Engaged in wild bird photography for a long time.

I won't. The name bird flu may be a little strange to ordinary people. Because it was called chicken plague for a long time in the past, it was first reported in 1878 Italy. 190 1 year confirmed that the pathogen was a viral pathogen, and 1955 confirmed that the pathogen was a member of influenza A virus. Later, it was found that there were similar diseases in birds, called Newcastle disease. The two are often confused.

In order to distinguish the two, the former is called avian influenza or true chicken plague, European chicken plague, and the latter is called Newcastle disease or pseudo chicken plague and Asian chicken plague. Therefore, avian influenza is an acute infectious disease caused by influenza A virus.

According to different pathogenicity, avian influenza viruses can be divided into three categories: high pathogenicity, low pathogenicity and non-pathogenicity. Highly pathogenic avian influenza has been listed as a kind of animal disease by the World Organization for Animal Health because of its rapid spread and great harm, and it is listed as a kind of animal disease in China.

2. What is the relationship between avian influenza virus and influenza virus?

What we usually call influenza is an acute respiratory infectious disease caused by influenza A (A), B (B) and C (C) viruses. Type A and B, especially type A, can cause human influenza epidemic, while type C only causes sporadic cases. Avian influenza is caused by influenza A virus.

Influenza A virus has two surface antigens, hemagglutinin (H) and neuraminidase (N), which can be further subdivided. H can be divided into H 1 ~ H 15, and n can be divided into N 1 ~ N9. Different hemagglutinins and different neuraminidase will form influenza viruses with different antigenicity and pathogenicity, which are called influenza virus subtypes in technical terms.

There are 145 subtypes of influenza A virus, among which H 1 ~ H3 is the main type that can cause human influenza, and H 1N 1, H2N2 and H3N2 have caused human influenza epidemic. The natural hosts of most other subtypes are birds, pigs, horses and other animals, especially waterfowl. All antigens of H 1 ~ H 15 and N 1 ~ N9 subtypes can be isolated from animals.

3. What factors determine whether influenza will become an epidemic?

The biggest feature of influenza virus is antigen variability, which can cause changes in transmission. Among them, type A antigen has the strongest variability, and small variation often occurs, which is called "antigen drift". The degree of influenza virus variation is different, and the degree of epidemic is also different. When the influenza virus has a large variation or subtype transformation, it is called "antigen transfer", which may cause a worldwide influenza epidemic. Comparatively speaking, the variability of type B is weak, which will only cause outbreaks and epidemics in local areas; Type C is relatively stable and only causes sporadic cases. Therefore, influenza A virus is the focus of human research, prevention and control.

4. What is the drug resistance of avian influenza virus?

Avian influenza virus can survive for several months to more than one year in low temperature, dryness and glycerol. In dry dust, the virus can survive for 14 days. At low temperature, the virus survived in contaminated feces for at least 3 months. In water, it can survive for 4 days at 22℃ and for more than 30 days at 0℃. It can survive in frozen poultry meat and bone marrow for 10 month. Avian influenza virus is afraid of sunlight, heat and common disinfectants. Under direct sunlight, it can be inactivated in 40-48 hours. The virus can be killed by heating (60℃ for 30min, 100℃ 1 min) or common disinfectants (formalin, complex iodine, etc.). ).

5. Why is human avian influenza a new infectious disease?

Although bird flu has been prevalent in birds and other animals for more than 100 years, there has never been a report of human infection before. During the period of 1997, there were 18 cases of avian influenza in Hong Kong, among which 6 people died. The virus strains of this human avian influenza epidemic are consistent with those of Hong Kong poultry at that time, both of which are H5N 1 type. This is the first time that bird flu has infected humans. Therefore, avian influenza is a newly discovered infectious disease.

Transmission characteristics of avian influenza

6. What is the source of infection of avian influenza?

The source of infection refers to animals and people who have pathogens living and reproducing in their bodies and can excrete pathogens. The main sources of infection of avian influenza are sick birds and infected birds, including waterfowl and flying birds. Studies have shown that for highly pathogenic avian influenza, the virus content in 1 g contaminated feces can cause 1 10,000 birds to be infected. At present, people cannot be considered as the source of infection of avian influenza.

7. What are the susceptible animals of avian influenza?

Animals that are infectious to infectious diseases are called susceptible animals. Chickens, turkeys, ducks, geese, quails, pheasants, partridges, ostriches, pigeons and peacocks are all susceptible to avian influenza. Chickens and turkeys are the most sensitive, and waterfowl such as ducks and geese are mostly recessive infections. Co-raising waterfowl and dry birds in the same site will cause cross-infection, and the virus can easily spread between chickens or ducks raised on a large scale. Wild and farmed waterfowl can spread through ordinary water bodies.

Besides infecting birds, bird flu can also infect pigs.

8. How does bird flu spread among birds?

Avian influenza is mainly transmitted through contact with infected birds and their secretions and excretions, contaminated feed, water, egg plates (boxes), padding, eggs, chicken embryos and semen. , through respiratory and digestive tract infections, but also through air-borne media.

In nature, birds carry the most viruses, so migratory birds, wild birds and waterfowl with a wide range of migration play an important role in the spread of diseases. It is not clear whether the parasitic insects on the surface of poultry are also toxic, and biting people can also be infected.

9. How did the avian influenza virus spread to humans?

Avian influenza virus can enter the human body through the digestive tract and respiratory tract and infect people. If you come into direct contact with articles with a considerable amount of viruses, such as poultry droppings, feathers, respiratory secretions, blood, etc. It can also cause infection through conjunctiva and broken skin.

10. Who are the high-risk groups of avian influenza?

Veterinarians and people who have been engaged in raising, selling and slaughtering chickens, ducks, geese and pigs for a long time.

1 1. Will bird flu spread from person to person?

At present, only human-to-human cases transmitted by poultry have been found, and no human-to-human cases have been found. In other words, there is no evidence that people can infect each other. However, WHO warns that theoretically, if the virus mutates, it may spread from person to person.

12. How is bird flu spread in some areas?

Bird flu can easily spread from one farm to another. Bird droppings can contain a large number of viruses, causing dust and soil pollution, and then spread among birds through the air. The virus spreads from one farm to another by polluting equipment, means of transport, feed, cages, clothes and especially shoes. Viruses can also spread through the feet and bodies of animals (such as rodents). Live birds are traded in crowded markets, and the sanitary conditions are poor, which is also a mode of transmission. At present, the ability of flies to spread this virus has not been confirmed.

13. How does bird flu spread over a long distance?

Bird flu can spread from one country to another through the international trade of live birds. Migratory birds, including wild waterfowl, seabirds and shorebirds, can carry viruses over long distances. Wild ducks are the most striking natural hosts of avian influenza virus, and they have strong resistance to virus infection, sometimes with mild and non-fatal symptoms, but they can carry the virus from a long distance and excrete the virus through feces. People raise ducks, turkeys, geese and other poultry for commercial and domestic use, which will lead to fatal infections. Free movement of poultry, sharing water sources with wild birds or using water sources that may be contaminated by feces of infected wild birds are the most dangerous for virus transmission.

14. Will eating cooked poultry and eggs get infected?

The main route of human infection with avian influenza virus is contact infection. After the poultry meat is cooked, the virus can be killed and the possibility of transmission is very small. At present, no cases of infection caused by eating poultry meat and eggs have been found. However, if sick birds are not cooked and eaten thoroughly, the virus may enter the human body. Therefore, if you eat poultry that have not been quarantined or come from epidemic areas, you will not rule out the risk of illness.

15. Is it contagious to buy live chickens home?

If it is a healthy live chicken, it is basically safe. If it is a sick chicken, it is dangerous. WHO warns that no matter what kind of sick chickens people come into contact with, they are equally dangerous. A few infected poultry can survive, but they will excrete virus-containing feces for at least 10 days. In addition, the chicken wings may contain avian influenza virus, so the virus may be released when the chicken wings flap.

16. Will down products spread avian influenza?

Down products are usually treated by disinfection and high temperature, so the probability of spreading the virus should be very small.

Clinical manifestations of avian influenza

17. How long is the incubation period of avian influenza?

The incubation period refers to the period from the invasion of pathogens into the body to the appearance of initial symptoms. The incubation period of avian influenza in poultry ranges from several hours to several days, and the longest incubation period can reach 2 1 day. After human infection with avian influenza, the incubation period usually does not exceed 7 days.

18. What are the manifestations of avian influenza infection in poultry?

There are two forms of post-infection diseases in poultry:

Low-pathogenic avian influenza only causes mild symptoms, and sometimes it only manifests as wrinkled feathers, disorder and decreased egg production.

Birds suffering from highly pathogenic avian influenza can suddenly die, with high mortality rate, and the consumption of feed and drinking water and the amount of eggs dropped sharply. Sick chickens are extremely depressed, head and face edema, cockscomb cyanosis, foot scale bleeding and nervous disorder. Waterfowl such as ducks and geese have obvious neurological and diarrhea symptoms, which can cause corneal inflammation and even blindness.

Once the above symptoms are found in poultry farms, it can be suspected to be highly pathogenic avian influenza.

19. What are the symptoms of human suffering from avian influenza?

After human suffering from avian influenza, the early symptoms are very similar to severe influenza, such as high fever, runny nose, stuffy nose, cough, sore throat, headache and general malaise. Some patients may have digestive tract symptoms, such as nausea, abdominal pain, diarrhea and watery stools. Some patients can see eye infections such as conjunctivitis, and most patients' body temperature is above 39℃. Some patients will have unilateral or bilateral pneumonia on chest radiograph, and a few patients will have pleural effusion. Some patients may develop acute respiratory distress syndrome and other serious life-threatening syndromes. The mortality rate of human suffering from avian influenza is as high as over 30%.

Diagnosis and treatment of avian influenza

20. How to diagnose poultry avian influenza in the laboratory?

When collecting live poultry samples, cloacal swabs and tracheal swabs can be used for sampling. When collecting dead bird samples, tissues and organs such as trachea, spleen, lung, liver, kidney and brain should be collected. For small rare birds, fresh feces should be collected.

Laboratory examination includes etiological diagnosis and serological examination. Etiological examination includes pathogen isolation, gene identification and virulence determination. Serological diagnosis mainly includes agar gel immunodiffusion test (not suitable for waterfowl) and hemagglutination inhibition test (H 1).

2 1. How to confirm avian influenza in poultry?

According to the Emergency Notice on Strengthening the Prevention and Control of Highly Pathogenic Avian Influenza issued by the Ministry of Agriculture on June 28, 2004, the epidemic situation of highly pathogenic avian influenza in China was confirmed according to the following procedures:

① After receiving the epidemic report, the provincial animal husbandry and veterinary department sent more than 2 avian influenza experts to the scene for clinical diagnosis. If the clinical symptoms are obvious, it can be suspected that it is a highly pathogenic avian influenza epidemic.

② When the epidemic situation of highly pathogenic avian influenza is suspected, collect samples in time and send them to provincial laboratories for serological testing. If the diagnosis result is positive, it can be identified as a suspected case of highly pathogenic avian influenza.

③ Suspected cases should be sent to the National Avian Influenza Reference Laboratory for further identification, and specimens should not be mailed.

The National Reference Laboratory of Avian Influenza conducts pathogen isolation and identification on the sick materials reported by all provinces, autonomous regions and municipalities directly under the Central Government, and reports the conclusions to the Ministry of Agriculture.

22. What is the diagnostic basis of human avian influenza?

The diagnostic principle of human avian influenza is comprehensive analysis and diagnosis based on epidemiology, clinical symptoms and laboratory examination. Referring to the Diagnostic Criteria and Prevention Guidelines for New and Recurrent Infectious Diseases edited by Enshi, the diagnosis basis is as follows:

(1) Epidemiological history: Avian influenza occurred before, that is, a large number of birds (chickens, ducks, geese, etc.) appeared in a poultry farm. ) developed bird flu-like symptoms in a certain area and died; There is an epidemic or outbreak of avian influenza in the vicinity or surrounding areas.

② Clinical manifestations include sudden onset, fever (above 38℃), cough, sore throat, headache, dizziness, general aches, fatigue and other poisoning symptoms, accompanied by respiratory symptoms such as dry cough, runny nose and tears. A few cases have anorexia, accompanied by gastrointestinal symptoms such as abdominal pain, abdominal distension and vomiting.

③ Laboratory examination isolated influenza virus from nasopharyngeal or tracheal secretions of patients; The titer of anti-influenza virus antibody in serum of convalescent patients is more than 4 times higher than that in acute stage. The specific protein components or specific nucleic acids of influenza virus particles were found in the respiratory epithelial cells of patients; After the virus was propagated by sensitive cells for one generation, the specific protein or specific nucleic acid of influenza virus particles was found.

At present, there is no unified standard for the classification of human avian influenza cases in China, and the Ministry of Health is organizing the formulation.

23. Do birds need treatment after being infected with avian influenza?

At present, there is no reliable treatment for avian influenza. After birds are infected with avian influenza, they must be thoroughly culled to prevent the spread of the epidemic.

24. What do you think of human infection with avian influenza?

① General treatment should be based on respiratory isolation 1 week or until the main symptoms disappear. Patients need to stay in bed, drink plenty of water, have proper nutrition, supplement multivitamins and keep their nasopharynx and mouth clean. Those with severe symptoms should be hospitalized. Antibiotics are only used when bacterial complications occur.

② Patients with high fever and headache can be treated with physical cooling or antipyretic sedatives, and aspirin is forbidden in children. Patients with high fever and vomiting should be given intravenous rehydration. People who cough and expectorate can take antitussive and expectorant drugs.

③ Take amantadine and rimantadine, anti-influenza drugs. Amantadine and rimantadine are inhibitors of virus M2 protein, which are effective for influenza A, blocking the virus's adsorption to sensitive cells. Usually taking medicine within 48 hours of onset can reduce the amount of virus discharged, shorten the time of detoxification, relieve clinical symptoms, reduce fever within one or two days, prevent infection from spreading to the lower respiratory tract and reduce the occurrence of pneumonia. Za-Nimivir and oseltamivir are neuraminidase inhibitors, which can resist influenza A and B viruses.

25. Can people get bird flu and be cured?

Most patients can be cured after timely treatment. Short course of disease, quick recovery and no sequelae. A few patients, especially those who are older and treated too late, develop rapidly, and patients may die of various complications such as progressive pneumonia, acute respiratory distress syndrome, pulmonary hemorrhage, pleural effusion, pancytopenia, renal failure, sepsis and shock. Therefore, once the patient has the above symptoms, he should seek medical attention in time. Once you are suspected of being infected with H5N 1 virus, you should be hospitalized immediately for isolation treatment and report the epidemic situation to prevent the disease from getting worse and spreading.