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Trinidad and Tobago: Preparing for Bird Flu

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  • Trinidad and Tobago: Preparing for Bird Flu

    Preparing for Bird Flu

    http://sta.uwi.edu/uwiToday/2006/April/birdflu.asp

    UWI Today Home

    by Dr Marlon Knights, Lecturer, Department of Food Production and President, APSATT

    This was the major focus of a symposium hosted by the Department of Food Production (DFP) and the Association of Professional Agricultural Scientist of Trinidad and Tobago (APASTT). The symposium brought together key stakeholders in the poultry industry including company representatives, contract farmers, consumers, scientist and government officials to share information, highlight the strengths, weaknesses, opportunities and threats existing in the industry and to discuss the requirements necessary for the protection and continued growth on arguably one of the largest components of the agricultural sector. A summary of some key findings is presented.
    Understanding Bird Flu and Potential Impact of the Disease

    The poultry industry employs over 10,000 persons and contributes 62 percent of agricultural GDP and is estimated to be worth more than US$150 million. Poultry meat is widely consumed in Trinidad and Tobago and is a reliable, cheap, high quality source of protein for our population. Additionally, the consumption of locally produced poultry meat saves the country in excess of US$100 million in foreign exchange. However, all is not well in the poultry industry. Contract farmers are concerned about the sustainability of the industry, fairness of contracts, and insurance and compensation. Poultry companies are concerned about the impact of trade policies, fluctuating prices of inputs and inadequate governmental and institutional support, and consumers are worried about the price and safety of poultry products. The latter was clearly demonstrated by the changes in consumption following reported outbreaks of Aspergillosis. The survival and continued development of the industry necessitate that the concerns of consumers must be addressed in order to maintain confidence in the local poultry industry. With consumers demanding a healthier, safer and more affordable product the introduction of diseases such as Bird Flu into Trinidad could, therefore, have disastrous consequences to the industry and the population that depend on poultry to meet their protein requirements. Understanding and developing strategies to prevent the introduction of, or to quickly identify and eliminate, diseases is an important strategy to protect the industry.
    So what is Bird Flu?

    Bird Flu or Avian influenza is an infection caused by avian (bird) influenza (flu) viruses. There are three types of influenza viruses, A, B and C. The A type virus affects poultry, humans and other mammals. There are also many different subtypes of type A influenza viruses. These subtypes differ because of changes in certain proteins on the surface of the influenza A virus (hemagglutinin [HA or H] and neuraminidase [NA or N] proteins). Many different combinations of HA and NA proteins are possible resulting in different types of viruses. Each combination represents a different subtype. All known subtypes of influenza A viruses can be found in birds. These influenza viruses occur naturally among birds but can infect multiple species including humans (H1N1, H1N2, and H3N2). Avian influenza viruses can also be classified as low pathogenic (LPAI) viruses which cause mild symptoms in birds and high pathogenic (HPAI) viruses which spread more rapidly through flocks of poultry and can cause disease that has a mortality rate that can reach 90-100 percent, often within 1-2 days. Our present concern is with the highly contagious and deadly Avian Influenza A (H5N1).


    H5N1 virus


    Avian Influenza A (H5N1) is carried in the intestines of free-flying aquatic birds, wild birds, domestic and pet birds. Some, but not all, wild birds get sick and die from this virus while others may serve as a reservoir for the disease. Healthy birds contract the disease through direct or indirect contact with infected wild migratory birds, or the faeces, saliva or nasal discharge of infected birds. It is estimated that a gram of faeces contains enough virus to infect 1 million birds and the virus can survive in manure for up to three (3) months. While the domestic chicken is highly susceptible to the H5N1 virus, ducks may contract the disease and show few, if any, symptoms and in so doing serve as a reservoir for the disease organism. In infected chickens the disease is characterized by sudden death, drop in egg production, facial edema, cyanotic combs and wattles.
    Can humans contract the disease?

    Avian Influenza (H5N1) is a zoonotic disease, and is therefore capable of causing disease in humans. According to the World Health Organization (WHO), since 2003 a total of 186 persons have contracted the disease. More than 60 percent of the cases (112) occurred over the last year, with most cases occurring in previously healthy children and young adults. In the current outbreaks of AI H5N1 in Asia and Europe the case fatality rate is approximately 56 percent. This means that more than half of the persons who contracted the H5N1 virus died from the disease. However, this figure must be carefully interpreted as it is likely that the only cases being reported are those in the most severely ill people. The symptoms of avian influenza in humans have ranged from typical influenza-like symptoms (e.g., fever of more than 38ºC, cough, sore throat, and muscle aches) to eye infections (conjunctivitis), pneumonia, acute respiratory distress and viral pneumonia.



    The H5N1 virus does not currently possess the ability for effective person to person transfer and so human infections has not continued beyond one person. Therefore, most cases of human AI H5N1 infection have resulted from direct contact with infected poultry or surfaces contaminated with the droppings or other secretions of contaminated birds. Poultry farmers and pluck-shop operators are therefore most at risk. Cooking infected poultry meat (above 70ºC) effectively kills the virus, thus, consumption of cooked poultry product does not represent a mechanism for contracting the disease. All influenza viruses have the ability to change (undergo genetic mutations). Scientists are therefore concerned that H5N1 virus might eventually achieve the ability for effective and sustained spread from human to human. The ability for effective human to human transfers together with the fact that currently there is little or no immune protection against them in the human population can result in an H5N1 influenza pandemic. The situation will be even grimmer if the virus also maintains its seemingly high case fatality rate.


    How can the disease be controlled?

    There is no treatment for the disease in poultry so our best approach to dealing with this disease is to prevent its introduction. The disease can be introduced into Trinidad and Tobago through migratory birds. This is perhaps the most difficult to eliminate. However, introduction might also occur through legal and illegal importation of infected birds or avian products, importation of contaminated vehicles and/or equipment, and through tourist and commercial activities. Heightened awareness and surveillance at our ports of entry would be necessary to reduce the chances of introduction by these methods. If the disease organism gains entry in to the country, then steps should be taken to quickly and positively identify and contain the organism within a narrow range of time, and to eradicate the organism before it spreads. These steps might necessitate the establishment of quarantine zones and the humane slaughter and disposal of all birds within that zone. A commercial vaccine has been developed for preventative use in poultry; however there is disagreement on whether vaccination should be used as part of a control plan in commercial poultry.

    Treatment of infected humans is possible but complicated by the limited effectiveness of approved influenza antiviral drugs. The H5N1 virus is resistant to two (amantadine and rimantadine) of the four antiviral medications commonly used for influenza. However, two other antiviral medications, oseltamavir (TAMIFLU™) and zanamavir (RELENZA™), have been recommended for the prevention and treatment of type A (H5N1) influenza in humans. Furthermore, the WHO has recommended that countries stockpile enough of these drugs to treat 25 percent of its population. The availability of these drugs has been a major limitation to countries meeting these goals. Currently, there is no commercially available vaccine to protect humans against the H5N1 virus. However, trials in the United States are currently being conducted to evaluate the effectiveness of a vaccine developed by Sanofi Pasteur. Recently the Hungarian company Omnivest also reported that they were successful in developing a vaccine against H5N1.
    What is being done to prepare for Bird Flu?

    Locally some efforts are being made by the various agencies and companies to prepare for Bird Flu. The Ministry of Agriculture has reportedly acquired the capacity to test for the disease, has stepped up their surveillance, has held some targeted group discussions on the disease and has formulated response strategies to potential outbreaks. The Ministry of Health has attempted to acquire the recommended therapeutic drugs, while the poultry companies have been advising their contractors on general biosecurity practices, including Bird Flu specific management practices such as “bird-proofing” their poultry houses, and removal of potential reservoirs of the H5N1, including domestic ducks. While these efforts are noble, by themselves they might not be effective in either preventing the introduction of the disease, or minimizing the severity of the impact once introduced. Furthermore, they by and large exclude the “small-backyard” poultry producer group who are more numerous in number and probably more vulnerable than most citizens.
    So what needs to be done?

    There are both general and specific issues that need to be addressed if the poultry industry and the country, by extension, are to minimize the potential effects of Bird Flu. Some of these issues and strategies were highlighted at the DFP/APASTT symposium and is also reported in the paper “A global strategy for the progressive control of HPAI” produced by the Food and Agricultural Organisation (FAO) of the United Nations and the Office International des Epizooties (OIE), the World Organisation of Animal Health. They include the development of a clear policy. Policy makers need to become fully aware of the potential impact of the disease on persons directly involved in the poultry industry, their dependents and, as a consequence, the wider society. They must also become familiar with the potential effect of the disease if it develops into a human pandemic. This awareness should drive the development of a policy that incorporates all stakeholders and should be targeted at the following goals:

    1. Prevention of the introduction of the disease. There should be adequate screening of travellers and imported products, including used cars that might originate from regions in which the disease has been detected, as well as appropriate testing of bird and bird products and the eradication of the illegal bird trade. As part of this process, our customs and quarantine services might need to be upgraded.


    2. Strengthening of the veterinary services and university laboratories to allow for greater surveillance and rapid testing. At present, our veterinary services lack the capacity to conduct rapid Polymerase Chain Reaction (PCR) based test. Rapid testing is necessary for rapid containment. Therefore, laboratories should be upgraded and necessary staff should be employed and trained.


    3. Increase in national surveillance. This should be done not only at contract poultry producer farms but also efforts should be focused on engaging hunters, foresters and game wardens who more frequently come in contact with wild birds.


    4. Facilitating early reporting and response to suspected cases. This can be encouraged by providing incentives to persons who report suspected cases that test positive for the virus.


    5. Development and implementation of effective control programmes. Various scenarios can be developed, appropriate responses can be planned and field simulations should be conducted to ensure the readiness of our various agencies. This should also include strategies for the humane culling and safe disposal of carcasses.


    6. Assessment of the socio-economic impact of the disease and possible control measures on poultry producers including “back-yard” farmers. Funds should be identified for compensating producers in the event that culling becomes necessary as part of the control program, keeping in mind a large number of small producers might be affected.


    7. Development of strategies for preservation of indigenous avian genetic resources. Since we do not know how susceptible birds, such as the Pawi, might be, a good policy would articulate steps to prevent the loss of our fragile genetic resources.


    8. Education of the public about the disease and keeping them informed about the level of preparedness. An educated, informed public is less likely to panic, and would be more willing to cooperate with the authorities in attempts to prevent the introduction of the disease, during surveillance visits, and during testing and culling, if that becomes necessary. An educational package should also be developed specifically for persons directly involved in the poultry industry, outlining bio-security measures and steps that might be taken to minimize risks of infecting themselves.


    9. Planning for a pandemic. We do not have a pandemic situation but we might. The potential cost in terms of lives and productive capacity necessitates that plans be made to deal with a Bird Flu pandemic, even at this early stage. Such a plan would include stockpiling of the necessary drugs, identifying hospital bed spaces that can be used as quarantine areas, updating health care professionals and assessing the socio-economic impact.
    Last edited by Sally Furniss; March 25, 2007, 05:05 AM. Reason: formatting
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