dead of the cases, five cases have been laboratory confirmed. In recent years, studies have shown that the avian influenza virus infection in human beings have three kinds of different subtypes. In 1996, in the United Kingdom from a woman suffering from conjunctivitis, the eyes of the duck in an H7N7 virus isolated. In 1997, in Hong Kong died from a child who isolated a virus, H5N1 subtype. In 1999, China's Hong Kong 2 1-year-old and 4-year-old girl in the isolated influenza rehabilitation of two separate strains of H9N2 subtype. Therefore, the experts say: highly pathogenic avian influenza virus, such as H5N1, H9N2, H7N7, etc. may result in the event of mutation of avian flu epidemic populations, suggesting the bird flu virus on humans have great potential threat.
1.4 Since the birds and wild waterfowl are the natural AIV storage host, then the eradication of the disease is difficult, even impossible. Must take steps to block poultry and wild waterfowl, direct or indirect contact, contact with prey (especially waterfowl) and people into the chicken coop before changing clothes and bathing. Vaccine and strict quarantine measures should be combined in order to control the commodity groups in chickens and turkeys, the occurrence of mild-type AIV. As for the virulent AIV infection, strict isolation and out of sick chickens to be effective measures. Many parts of the application of highly pathogenic avian influenza virus, inactivated vaccine has been paying off.
1.5 Prevention, control and fight OIE strategy for HPAI is classified as category A infectious disease, usually abroad, isolation, culling approach to risk areas, as the center to establish the immune quarantine area, slaughter of infected flocks, but this requires adequate financial compensation as a backing. For developing countries, at present, more and more people believe that vaccination should be included in HPAI control program, and isolation and quarantine, perfect combination of biosecurity and culling is a good way to control the disease. Vaccination is an important measure to eradicate this disease, due to the bird flu virus serotypes are many different subtypes of avian flu vaccine to protect a type-specific.
Focus on bio-safety is to reduce or avoid the key factor in chickens infected with AIV, such as strengthening farm (homes) and outside of the isolation and disinfection of vehicles and personnel between the strict disinfection to reduce the AIV by the tires, shoes, spread, decline of foreign personnel, attention to water and feed hygiene and so on.
2. NDV (Newcastle disease, ND) ND is a worldwide problem, is still against the majority of countries, especially developing countries, the poultry industry, the primary disease. According to statistics, in 2001 in 63 countries and territories reported that the disease occurs. From a global perspective, the NDV virulent than the highly pathogenic avian influenza reported to be much more. NDV is a paramyxovirus family, to have enveloped negative strand RNA virus, the virus genome mutations are sensitive, but because NDV genome is linear, so the speed variation than eight segments of avian influenza virus rapidly. Since NDV is only one serotype, therefore, different vaccine strains have some cross-protection.
Because the vaccine's widespread use of Newcastle disease in the world has been better control, but by low virulent Newcastle disease virus, egg-laying chickens caused by drop, mild respiratory symptoms and low mortality rates have occurred. Especially in recent years, highly virulent NDV in chickens caused by high mortality rates and a significant decline in egg production are still a number of countries reporting.
Due to the presence of avian influenza, Newcastle disease no longer has the diagnosis of clinical symptoms, diagnosis must be separated by pathogens. Studies suggest that in most parts of the outbreak of virulent Newcastle disease in chickens is due to poultry house environment, the existence of highly pathogenic NDV, is characterized by the F fusion protein on a particular site -113RXR/KR * F117-, not by low - Virulence conversion came. Newcastle disease virus variation remains a mystery, yet to be further confirmed.
Newcastle has been OIE classified as category A infectious disease of world trade have a greater impact, therefore, a good control measures is the study of hot spots. The use of live vaccine and inactivated vaccine against Newcastle disease on many occasions to strengthen the immune system can effectively prevent the occurrence of Newcastle disease, but this the one hand, an increase of vaccine costs, on the other hand are likely to flock will have a greater stress, so that their production performance. Vaccination can reduce the morbidity and mortality, relieve symptoms, reduce the virus in the body environment, the quantity, but the vaccine does not provide 100% protection, therefore, in order to better prevent the occurrence of Newcastle disease, but also should pay attention to bio - security.
3. Avian lung infection (Avian pneumoviruses infection) Avian Pneumovirus (APV) is a turkey rhinotracheitis (TRT) and chicken pathogenic lung infection in chickens after infection usually occurs swollen head syndrome (SHS). APV has occurred in Europe, Asia, South America and Central America, originally under the glycoprotein gene (G) the difference is only found in two serotype A and B, 1996 outbreak of the disease in the United States, and then matrix protein (M) and the fusion protein gene (F) difference found in a third serotype C, the recent French scholars in vivo isolated from duck to the fourth serotype D. APV infection in the United States, the first occurred in Colorado, Minnesota, after the near endemic, the place is a turkey breeding of high-density areas, C-type APV with human pneumonia virus A or B-type were similar.
Europe APV early research work focused on the development of the disease live vaccine and inactivated vaccines, in general, as long as the correct use of these vaccines, the effects were very good, and the two serotypes can be cross-protection. APV after the secondary infection of chickens infected with Mycoplasma gallisepticum and Escherichia coli will become very serious disease, and another, IBV virulent APV would interfere with the replication in the trachea, these two diseases the vaccines would interfere with each other, which indicates that vaccine Application of the importance of timing. Recent U.S. studies have shown that C-APV Newcastle disease virus on chicken will enhance virulence.
Recent studies have shown that wild birds in the spread of APV played a great role in APV and NDV and AIV may be the same as the host spectrum is broad, but it still needs further investigation.
4. Infectious bronchitis (Infectious bronchitis, IB) was a global distribution of infectious bronchitis. IBV's host range is narrow, it causes widespread with a high degree of infectious and local characteristics of the rapid spread within the scope of the. Some strains only in specific countries only. The persistence of IBV in chickens there are some features, but at present the significance of these features is unclear. IBV primarily caused by respiratory diseases, but other causes can lead to the spread of the disease, although the kidney-type strains can cause kidney lesions and death of chicks, but the conventional respiratory-type strain compared to the lesion is a focal proliferation of, and there is no so fast.
Essentially eliminate the current IB is not yet possible, but the existing vaccines can provide good control of the disease help. IBV S1 gene differences in the amino acid sequence led to the emergence of variant strains, these strains of antigenic variation with the existing vaccine strains different, but will occasionally pathogenic to strong and persistent, the need to develop new vaccines, such as the European The 793B strains, 4 / 91 and CR88 strains. Fortunately, not all variants have the need for new vaccines, laboratory and testing in the traditional cross-may be to clarify the relationship between IBV strains, from a practical point of view, and testing under the protection of sub-type ratio derived from serotype or the efficiency of genotyping vaccine more effective.
In recent years, the molecular structure of the IBV and have a deeper understanding of immune mechanisms, which will control the disease is very important. For example, recently successfully developed a full-length IBV infectious clone, this clone can be a more secure, would not return to strong specific vaccine, it can deal with variations in strains of IBV. Study found that the immune mechanism, IB's immune not just determined by S1 gene, IBV of the other components also play a role, this finding could explain why some vaccines can be a number of IB significantly different variant to provide protection.
On the other hand, IB recombinant vaccine research has been important progress. The use of different types of IBV strains of the S1 gene was prepared by genetic recombination between the recombinant virus, which represents the future of IB vaccine research focus and direction. U.S. scholars Beaudette as a receptor for the S1 gene of the S1 gene of M41 Preparation of Recombinant IBV, experimental results show that the immune effect of recombinant and M41 rather, better than Beaudette, but much lower than the toxicity of M41, is an extremely with the development of promising vaccines.
5. Infectious bursal disease (Infectious bursal disease, IBD) IBDV caused by immune suppression, the emergence of super-strain, antigen variation and genetic change has caused poultry disease experts from the world's attention. IBDV strain has become the brooding phase of super-serious harms to the disease.
At present, IBDV molecular diagnostics has entered a new phase, VP2 protein gene RT-PCR and RFLP, nucleotide sequence comparison analysis techniques are being perfected. In addition, breakthroughs in vaccine research, namely, super-drug for IBD vaccine IM (Irwin Moulthrop) has been attenuated by cell passaging obtained. Abroad, have been used as carrier pox virus and baculovirus expressed VP2 proteins, expression products of both can be used as diagnostic antigens, but also can be used as immunogens, that is, genetic engineering vaccine.
6. Infectious anemia (Chicken infectious anemia, CIA) CIAV is a round circular DNA viruses, no envelope. Broader epidemic, the main show latent infection, is generally not a separate disease, immune suppression is stronger, can lead to shrinkage of the thymus and other lymphoid organs. In Nigeria, an epidemiological survey of 180 sera, 80% of the serum samples were positive, indicating a high rate of infection. Survey showed that about 30% of the SPF chickens positive for the CIA, a greater threat to the SPF chickens. In our country the dangers of CIA is also relatively large.
The CIA progress in molecular diagnosis of pathogens present have been established to detect infected cells CIAV the PCR method, PCR test results and pathogen isolation the same result.
7. Marek's disease (Marek's disease, MD) in recent years, MDV virulence increased, and this is an indisputable fact. The 20th century, 60s, MD incidence of toxicity-based multi-medium; 70 years, due to turkey herpes virus vaccine (MD-3) popularity, the incidence gradually transformed into virulent strains (vMDV). In 1983, the U.S. price of seedlings emerged 2 (SB1 + HVT), the incidence of clinical strains evolve into super-toxic (vvMDV), routine vaccines ineffective. Liquid nitrogen stored MD-1 vaccine CVI988 (Rispens vaccine strain) is still the most effective vaccine.
MD vaccine genetically engineered vaccine is an important research direction. Glycoprotein B (gB) and other glycoprotein genes in fowl pox virus, HVT and MDV-induced weak virus vector has been expressed. These vector vaccines against Marek's disease induced protective immunity, but so far no one received a certificate to allow commercial use. Deletion mutant seedlings is to choose a strategy, but because there is not enough MDV genome, operational technology and has yet to be identified with the virus virulence genes that are directly related, so progress is slow. Meq gene deletion has been completed, but perhaps due to the strain of proliferation in the body are not well, so that the mutant not provide a high level of protection force. However, it is now mastered the creation of mutant strains of the new technology, which will facilitate the potential of new vaccines to study gene function.
8. J ALV (Avian leukosis subgroup J) in the past 10 years, ALV-J subgroup retroviruses has led to the worldwide broiler losses. Because the disease is vertical transmission and horizontal transmission, Europe, the United States, many of Yuanzhong Chang affected to different degrees of harm, caused widespread concern around the world, the disease has been put on the purification of an important agenda. Australia in connection with specific ELISA, SPF cell culture and RT-PCR and other laboratory means to purify the disease was divided into three stages of the disease eradicated. Professor Cui Zhizhong in China in the Chinese J subgroup ALV and reticulo-endothelial hyperplasia virus (REV) of mixed infection caused by immune suppression carried out in-depth study.
(B) food-borne bacterial diseases research
1. E. coli disease (Colibacillosis) E. coli in the environment of poor and other vulnerable secondary pathogen infection, In addition, E. coli infection, the body's respiratory mucosa and intestinal mucosa damage, easy secondary ND, IB, ILT and the MG and other diseases, so that flocks of elimination rate and mortality. E. coli is a normal intestinal bacteria, is divided into pathogenic and non-pathogenic nature of two kinds. American scholars in the incidence of E. coli isolated from chickens in the R plasmid on tsh, iucC and cvaC genes, and healthy chicken gut E. coli R plasmid without these genes. Of E. coli typing results showed that the major countries of the world are basically the same pathogenic E. coli, mainly O78, O2, and O1 and so on. However, Gao Song and so on from China's 18 provinces, municipalities and autonomous regions out of isolation and identification of avian Escherichia coli 595, a total of 440 identified isolates of serotype O, of which O18, O78, O2, O88, O11, O26, etc. 6 serotypes were the dominant serotypes.
Since E. coli is easy to produce on the use of antibiotic resistance; antibiotics drug residue on people's health have a greater hazard in which poultry products subject to trade restrictions; infected with E. coli, the chickens died Amoy rate increased, an increase in visceral waste , using bacteria to seedlings of the same serotype immunity only bacteria have better results, and thus to find effective preventive measures are all problems facing the poultry farm. Scholars at home and abroad dedicated to disease-causing genetic analysis of subunit vaccine (F11, FT, TT) research. In addition, since the poultry producing yellow-green body of toxins isolated from the O157: H7 E. coli has been changed in the past that the avian source of E. coli infection of human views. O157: H7 can lead to human beings, including asymptomatic infection, mild diarrhea, hemorrhagic colitis, hemolytic uremic syndrome and other clinical manifestations.
2. Salmonellosis (Salmonellosis) Avian Salmonella disease is one or more of the genus Salmonella Salmonella in poultry caused by acute or chronic infectious disease, is divided into pullorum disease, fowl typhoid and fowl paratyphoid. Of which can be caused by salmonella in poultry paratyphoid infection and the wide variety of animals, and therefore suffering from fowl paratyphoid poultry products are often caused human salmonella infections and food poisoning is one of the important reasons, often in Europe, America, Japan and other lead to serious social health problems, has also become difficult for China's exports of poultry meat and egg products one of the main. In addition, due to poultry production units for the control of poultry salmonellosis or purification and feeding a large number of drugs, often lead to severe drug-resistant strains, or a certain degree of drug residues also affect the international trade in poultry products. Recently, Salmonella enteritidis has been approved for use in inactivated vaccines. Association of British law requiring all poultry flocks must be vaccinated in this vaccine, In addition, an attenuated Salmonella Enteritidis vaccine immunization of drinking water has also been approved.
Relating to the classification of Salmonella have been improved, according to a new classification method, Salmonella is divided into two kinds, namely, S.enterica and S.bongori, more than 2,500 serotypes. Since the eighties from the last century, humans and animals, the prevalence of non-typhoid salmonella occurred in two major changes. First, the multi-drug resistant Salmonella typhimurium and its application in food animals, the emergence of groups in the dissemination of information; Second, as a major source of pathogens in eggs? The emergence and prevalence of Salmonella enteritidis.
3. Campylobacter jejuni disease (Campylobacteriosis) Campylobacter jejuni can cause many diseases occur in humans and animals, and is a food-borne pathogens, in a certain range of its food-borne bacterial infection caused by more than Salmonella, Campylobacter jejuni has been the safety of poultry products pose a serious threat. Bacteria not only cause human fever, acute enteritis, the reactive arthritis, Reiter's syndrome and Green? Barre syndrome, a disease characterized by autoimmune diseases can also cause hepatitis, turkey and blue crown diseases of broiler chicken and the chicken necrotizing hepatitis, chicks, calves, piglets, diarrhea and other diseases. In the United States each year by approximately 2.4 million cases of gastroenteritis caused by Campylobacter jejuni, accounting for 1% of the total population of a 2%. Contact or consumption of poultry products are considered the major route of transmission, according to surveys, 75% of the market for sale of live poultry and poultry meat contains 80% of Campylobacter. For more than 30 countries, surveys show that the mid-80 Campylobacter jejuni in chicken products have been widely distributed. Early scholars believe that the vertical transmission of bacteria can not occur, but recent studies have shown that there is a low level of vertical transmission of bacteria. According to another study confirmed that once the chicken cecal Campylobacter jejuni to settle these bacteria can be up to 8-week experimental period persists, and the chicken-derived strains after passage through chickens increased virulence. This shows that flocks of poultry are horizontal transmission of Campylobacter jejuni, long-term growth of contaminated poultry contaminated with the cause of the rising age.
PCR method using Campylobacter flaA gene fragments highly conserved sequence of SVR were amplified by fast detection of chicken feathers and egg shell or in the presence of Campylobacter in poultry meat.
Second, China's poultry disease control strategy for
(A) At present, the main features of China's poultry disease epidemic
1. More and more types of poultry disease, but most harmful infectious diseases, according to incomplete statistics, cause harm to the poultry industry has reached more than 80 kinds of disease, but with the largest number of infectious diseases, accounting for 75% of the total number of poultry disease above, it is estimated that China's annual poultry disease caused by various types of poultry, the mortality rate as high as 20% of the economic losses of billions of dollars.
2. An increased range of new cases emerging avian diseases in China mainly include: chicken infectious anemia, avian flu, different disease-type avian infectious bronchitis, infectious virus gonads gastritis, Muscovy duck parvovirus disease, chicken viral arthritis, production Egg drop syndrome, avian reticuloendothelial hyperplasia, J subgroup leukemia, ascites syndrome, and so on.
3. Pathogen mutation, clinical symptoms atypical of recent years, the incidence and prevalence in the poultry disease process, as some avian diseases pathogens occurred mutation, resulting in atypical of clinical symptoms. As the atypical is the most obvious example of Newcastle disease, infectious bursal disease virus and Marek's disease virus strains have emerged superior. Antigenic structure of mutation and serum-type variable, so that some vaccines prevention and control more difficult. Avian infectious bronchitis, previously endemic in our country mainly respiratory type, 90 years addicted to kidney-type emerged in recent years has emerged proventriculus type, making vaccine research has become increasingly difficult. If you are using the vaccine and epidemic strains of serotype inconsistent, often leads to vaccine failure. Another example is Marek's disease, in the 20th century, 70's, the wild strains are virulent mainly to the 80's, some countries of the super-drug, and 90 years in the United States and Europe have emerged super strains Each time the enhanced virulence of pandemic strains have led to failure of the existing vaccine. Foreseeable future, both in prevalence of poultry diseases, or disease-causing mechanism of the city on the increasing complexity of the requirements of our veterinary workers are increasingly high.
4. Drug-resistant bacteria become more serious and long-term due to the overuse of antibiotics and feed additives, adding low doses of antibiotics, leading to bacterial resistance is increasingly common, more serious, resulting in control of bacterial diseases become a major challenge. Zhi-Ming Pan, Jiao Xin and other pairs of 1962 to 1999 in some regions of Salmonella pullorum trends in drug resistance study found that bacterial resistance patterns over time and gradually widened until the late 90s, bacteria may be simultaneously 10 two kinds of antibiotic resistance.
5. Subclinical immunosuppressive diseases has become increasingly common multi-infection of a common immunosuppressive virus: Marek's disease virus, infectious bursal disease virus, Reticuloendotheliosis virus, chicken infectious anemia virus, reovirus Virus (infectious arthritis virus), chicken leukemia virus. Immunosuppressive viral infection hazards mainly as follows: to make viral and bacterial infections are not typical symptoms of disease; for specific immune response to vaccines, decline or lack of response (such as the HI low NDV), and secondary bacterial infection increased significantly. Because of immune suppression is difficult to diagnose viral infection has been neglected, together with a number of immunosuppressive virus infection in non-vaccine-preventable, and more emphasis on its hazards.
(B) the status quo of China's poultry disease prevention and control
1. Poultry disease prevention and control research in China made important progress in
1.1 Etiology of more in-depth in the use of conventional serological method of the basic characteristics of pathogens at the same time, in the pathogen's molecular biology have also been extensively studied. Such as the viral nucleic acid genome sequence or primary immunization of the original gene sequence determination, so that people can more clearly recognize pathogen occurred molecular basis of genetic variation, in order to predict the evolution of the disease has laid a foundation; encoding structural protein amino acid sequence of derivation, as the major immunogenic proteins to identify and carry out specific diagnostic reagents or genetically engineered vaccine provides a means and basis for such. So far, affecting the healthy development of China's poultry industry, the major diseases such as avian influenza, Newcastle disease, Mark Li's disease, infectious bursal disease, infectious bronchitis, etc. The main pathogenic gene sequence or its genome sequence has been determined , but also from the molecular level on some pathogens of wild strains and vaccine strains Differences between the structure of nucleic acids, which are evolution and development of disease revealed a certain degree of molecular genetic variation of the law. But on the whole, the pathogenicity of the pathogenic mechanism and the immune mechanism of the breadth and depth to be the development of molecular function of important pathogens are still not thorough enough, to track work the high side, originality, or too few features of the results.
1.2 Disease diagnosis technology developed rapidly serology, immunology, combined with clinical symptoms of pathological diagnostics techniques and methods to the entire poultry disease prevention and control is almost in-depth research, and some serological methods has developed into a preliminary diagnostic reagents (Box ), such as the University of Newcastle disease Yangzhou Virulent rapid ELISA diagnostic kit, Salmonella ELISA-PCR co-detection kit, as well as H5, H9 subtype of avian influenza virus rapid detection of multiple RT-PCR kits, etc.; Henan Academy of Agricultural Sciences IBD colloidal gold Diagnostic Kit; China Agricultural University, College of Veterinary Medicine of the lymphatic leukemia ELISA diagnostic reagents, Beijing Academy of Agriculture and Forestry Animal Husbandry and Veterinary Research Institute of Infectious rhinitis ELISA diagnostic reagents, etc., these preliminary diagnostic reagents (Kit) have greatly improved the speed of diagnosis, and convenient operation, high accuracy, for the commercialization of China's poultry disease diagnostic reagents opened the way for the development. But the poultry disease diagnostic studies, the emphasis on technology, the phenomenon of light products, universal, independent research and development of a real clinical need for new diagnostic reagents (box) not more than, not to mention the formation of brand products.
1.3 to accelerate the pace of new vaccines to protect the traditional vaccine production and the health of the poultry industry has played a huge role in the development of the current vaccine used in virtually all the major infectious diseases of poultry. However, with modern immunology, molecular biology techniques and the rapid development of the immune poultry disease prevention needs of practice, and new vaccines continue to emerge. Such as the recombinant virus vaccine, recombinant bacterial vaccine, gene deleted vaccines, multi-epitope vaccines could feed vaccines and DNA vaccines, these vaccines in laboratory studies and have a certain immunity effect, but how widely used in clinical practice is still a lot of work to be done, but it gives people in the vaccine research and development provides new ideas and thinking. It is noteworthy that the new vaccine research in empirical research model still accounts for a considerable proportion of the vaccine rational design of a new model has produced prototype, but the accumulation of a serious shortage of theories and technologies.
1.4 Disease mechanism of deepening the pathogenesis of the disease in poultry has been the focus of research on poultry, conventional methods from the sharp eyes and the cellular level, tissues and organs under the microscope to study and practice of Microbiology & Immunology to study the cellular level, with the molecular biology and the universal application of electron microscopy, so that poultry disease researchers from the molecular level on the mechanism of disease research. Research in this area, should the pathogen? Host interactions in the law will accomplish a great deal.
2. Poultry disease prevention and control of China's major problems
2.1 Non-standardized model of poultry, poultry production units in various forms of ownership, size Dazhong Xiao San coexist, facilities and technological level of high, low, simple as in, bio-security quarantine system is not perfect, vaccines, veterinary medicine, feed, misuse of a serious, leading to the disease is difficult control, the product can not meet the "high-quality, safe, pollution-free" in the pursuit of food consumption.
2.2 Import many diseases, such as EDS-76, J-AL, CIA, HPAI, RE and so on.
2.3 The flow of poultry and their products are not standardized for all the right to slaughter the Chinese goose, poultry and their products are not only the charges and quarantine, no quarantine, no charge, unauthorized sale, purchase, transport dead poultry and their products is widespread .
2.4 The legal system is not perfect in China and animal diseases and food safety-related laws, "Food Sanitation Law" (1983), "Infectious Diseases Prevention Law" (1989), "Import and Export Quarantine Law" (1989), "import and export of animals and plants Quarantine Law "(1992)," Animal Epidemic Prevention "(1998)," Veterinary Regulations "(1987)," feed and feed additives regulations "(1999), etc. Most of these laws and regulations based on legislative drafting department, with to a lot of drawbacks, and some are still many gaps in the law, some conflicting, some with international law does not converge, and some bad, and so operability.
2.5 Veterinary institutional problems in the present, the European Union on China's veterinary health management system to hold strong objection. If China's farming and export processing enterprises in the different departments in the implementation of veterinary health, veterinary supervision, including both the State animal husbandry and veterinary department of veterinary presence, there are entry-exit inspection and quarantine agencies as well as the enterprise's own veterinarian veterinarians. The EU clearly stated that only the national veterinary authorities to send veterinarians to the production and processing enterprises of poultry and their products to implement the legitimate veterinary health supervision, no other veterinary supervision of the legal qualifications. Because the entry-exit inspection and quarantine system of veterinary confined to port and export products, and can not cover all the livestock and poultry products, while the EU requires a company's products must all meet the veterinary hygiene standards in order to effectively guarantee the quality of the product exports to the EU in order to export to the EU , the same company's products can not be because of domestic, export of difference and the implementation of the different veterinary health regulatory procedures. In addition, the enterprise itself as an enterprise of the veterinary staff is serving the interests of the enterprise, its production process, inspection and quarantine work, can not represent the country's veterinary health regulatory procedures. The agricultural system within the city, county veterinary system is the set of disease prevention, quarantine, services, management, and supervision in one.
2.6 vaccines, veterinary drugs, feed production and sale of fake and shoddy products too. Too many small-scale duplication and form can not be together, brand-name products too little.
(3) China's poultry disease control strategies
Due to the above problem exists, poultry disease has constrained the development of our national poultry industry an important factor. With the intensification of China's poultry improvement in the level, if not do a good job poultry disease prevention and control work, poultry disease caused by direct or indirect losses will be even more serious. According to expert estimates, the size of flocks for each doubling of the incidence of the disease on the rise six-fold. Therefore, the rapid increase in China's poultry disease prevention and treatment as soon as possible with international standards has become imperative.
1. Strengthen the scientific research
1.1 to strengthen basic research using molecular biology tools, combined with conventional technology, an important molecular etiology of infectious diseases of poultry research, carried out analysis of the genetic structure of pathogenic microorganisms, the specific components of pathogenic microorganisms and toxins, surface antigens, such as genetic mapping, cloning and expression, analysis of their pathogenicity, Genetic variation, resistance mechanism, and the antigenicity of the active ingredient and animal pathogens in the laws of the interaction between body, which for a number of major infectious diseases (including the important zoonoses) in occurrence and development of process and control methods for the analysis of micro-biology studies. To identify the origin of infectious diseases and drug therapy target. Anti-sense nucleic acid technology, nucleic acid technology and bio-reactor technology research, to explore gene therapy, poultry and genetically modified disease-resistant breeding and disease prevention, application of protein production approach. Active immunization of poultry biology research, while improving on drug pharmacology and toxicology research on poultry physiology research, the study of parasites, to enhance the poisoning of poultry diseases, parasitic diseases, nutrition, metabolic diseases and other common diseases the control level. At present, the veterinary scientific research should be more concerned and resolve animal people Zoonosis of public health and food safety basic research.
1.2 to strengthen veterinary drugs and veterinary biological products, examine the use of chemical and biological engineering, new technologies, research and development of oligonucleotides, carbohydrates, peptides, proteins and other chemical synthetic antibacterial drugs and semi-synthetic antibiotics and a new hybrid antibiotics, to find good curative effect and low toxicity, pollution-free, inexpensive, easy to use anti-bacterial drugs. While strengthening the study of traditional Chinese herbal medicine to develop a quick, long-lasting, non-residue of traditional Chinese medicine preparation. Research and development of new antibiotics alternatives. Strengthen the veterinary biological products research. In the traditional vaccine research, the system should focus on vaccine strain selection and optimization of seedlings, tissue culture techniques and the protection of the vaccine agent, diluent, adjuvant, immune enhancer studies, thereby enhancing the immune effect of the vaccine, to reduce production costs and reduce the incidence of vaccine failure. In the new vaccine research, to speed up genetic engineering subunit vaccines, gene deletion or mutation of vaccines, live vector vaccines, DNA vaccines and genetically modified may be fed vaccines. Focus on non-pathogenic viruses and bacteria as a novel expression vector and transformation, and of sub-types are more pathogenic for multivalent subunit vaccine and multi-gene engineering vaccine of the research. In addition, according to China's existing research base, the use of immunology, serology and molecular biology approach to a variety of avian diseases fast, simple, accurate, sensitive and inexpensive diagnostic kit for the commercialization of research and development work.
1.3 to strengthen basic research in poultry disease epidemiology and disease monitoring system for the construction of epidemiological data collection is a long-term, daily work, disease monitoring system for the establishment and effective operation of the basic guarantee of this work. According to China's animal disease prevention and control of the actual needs of basic research should be strengthened epidemiological and form networks and systems.
2. Strengthen law enforcement, prevention, healthy avian diseases disease prevention system to prevent animal diseases from entering the prevalence of poultry diseases, in large part because of lax enforcement caused. Veterinary administrative and operational departments should earnestly implement prevention-oriented approach, the full implementation of disease control system, the major epidemic diseases prevention and control, combat and purification of work into the legal system. Aquaculture production enterprises should be carefully introduced egg, poultry chicks; strict disinfection, sanitation management, and strict compliance with, and seriously implement the "The People's Republic of China on Animal Epidemic Prevention" in the relevant supporting immunization, control and eradication of diseases of the specific provisions. View of the current confusion in the market of veterinary drugs and counterfeit veterinary drugs, vaccines into the market situation, we should intensify law enforcement to give severe punishment for offenders. Avoid the use of fake veterinary drugs and vaccines, caused by immunization failure, resulting in serious economic losses. China's accession to WTO, import and export of animals and their products become increasingly frequent, the disease will also increase opportunities for the introduction, therefore, customs, animal and plant quarantine agencies should strengthen technological development to raise professional level, take preventive measures, the refusal of animal diseases in the outside the country.
3. Increase the promotion of new technologies, improve the level of feeding and management to gradually improve the poultry industry and related industries an operational capacity, technical expertise, should be taken to carry out lectures, training workshops and sharing of experiences and other forms, so that birds Disease diagnosis and control techniques to promote their new achievements, so that they, especially the grass-roots knowledge of veterinary personnel gradually spread and increased. In addition, the level of feeding and management should be raised through government agencies and professional and technical personnel of the guide, so that the farmers do not over-intensive within a region to set up farms, and the implementation of the "all-in all out" rearing methods. The rational use of drugs, strict control of pharmaceutical products, residues and additives, residues, improve product quality, reduce morbidity, increase economic benefits.
4. Controlling environmental pollution and implement bio-security measures that environmental pollution is caused by the spread of epidemic diseases is one important factor. With the development of aquaculture, poultry farms feeding the growing environmental pollution, emphasizing the importance of environmental factors in the poultry disease prevention and treatment of even more practical significance. While some of China's large-scale, intensive aquaculture farms in terms of better, but there are environmental problems, due to inadequate investment in environmental governance, a number of long-standing disease, and new diseases from time to time; In contrast, the vast sectors of rural farming feeding conditions are poor producers lack knowledge of disease prevention, disinfection lax environmental pollution is getting worse. Therefore, we must adopt the "all-in all out" system, and chicken house a thorough cleaning to reduce the spread of diseases opportunity to strictly abide by the quarantine system and restrictions on people, animals and vehicles entering and leaving farms. Of morbidity and mortality of poultry, must be strictly dealt with to prevent disease spread. On the introduction of poultry to conduct rigorous health checks, do not be sick into the venue. In recent years, the international community's "bio-security" system theory, emphasizing environmental factors in the protection of animal health in an important role. Through the implementation of "biosecurity" technology, to improve the quality of poultry and their products, reduce costs and improve export competitiveness, access to better economic benefits. Therefore, guidance and help poultry companies do a variety of immunization, sanitation and disinfection, to minimize the land, water and air pollution of great significance.
5. The effective functioning of national or provincial animal disease diagnostic laboratory synthesis and improve disease diagnosis. Effective poultry disease prevention and control depends on accurate diagnosis of science, which depends on a variety of laboratory diagnostic techniques integrated. China's animal disease laboratory diagnosis needs to be improved, not only additional equipment, but rather focus on solving the supporting R & D and has an integrated diagnostic reagents to determine the ability of technology ranks. Ministry of Agriculture and the provincial authorities, should be targeted to support those who already have some basic laboratory equipment and work, mainly to maintain a certain amount of operating costs and part of the laboratory reagent costs.
In short, before joining the WTO, China's poultry disease prevention and control research on the one hand as soon as possible with international standards, and should focus on solving the unique problems of China's avian diseases, on the other hand, should the current stage of research on poultry in the world to track a gradual transition to research things on your own , taking the road with Chinese characteristics, research on poultry. For China's poultry disease prevention and control to a new level, to adapt to poultry industry, rapid and stable development of the relevant functional departments at all levels of support, supervision and coordination; a variety of relevant policies and regulations and establish and perfect the system; poultry effective control of the ecological environment, the main diseases of the purification and fight to "prevention first" comprehensive prevention health measures implemented; avian diseases related disciplines of science education and scientific research progress and development, and so are our poultry disease prevention and control countermeasures to be taken.
