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[In-depth popular science] Hemorrhagic fever broke out? Experts answer for you
Source: China Digital Science and Technology Museum
2022-01-14 17:39:00
Since the beginning of winter, the new crown pneumonia epidemic in Xi'an has worried people all over the country. However, recently, many hospitals in Xi'an have received many patients with hemorrhagic fever. Immediately afterwards, news such as "eating strawberries causes hemorrhagic fever" and "Xi'an hemorrhagic fever" spread rapidly. An unfamiliar word, hemorrhagic fever, keeps appearing on various social media platforms, which has also caused a lot of concerns.
1. The "unfamiliar" hemorrhagic fever is actually not unfamiliar
When it comes to hemorrhagic fever, many people will feel unfamiliar, and there seems to be no similar cases around. In fact, hemorrhagic fever is not uncommon.
The incidence of hemorrhagic fever has a global distribution. Epidemiological surveys in recent years have shown that 32 countries in four continents including Asia, Europe, Africa, and America have experienced hemorrhagic fever patients or hemorrhagic fever epidemics. Generally speaking, hemorrhagic fever is mainly prevalent in China and South Korea in Asia, followed by countries such as Russia and Finland.
Among the countries in the world, China is a severe epidemic area of hemorrhagic fever. At present, the cumulative number of hemorrhagic fever cases reported in China has reached 1,650,000, accounting for more than 90% of the cases reported worldwide. In China, there are obvious geographical differences in the incidence of hemorrhagic fever. Although hemorrhagic fever can occur in various places, the incidence in the south is lower than that in the north, and the epidemic is most serious in the northeast and north China. Among them, Heilongjiang Province, Jilin Province, Liaoning Province, Shandong Province, Hebei Province and Shaanxi Province are the hardest hit areas for hemorrhagic fever, and Shaanxi Province, especially Guanzhong area, is the high incidence area of the disease.
Second, what is hemorrhagic fever?
Hemorrhagic fever is hemorrhagic fever with renal syndrome, also known as epidemic hemorrhagic fever, is a group of natural foci of infectious diseases caused by Hantavirus infection with rodents as the main source of infection. It is an acute viral infectious disease, which belongs to the Class B infectious disease of legal infectious diseases in my country.
The study found that: worldwide, the viruses that can cause hemorrhagic fever with renal syndrome include Hantavirus, Seoul virus and Pumara virus of the genus Hantavirus. In terms of viral toxicity, the toxicity of Hantavirus is significantly stronger than that of Seoul virus, and the virus that causes hemorrhagic fever with renal syndrome in my country is mainly Hantavirus.
Hemorrhagic fever with renal syndrome has become a worldwide public health problem
Hantavirus has a general susceptibility in the population, and people of different genders, ages and ethnicities may be infected with this virus. However, only a small number of people become ill after infection with hantavirus, and most people are in a latent state of infection that can last for several weeks.
Although the number of people infected with hantavirus is a minority, the hemorrhagic fever caused by infection often seriously threatens the life safety of patients. Hemorrhagic fever with renal syndrome has the characteristics of rapid onset, rapid spread, wide epidemic range, great harm and strong suddenness. Severely ill patients often have critical symptoms such as bleeding, acute renal failure, and shock, and the resulting mortality rate can exceed 5%. Therefore, it has become a worldwide public health problem of common concern.
The seasonal distribution is obvious
Epidemiological surveys in my country have found that the endemic areas of hemorrhagic fever with renal syndrome can be divided into three types: chiropractor type, house mouse type and mixed type. In the endemic areas of hemorrhagic fever with murine-type renal syndrome, the main source of infection was A. chinensis; in the endemic areas of hemorrhagic fever with murine-type renal syndrome, R. musculus was the main source of infection; House mice carry hantavirus. Although hemorrhagic fever with renal syndrome can occur throughout the year, there is a distinct seasonal distribution:
● Haemorrhagic fever with rat type renal syndrome: also known as type I or wild rat type, the peak season is autumn and winter, and it occurs frequently from October to January of the following year. Among them, November-December is the peak incidence, and some areas will have a small peak in June-July.
Haemorrhagic fever with murine renal syndrome: also known as type II or murine type, spring and early summer are the peak seasons of incidence, March-June is the frequent month, and April-May is the peak incidence;
● Haemorrhagic fever with mixed renal syndrome: the disease occurs throughout the year, and there will be double peaks in winter and spring. Generally, the winter peak is higher than the spring peak.
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At present, there are mainly three types of epidemic areas in my country: type I, type II and mixed type. Shaanxi Province belongs to the mixed epidemic area of hemorrhagic fever with renal syndrome mainly caused by type I virus infection. The incidence of hemorrhagic fever with renal syndrome often fluctuates periodically. For example, in the epidemic area where the main source of infection is agaric rats, there will generally be a major epidemic every few years. This also explains why hemorrhagic fever cases have been concentrated in Xi'an some time ago.
The common causes of hemorrhagic fever
Hemorrhagic fever with renal syndrome is a severe systemic inflammatory disease caused by various types of Hantavirus infection. After entering the human body, hantavirus can cause viremia, leading to pathophysiological changes such as vascular endothelial damage, increased vascular permeability and hemorrhage.
After entering the human body, hantavirus can directly destroy the function and structure of cells, and also induce innate and adaptive immune responses, stimulate the body to release a variety of cytokines and inflammatory factors, and cause edema, diarrhea, hypotension, and shock in patients. Clinical manifestations of multiple organ damage.
What are the symptoms of hemorrhagic fever?
The incubation period of hemorrhagic fever with renal syndrome is about 4-46 days, usually 7-14 days. Fever, hemorrhage and kidney damage are the three typical clinical manifestations of hemorrhagic fever with renal syndrome. The course of the disease includes five stages: fever stage, hypotension shock stage, oliguria stage, polyuria stage and recovery stage. In addition, in some patients, the progression of the five stages of disease development is not obvious, or the three stages of fever, hypotensive shock and oliguria overlap (this type is critically ill and has a high mortality rate).
1. Fever period
The onset of fever is rapid, usually lasts 4-6 days, and a few patients have a fever period of up to 10 days. Patients develop symptoms related to infection toxicity, capillary damage, and kidney damage. After 4-6 days of fever, the patient's body temperature will return to normal, but other symptoms will worsen. Usually, the higher the patient's body temperature and the longer the fever cycle, the more serious the condition.
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Fever is the most common symptom in the early stage of the disease. The patient has symptoms of chills and high fever. The body temperature is 38-40 ℃, and the fever pattern is irregular, which usually lasts for 4-6 days. Most patients will experience "three pains", namely headache, low back pain, and orbital pain. Some patients will have symptoms such as loss of appetite, nausea, vomiting, abdominal pain, and diarrhea.
On the 2nd to 3rd day of the onset of hemorrhagic fever with renal syndrome, the patient may have "three red" symptoms, that is, the conjunctiva of the eyeball and the skin of the face, neck and upper chest are congested and flushed, like drunkenness. In addition, some patients may also experience mucosal bleeding and skin bleeding. Patients with severe symptoms may even experience hemoptysis, blood in the stool, hematuria, and intracranial hemorrhage.
The edema caused by hemorrhagic fever with renal syndrome during the febrile period is systemic, and the characteristic manifestations of ocular conjunctival edema will appear in the early stage of the disease. The severity of the disease varies with the degree of edema.
In the febrile period of hemorrhagic fever with renal syndrome, the manifestations of kidney damage such as proteinuria, hematuria and decreased urine output may occur. A large amount of urinary protein can appear in the early stage, and the urinary protein often reaches 3 to 4 "+", and some patients may appear membranous in the urine. Some patients experience pain in the kidney area.
2. Hypotensive shock period
On days 3 to 7 of the onset of hemorrhagic fever with renal syndrome, patients experience hypotension or hypotensive shock that lasts for hours to days. The main manifestations of hypotensive shock are:
● Blood pressure dropped significantly, heart rate, pulse increased. The decrease in systolic blood pressure in adults can be more than 40 mmHg lower than the baseline blood pressure or less than 2 standard deviations of the normal blood pressure for the same age;
● The patient's complexion, lips are pale or cyanotic, the limbs are cold, and the skin is mottled;
● Initially the patient will appear irritable and then will progress to lethargy, lethargy or coma;
● The patient has oliguria or anuria;
● Central venous pressure decreased.
The earlier the clinical manifestations of hypotensive shock appear and the longer the duration, the more severe the patient's condition is. Some patients after anti-shock treatment, still can not reverse the shock symptoms, it will turn into refractory shock. Refractory shock has an extremely poor prognosis and is one of the leading causes of death in patients with hemorrhagic fever with renal syndrome.
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3. Oliguria period
As mentioned earlier, some patients with hemorrhagic fever with renal syndrome do not have a complete five-stage clinical process, or they will have symptoms of oliguria and anuria during the shock stage. There is no very clear boundary, and the two phases can overlap or be completely absent.
On the 5th to 8th day of the onset, the patient enters the oliguria period, and the urine output in 24 hours is less than 400ml, which is oliguria. Can last 2-5 days. The clinical manifestations of the oliguria phase of hemorrhagic fever with renal syndrome are similar to those of acute renal failure due to other causes, but the hypervolemic syndrome and bleeding are more pronounced, and metabolic acidosis and hypokalemia are less severe. Oliguria or anuria suggests that the patient has developed acute renal failure. Patients at this stage often have symptoms such as anorexia, nausea, vomiting, abdominal distension, and dry mouth.
Patients with severe azotemia may be complicated by renal encephalopathy, and the patient may experience headache, lethargy, irritability and even coma. Patients with hemorrhagic fever with renal syndrome in the oliguria stage have aggravated bleeding from the skin and mucous membranes, and severe patients will have symptoms such as hemoptysis, blood in the stool, and hematuria. Due to the further aggravation of bleeding, patients with an oliguria period that lasted for more than 7 days often developed symptoms of anemia and combined with varying degrees of hypertension.
4. Polyuria
On the 9th to 14th day of the onset of the disease, enter the polyuria period, which lasts for about 7-14 days. With the increase of urine output, the patient's renal function will gradually recover, and the symptoms of uremia and the poisoning caused by it will gradually ease. However, it should be noted that if the patient excretes too much urine and does not replenish water and electrolytes in time, dehydration, hypokalemia and hyponatremia are prone to occur, and even shock may occur, resulting in secondary renal failure, severe Can be life-threatening.
5. Recovery period
In the third to fourth week of the onset of hemorrhagic fever with renal syndrome, the patient's condition begins to recover. The recovery period is generally 1-3 months, and the recovery period for severe cases is slightly longer. The criteria for entering the recovery period are: 24-hour urine volume <2000ml (24-hour urine volume in children <400ml/m2), and blood urea nitrogen and creatinine values are close to normal levels.
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Beware of Complications of Hemorrhagic Fever with Renal Syndrome
In the early stage of hypotensive shock, oliguria and polyuria, patients often experience a variety of complications, including massive hemorrhage (such as gastrointestinal hemorrhage, renal rupture hemorrhage, intracranial hemorrhage, pulmonary hemorrhage, etc.), pulmonary edema, and damage to the central nervous system. , Severe water and electrolyte acid-base balance disorders, heart failure and infection.
A series of complications caused by hemorrhagic fever with renal syndrome, in turn, will aggravate the condition, and at the same time, the critical symptoms caused by the complications will endanger the life of the patient.
5. How is hemorrhagic fever spread?
Three conditions must be met for an infectious disease to cause an epidemic, namely the source of infection, the route of transmission and the susceptible population. The epidemic of hemorrhagic fever with renal syndrome also requires these three conditions.
Source of infection
The source of infection refers to the human or animal (the host of the virus and other pathogens) that has pathogens such as viruses to survive and reproduce in the body, and can excrete the pathogens, including patients, pathogen carriers and infected animals.
The host of Hantavirus is very wide, about 200 kinds of animals can be infected with Hantavirus, and rodents are an important source of infection for the spread and prevalence of hemorrhagic fever with renal syndrome. Most of the infection sources of the popular haemorrhagic fever with renal syndrome in my country are the black-lined agaric and the Rattus norvegicus.
In addition to wild animals carrying hantavirus, common livestock and poultry can also be infected with hantavirus. Since livestock and poultry have closer contact with people, they should not be taken lightly. Studies have shown that domestic cats are also an important source of infection for hemorrhagic fever with renal syndrome. Domestic cats in endemic areas of hemorrhagic fever with renal syndrome have high infection rates and virus carrying rates, and the detoxification time of feces, urine and saliva of domestic cats can be determined. up to 92 days.
In the early stage of hemorrhagic fever with renal syndrome, hantaviruses can be detected in the blood and urine of patients. Although there are cases of post-contact infection, humans are not the main source of infection for hemorrhagic fever with renal syndrome.
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way for spreading
The route of transmission refers to the route by which the pathogen leaves the source of infection and reaches another susceptible host. Transmission routes include insect vector transmission, air transmission, respiratory transmission, contact transmission, soil transmission, vertical transmission, etc. The main routes of transmission of hemorrhagic fever with renal syndrome include:
1. Insect vector bites spread
Mite bites are one of the transmission routes of hemorrhagic fever with renal syndrome. Chinese scholars have found that haemorrhagic fever with renal syndrome can be transmitted by the bites of both gambid mites and chiggers.
2. Respiratory transmission
The host animals of Hantavirus, such as mice, carry the virus in their saliva, urine and feces. These substances pollute the dust in the air and form aerosols. Aerosols containing Hantavirus can be transmitted through the respiratory tract and cause human infection. Areas where animals such as rodents are dense are often infected due to inhalation of the respiratory tract, and even lead to large-scale epidemics.
3. Digestive tract spread
Studies have found that at room temperature (15-20 °C), hantavirus can survive in food such as water, rice, and steamed bread for 48 hours. Mouse excrement carrying Hantavirus, such as saliva, urine and feces, can be infected through the oral cavity and gastrointestinal mucosa, causing gastrointestinal transmission and even causing a large-scale epidemic.
4. Contact transmission
Transmission through skin wound contact is also an important way to lead to the prevalence of hemorrhagic fever with renal syndrome. Rat bites and wounds that come into contact with substances containing hantavirus can become infected.
5. Vertical transmission
Pregnant women infected with Hantavirus and developing hemorrhagic fever with renal syndrome are generally in critical condition. The virus can pass through the placenta and infect the fetus, which is more harmful to the fetus, and can cause miscarriage, stillbirth or massive hemorrhage and cause maternal death.
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susceptible population
Susceptible population refers to a population that lacks immunity to a certain infectious disease, which makes it easy to lead to infection. Hemorrhagic fever with renal syndrome has a general susceptibility, and people of different occupations and ages can develop the disease, but the disease has obvious occupational clusters. For example, the main incidence group of hemorrhagic fever with renal syndrome in my country is farmers. 70%-80% of the patients are farmers, which is due to farmers working in the fields for a long time and having a higher chance of being exposed to rodent excrement infected with Hantavirus, coupled with poor hygiene habits, lack of awareness of protection and other reasons. Obvious occupational agglomeration.
6. Hemorrhagic fever = plague?
Since the source of infection of haemorrhagic fever with renal syndrome and plague are rodents, and both can cause epidemics and have similar symptoms, are these two diseases the same thing?
First of all, it should be clear that hemorrhagic fever is not plague. Although hemorrhagic fever with renal syndrome and plague are both natural foci of infectious diseases, and the main source of infection are rodents, but the cause, symptoms, level of infectious disease and treatment measures of both are There are obvious differences in such aspects.
1. Different causes
Hemorrhagic fever with renal syndrome is a disease caused by Hantavirus infection, which is transmitted by rodents such as rodents. The plague is a severe infectious disease caused by Yersinia pestis infection, mainly in rodents, marmots and other rodents.
2. Symptoms are different
The incubation period of hemorrhagic fever with renal syndrome is generally 7-14 days, and most patients have relatively abrupt onset. Clinically, high fever at 38-40°C often occurs, with systemic mucosal congestion, hemorrhage, edema, hypotensive shock and renal function damage. as the main performance. The incubation period of plague is significantly shorter than that of hemorrhagic fever with renal syndrome, usually 2-5 days. Patients with pneumonic plague also experience symptoms such as coughing, bloody sputum, and shortness of breath.
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3. Different levels of infectious diseases
The "Law of the People's Republic of China on the Prevention and Treatment of Infectious Diseases" stipulates that hemorrhagic fever with renal syndrome is a Class B infectious disease, and plague is a Class A infectious disease. Class B infectious diseases generally have a better prognosis through early detection, early diagnosis, and early treatment. Compared with hemorrhagic fever, plague is more contagious and has a relatively higher fatality rate.
4. Different treatment methods
The treatment of hemorrhagic fever with renal syndrome is mainly symptomatic treatment, lack of specific antiviral drugs. In the early stage of the disease, ribavirin antiviral therapy can be applied, and balanced salt solution, glucose solution, etc. can be infused at the same time to prevent and treat shock. Plague requires antibacterial treatment, such as intramuscular injection of streptomycin, chloramphenicol and other antibacterial drugs, and can also be treated with fluoroquinolones, third-generation cephalosporins and tetracyclines.
7. How to prevent hemorrhagic fever?
The main methods for the prevention and control of infectious diseases include controlling the source of infection, cutting off the route of transmission, and protecting susceptible populations. This set of prevention and control strategies is also applicable to the prevention and control of hemorrhagic fever with renal syndrome.
Control the source of infection
To control the source of infection of hemorrhagic fever with renal syndrome, scientific rodent control and rodent control should be done, personal protection should be paid attention to when rodent control, direct contact with rodents should be reduced, and rodents and their excrement should not be touched with hands. Do a good job in the disinfection of patient supplies and contaminated supplies. At the same time, it is necessary to develop good hygiene habits, and do a good job in food preservation and disinfection to prevent rodent excrement from contaminating food and tableware. Leftovers and leftovers must be fully heated before eating.
cut off the transmission route
Do a good job of killing and preventing mites, do not stack firewood in the housing of the epidemic area, and do a good job of killing. During the epidemic season of hemorrhagic fever with renal syndrome, personal protection should be done well. Gloves should be worn during field work to prevent skin damage. If skin damage occurs, the wound should be disinfected with iodophor in time to prevent Hantavirus from contacting through skin wounds. Spread infection. In addition, we should also pay attention to wearing a mask to reduce the transmission of dust aerosols contaminated by Hantavirus through the respiratory tract.
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Protect vulnerable populations
Develop good living habits, maintain personal hygiene, strengthen physical exercise, and improve immunity to diseases.
Is it necessary to inject inactivated hemorrhagic fever with renal syndrome vaccine?
The most effective way to prevent infectious diseases is to get vaccinated. Increasing the vaccination rate of hemorrhagic fever with renal syndrome vaccine can effectively control the incidence of hemorrhagic fever, and it is also an important measure to prevent hemorrhagic fever with renal syndrome. At present, the vaccine used in my country is the inactivated hemorrhagic fever vaccine with renal syndrome, which has a good protection effect on the population, and the protection rate can reach more than 95%.
The inactivated vaccination program for hemorrhagic fever with renal syndrome includes basic immunization and booster immunization. The basic immunization has 2 doses, and the second dose is given 14 days after the first dose. Booster immunization is a booster injection that should be injected 6 months or 1 year after the completion of the basic immunization. Because hemorrhagic fever with renal syndrome has an obvious peak incidence, in order to ensure the effect of the vaccine, the population in the foci can complete the whole injection of the vaccine within one month before the epidemic of hemorrhagic fever with renal syndrome.
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Although inactivated hemorrhagic fever vaccine with renal syndrome has important protective effects, vaccination coverage is generally low. The population should raise the awareness of vaccination, especially the population in the epidemic area, should complete the vaccination in time and on time.
As an acute viral infectious disease, hemorrhagic fever with renal syndrome poses great harm to the health and life safety of patients. If you have been to an epidemic area, or have suspicious symptoms of hemorrhagic fever with renal syndrome, such as unexplained fever and hemorrhage, you should avoid taking chances and seek medical treatment in time.
Author: Zhang Jing
Text review: Bai Shuangling
Scientific review: Lu Haiying, chief physician of the Department of Infectious Diseases, Peking University First Hospital
This article comes from: China Digital Science and Technology Museum
https://www.cdstm.cn/gallery/zhuanti/ptzt/202201/t20220114_1063257.html
