Does bird flu have an incubation period?

First, the concept, incidence and epidemic characteristics of highly pathogenic avian influenza

1. What is avian influenza? What is highly pathogenic avian influenza?

Avian influenza is short for avian influenza. It is an infectious disease of poultry (poultry and wild birds) caused by influenza A virus. Avian influenza virus infection can show mild respiratory symptoms and digestive symptoms, with low mortality; Or more serious systemic, hemorrhagic and septic symptoms, and the mortality rate is higher. This difference in symptoms is mainly determined by the virus type of avian influenza.

According to the different pathogenicity of avian influenza, avian influenza can be divided into highly pathogenic avian influenza, low pathogenic avian influenza and non-pathogenic avian influenza. Recently, avian influenza caused by H5N 1 serotype is called highly pathogenic avian influenza at home and abroad, with high morbidity and mortality and great harm.

2. How long is the incubation period of highly pathogenic avian influenza? Is the incubation period contagious?

The incubation period of avian influenza varies from several hours to several days, and the longest incubation period can reach 2 1 day. The incubation period is affected by many factors, such as virus virulence, infection times, poultry resistance, age and species, feeding management, nutritional status, environmental sanitation and emergency. Highly pathogenic avian influenza has short incubation period, rapid onset and high morbidity and mortality. There is the possibility of infection in the incubation period.

3. What is the transmission route of avian influenza?

There are two modes of transmission of avian influenza: direct contact between sick birds and healthy birds and indirect contact with virus pollutants. Avian influenza virus exists in the digestive tract, respiratory tract and organs of sick and infected birds. Therefore, the virus can be excreted with the secretions and feces of eyes, nose and mouth, and any object contaminated by the secretions and feces containing avian virus, such as feed, drinking water, chicken coops, air, cages, feeding management tools, transport vehicles, insects and various birds carrying viruses, can be spread mechanically. Healthy birds are infected through respiratory tract and digestive tract, causing diseases.

4. What are the main clinical manifestations of highly pathogenic avian influenza? What's the difference between Newcastle disease and general Newcastle disease?

Acute infection with avian influenza has no specific clinical symptoms. In a short period of time, it may lead to loss of appetite, a sharp rise in body temperature, a high degree of mental depression and a large number of deaths. There are obvious differences between Newcastle disease virus infection and avian influenza. Their virus types are different. Avian influenza is orthomyxoviridae, and Newcastle disease is paramyxovirus. The typical clinical symptoms of Newcastle disease virus infection can be seen in the early stage: long incubation period, respiratory symptoms, diarrhea, loss of appetite, listlessness, and neurological symptoms in the later stage.

5. What are the epidemic characteristics of highly pathogenic avian influenza?

Highly pathogenic avian influenza virus is similar to common influenza virus, which can be prevalent all year round, but it is easy to be prevalent in winter and spring, so avian influenza virus has strong resistance at low temperature. All kinds of birds of different ages can be infected with highly pathogenic avian influenza, which has an urgent onset and rapid spread, and the mortality rate can reach 100%.

6. Is the occurrence of highly pathogenic avian influenza related to the age, sex and species of poultry?

Chickens, turkeys, guinea fowl, quails, ducks and geese can be infected, but chickens, turkeys, ducks and geese are more common, among which turkeys and chickens are the most susceptible, with higher morbidity and mortality. Waterbirds such as ducks and geese have low susceptibility, but they can be infected with viruses or recessive infections, and sometimes they die in large numbers. Chickens and turkeys of all ages can be infected and die, but the mortality rate of waterfowl such as ducklings and goslings is higher. It has not been found that the occurrence of highly pathogenic avian influenza is related to the sex of poultry.

7. Will highly pathogenic avian influenza spread through eggs?

The spread of highly pathogenic avian influenza among birds mainly depends on horizontal transmission, such as air, feces, feed and drinking water. There is little evidence of vertical transmission. However, experiments show that the eggs infected with chickens contain influenza virus, so the possibility of vertical transmission cannot be completely ruled out. You can't hatch with contaminated chicken eggs.

8. Why does highly pathogenic avian influenza occur in winter and spring?

Highly pathogenic avian influenza can occur all year round, but it occurs frequently in winter and spring. The main reasons are:

First of all, influenza virus is very sensitive to temperature. With the increase of environmental temperature, the survival time of the virus is shortened. In addition, the light intensity is relatively high in summer and autumn, and the ultraviolet rays in the sun have a strong killing effect on the virus.

Secondly, the ventilation intensity of poultry houses in summer and autumn is much higher than that in winter and spring. Good ventilation can greatly reduce the number of viruses in the henhouse environment. Therefore, the chances and quantity of virus invading chickens are obviously reduced, and the infection probability is reduced. At the same time, good ventilation also reduces the stimulation of bad gas to the respiratory mucosa of chickens, which is of great significance to maintain the resistance of respiratory mucosa.

Two. Measures to prevent and control highly pathogenic avian influenza

9. Is there a vaccine to prevent highly pathogenic avian influenza?

China has successfully developed a vaccine to prevent H5N 1 highly pathogenic avian influenza. Farms in non-epidemic areas should be vaccinated in time to prevent the occurrence of bird flu.

10. Should highly pathogenic avian influenza be treated?

When highly pathogenic avian influenza occurs in poultry, there is no good treatment at present because of its acute onset, high incidence and high mortality. According to national regulations, birds within three kilometers should be culled and buried immediately after being diagnosed as highly pathogenic avian influenza, and their pollutants should be treated harmlessly. This can put out the epidemic as soon as possible, eliminate the source of infection and reduce economic losses. This is one of the effective means to fight bird flu and should be resolutely implemented.

1 1. How should poultry houses, pollutants and their environment be disinfected?

Influenza virus can pollute poultry houses, cages, padding and so on with the excretion of feces and nasal secretions from infected birds. Influenza viruses are sensitive to disinfectants and heat. When the contaminated poultry house is disinfected, it must be cleaned with detergent to remove dirt, then disinfected with sodium hypochlorite solution, and finally fumigated with formalin and potassium permanganate. Iron cages can also be disinfected with flame. Due to the high virus content in feces, special attention should be paid to the treatment. Feces and bedding should be buried, and the tools used for treatment should be soaked in caustic soda water or other disinfectants for disinfection.

12, which disinfectants can effectively kill avian influenza virus? How to use it?

Avian influenza virus has poor viability in the external environment. As long as proper disinfection measures are taken, disinfectants commonly used in poultry production practice, such as aldehydes, chlorine-containing disinfectants, phenols, oxidants and alkalis, can kill viruses in the environment. The following disinfectants have good disinfection effect in the field environment:

(1) Aldehyde disinfectants include formaldehyde and paraformaldehyde, among which formaldehyde fumigation is the most commonly used. Closed pens can be fumigated and disinfected with 7-2 1 g potassium permanganate and 14-42 ml formalin per cubic meter. During fumigation and disinfection, the room temperature is generally not lower than 65438 05℃ and the relative humidity is 60%-80%. Potassium permanganate can be added to the container first, then formalin solution can be added, and the doors and windows can be sealed for more than 7 hours to achieve the purpose of disinfection, and then the doors and windows can be opened for ventilation to eliminate residual odor.

(2) The disinfection effect of chlorine-containing disinfectants depends on the content of available chlorine. The higher the content, the stronger the disinfection ability, including inorganic chlorine-containing disinfectants and organic chlorine-containing disinfectants. 5% bleaching powder solution can be sprayed on animal pens, cages, feeding troughs and vehicles for disinfection. Hypochloric acid disinfection is rapid, no residue, no odor, and is often used for disinfection of equipment and countertops in food factories and slaughterhouses.

③ Alkaline preparations mainly include sodium hydroxide. Sodium hydroxide preparations used for disinfection are mostly crude alkali liquor containing 94% sodium hydroxide, which is often heated to prepare 1%-2% aqueous solution, which is used for disinfection of chicken coops, walls, sports fields and pollutants contaminated by viruses, as well as for disinfection of slaughterhouses, food factories and other ground and transportation vehicles. After spraying for 6- 12 hours, rinse with clean water.

13. Will the mixed culture of chickens, ducks, geese and pigs lead to the occurrence of highly pathogenic avian influenza?

Poultry should not be mixed with pigs, because poultry influenza virus can infect pigs, and human influenza virus can also infect pigs. Because influenza virus has eight different nucleic acid fragments, when these two different virus particles infect a cell, their nucleic acid fragments will be rearranged to produce new influenza virus particles, which can often form a big epidemic for human beings and cause great harm.

In addition, chickens should not be mixed with ducks, geese and other waterfowl, so the carrying rate of various subtypes of influenza virus in waterfowl is very high, and some do not show any clinical symptoms. After the virus in their feces infects chickens, it can cause the occurrence and epidemic of avian influenza, resulting in serious economic losses.

14. Is it useful to strengthen poultry feeding management to prevent avian influenza?

Strengthening feeding management is the premise of preventing all animal infectious diseases. Only under good feeding management can poultry be guaranteed to be in the best growth state and have good disease resistance. From the perspective of preventing avian influenza, we must consider feeding management and disease prevention as a whole, and take strict management measures, such as isolating farms and pens, disinfecting the environment, controlling the flow of people and goods, etc., to prevent birds from being harmed by diseases.

15. How to prevent highly pathogenic avian influenza?

Comprehensive preventive measures must be taken to prevent bird flu. The farm is far away from residential areas, bazaars, traffic arteries and other animal production sites and related facilities; Do not introduce breeding eggs and poultry from epidemic areas; Strictly disinfect passing vehicles and surrounding environment, incubation halls, incubators, chicken coops, clothes and shoes of staff. Adopt all-in and all-out feeding methods to prevent contact between birds and birds; The farm should have a special passage for the staff to enter and exit, and the staff and their daily protective equipment should be cleaned and disinfected reliably; It is strictly forbidden for all outsiders to enter or visit the animal farm area. In areas threatened by highly pathogenic influenza, vaccination should be carried out under the guidance of the local veterinary health management department, and serological monitoring should be carried out regularly to ensure the reliable immune prevention effect of the vaccine.

16. How to prevent highly pathogenic avian influenza in hatcheries and hatcheries?

First of all, the design of incubator should be done well. It should be a one-way traffic route from the egg feeding room, egg loading room, hatching room, waiting room, 1 day-old chick loading workshop to the loading area of the transport vehicle. Each incubator must be conducive to thorough cleaning and disinfection, and the ventilation system should be able to prevent the recirculation of polluted air and dust.

The second is to do a good job in the inspection and timely disinfection of eggs. Breeders should collect eggs regularly after laying eggs, remove dirt on the surface in time, and eliminate eggs that are seriously polluted and cracked.

Third, do a good job in cleaning and disinfecting incubators, egg trays, eggs and incubators before hatching.

Fourth, thoroughly disinfect the vehicles and equipment transporting young birds to prevent cross-infection.

Fifth, under the guidance of the local veterinary health management department, breeders are immunized, and chicks are also immunized.

17. Is there a relationship between poultry feeding methods and highly pathogenic avian influenza?

Feeding methods are closely related to the occurrence and control of avian influenza, and good feeding management conditions are the key to prevent avian influenza.

Avoid the mixed culture of chickens and waterfowl. Waterfowl is one of the important storage hosts of avian influenza virus, which can carry the virus without necessarily getting sick, but it can excrete the virus through feces, polluting water sources or the environment. These viruses may infect chickens and other poultry raised at the same time, causing them to get sick.

Therefore, grazing or stocking families are more likely to come into contact with other birds, migratory birds or the environment, feed and drinking water polluted by these wild animals, and the probability of contracting avian influenza is greatly increased.

Intensive poultry is less likely to be infected with avian influenza because of good environmental isolation conditions, strict personnel and logistics control, and good veterinary health and epidemic prevention measures, and once it happens, control measures can be taken quickly.

18. What is the recommended immunization program for highly pathogenic avian influenza?

In the event of an epidemic, susceptible birds within 5 kilometers around the epidemic area must be vaccinated urgently, and an immune isolation belt should be established around the epidemic area. Vaccination is only used for healthy chickens that are not infected with highly pathogenic avian influenza virus. Emergency immunization must be carried out under the guidance of veterinary personnel.

19. Can birds with highly pathogenic avian influenza heal themselves?

I can't. When highly pathogenic avian influenza virus infects, the morbidity and mortality can reach 100%.

20. Why should poultry within a radius of 3 kilometers around the highly pathogenic avian influenza epidemic be culled?

In China, highly pathogenic avian influenza is classified as an epidemic area within a radius of 3 kilometers around the epidemic spot, because poultry within a radius of 3 kilometers around the epidemic spot are the most susceptible to infection. In order to ensure that the epidemic situation of highly pathogenic avian influenza can be completely extinguished, it is absolutely necessary to cull all the poultry around the epidemic spot and within 3 kilometers. This will help to control the spread of pathogens caused by sick birds and their droppings, sewage and other pollution sources. This is the most effective way to control serious infectious diseases, and it is also an international practice.

2 1. Why should culled poultry be treated harmlessly?

Because culled poultry may contain highly pathogenic avian influenza virus, if these pathogens are not eradicated, allowing sick poultry to flow into the market will inevitably lead to the spread of highly pathogenic avian influenza virus and may endanger the health of consumers. In order to ensure the health of consumers and effectively control epidemics, culled poultry must be burned and buried harmlessly.

22. Why should the highly pathogenic avian influenza epidemic area be blocked?

Isolation and blockade of highly pathogenic avian influenza epidemic areas as soon as possible can prevent highly pathogenic influenza virus from spreading from epidemic areas to non-epidemic areas, prevent the epidemic from further expanding, and reduce the major economic losses and international impact caused by highly pathogenic avian influenza.

23. When highly pathogenic avian influenza occurs, why should the focus be tracked?

Because timely and thorough elimination of the epidemic source is the key to control highly pathogenic avian influenza. When highly pathogenic avian influenza occurs, it is necessary to report the epidemic situation in time, find the epidemic spot as soon as possible, block the epidemic spot and cull poultry in a short time, which can effectively prevent the spread and spread of avian influenza epidemic.

24. What is the time limit for lifting the blockade?

The longest incubation period of avian influenza is 2 1 day, during which new cases of avian influenza virus infection may occur at any time. Only when there are no new cases of infection in an incubation period can it be proved that there is no avian influenza virus in the blocked area. After the blockade is lifted, it can be guaranteed that there will be no new highly pathogenic influenza epidemic in this area, thus achieving the purpose of extinguishing the epidemic. Therefore, the blockade of highly pathogenic avian influenza epidemic areas can only be lifted after the last poultry is culled for at least one incubation period.

25. What are the criteria for fighting the epidemic?

The standard for exterminating the epidemic situation is that after the last batch of cases in the epidemic area were culled and thoroughly disinfected, there were no new cases of avian influenza for at least 2 1 day, indicating that the epidemic situation in this area has been exterminated.

26. Why should we monitor the epidemic situation of migratory birds?

Avian influenza virus can infect many kinds of wild birds, especially migratory waterfowl. Facts have proved that migratory birds are often the real source of the spread of avian influenza pathogens. Therefore, it is very useful to strengthen the epidemic monitoring of migratory birds to find the focus of avian influenza. The large-scale simultaneous outbreak of avian influenza in many Asian countries is not unrelated to the migration of migratory birds.

27. How can chickens and ducks raised by farmers on a small scale prevent bird flu?

Attention should be paid to the cleanliness of the henhouse and consciously accept the monitoring of the supervising agencies for animal epidemic prevention. If you are in an area threatened by bird flu, you should give effective vaccines to chickens and ducks. Once the suspected highly pathogenic avian influenza epidemic situation is found, it should be reported to the local supervising agency for animal epidemic prevention immediately, and measures should be taken to block and isolate the epidemic spots to prevent the epidemic from spreading.

Third, the identification method of highly pathogenic avian influenza

28, at present, what are the research results of highly pathogenic avian influenza?

Since the mid-1990s, China has done a lot of work in the epidemiology, diagnosis, immune control and basic research of avian influenza, and achieved many research results. In the aspect of avian influenza diagnosis technology, (1) agar diffusion (AGP) diagnosis technology was established. (2) Subtype typing technology. (3) Virus molecular diagnosis technology. Development of Avian Influenza Vaccine: An inactivated H5 subtype avian influenza vaccine has been developed, which can be used for emergency immunization of H5 subtype highly pathogenic avian influenza. H5N 1 subtype avian influenza recombinant fowlpox virus live vector vaccine has also entered the stage of regional safe release.

29. How long does it take to confirm the pathogen? Do what experiment?

Highly pathogenic avian influenza must be diagnosed by virus isolation and identification. Virus isolation and subtype identification generally take at least 3-5 days. The pathogenicity of the virus must be finally determined by artificial intravenous inoculation of non-specific pathogen chickens (SPF chickens).

30. The Ministry of Agriculture has issued technical specifications for the prevention and treatment of highly pathogenic avian influenza. What are the diagnostic criteria for highly pathogenic avian influenza?

According to the Notice of the Ministry of Agriculture on Printing and Distributing Seven Technical Specifications for the Prevention and Control of Highly Pathogenic Avian Influenza (Nongbanmu [2002] No.74), highly pathogenic avian influenza can be confirmed in the following cases: (1) The clinical symptoms and pathological changes are typical, the onset is urgent, the mortality rate is high, Newcastle disease and toxic diseases can be excluded, and the serological test is positive. (2) Avian influenza virus serotypes H5 and H7 were positive among the poultry in the non-immunized chicken farm. (3) Isolating H5 and H7 subtype avian influenza virus strains or other subtype avian influenza virus strains from poultry flocks.

Four, a correct view of highly pathogenic avian influenza

3 1. How to scientifically deal with highly pathogenic avian influenza?

People's research on avian influenza has a long history. The first case of avian influenza was found in 1878. The world has experienced 12 pandemics, which have occurred frequently in Asia in recent years. This highly pathogenic avian influenza is not an infectious disease caused by a new virus. In recent years, other countries and regions have also reported H5N 1 and H7N7 highly pathogenic avian influenza. After years of scientific research, there have been effective methods to control avian influenza. Epidemiological investigation proves that avian influenza is horizontal transmission. Cutting off its transmission route can control the epidemic spread of the disease. The virus is sensitive to high temperature, and can be inactivated at 60-70℃ for 2 minutes to 10 minutes. Cooked poultry meat, eggs and poultry products sold in the market can be safely eaten. There is no need to panic.

Is highly pathogenic avian influenza harmful to ordinary citizens?

Under normal circumstances, ordinary citizens will not be exposed to sick birds with highly pathogenic avian influenza, because the poultry and their products sold in the market have been inspected and quarantined by the veterinary health department, and sick birds and unqualified poultry products will not enter the market. Therefore, highly pathogenic avian influenza cannot directly pose a threat to ordinary citizens. On the other hand, poultry and poultry products are processed by boiling or barbecue for everyone to eat. In this process, the virus is completely destroyed and inactivated, and it is no longer contagious.

33. What should I do if I have contact with birds with highly pathogenic avian influenza?

First of all, don't panic, because after all, the probability of birds transmitting diseases to people is very low. In the place where the epidemic occurred in China, the health department has carried out medical examination and observation on people who are in close contact with sick birds, and no infection has been found. However, if you have contact with birds with highly pathogenic avian influenza, if you have cold-like symptoms, you should go to the hospital immediately and actively cooperate with doctors.

Verb (abbreviation of verb) and rules and regulations related to the prevention and treatment of highly pathogenic avian influenza

34. How should farmers cooperate with the government to do a good job in areas where highly pathogenic avian influenza occurs?

Highly pathogenic avian influenza is classified as a class A infectious disease by the World Organization for Animal Health (OIE), and it is classified as a class of animal infectious disease in China. Once the suspected highly pathogenic avian influenza occurs, the suspected sick birds shall be isolated and blocked according to the relevant laws and regulations of animal epidemic prevention in China, and further diagnosed. When it is confirmed to be highly pathogenic avian influenza, the epidemic area should be blocked immediately, the sick birds should be culled and the environment should be thoroughly disinfected to prevent the epidemic from spreading further. While the government takes measures, farmers should also actively cooperate. Although it will cause certain losses to farmers, it is necessary to focus on the overall situation and prevent the spread and spread of the epidemic. At the same time, people's governments at all levels must put the compensation funds issued by the government into the hands of every farmer.

35. What measures have been announced by the Ministry of Agriculture to prevent and extinguish highly pathogenic avian influenza?

The Emergency Regulations on Major Animal Epidemic Situations and the Emergency Plan for Highly Pathogenic Avian Influenza formulated by the state have formulated strict measures and procedures for the prevention, control and eradication of highly pathogenic avian influenza. Including: epidemic report, epidemic diagnosis, isolation and blockade of epidemic areas, culling, disinfection, emergency immunization, emergency system, funding sources and guarantees, etc. Once an epidemic occurs, the state starts the emergency system, and the epidemic will be controlled and eliminated soon.

36. After the outbreak of suspected highly pathogenic avian influenza, can farmers handle it by themselves?

You can't. The state clearly stipulates that poultry and poultry products in epidemic areas must be culled and treated harmlessly under the supervision of supervising agencies for animal epidemic prevention. All items that may be contaminated must also be disinfected and treated harmlessly. In addition, the blockade of epidemic areas, environmental disinfection control and epidemic situation confirmation can only be organized and implemented by local governments and animal husbandry and veterinary administrative departments. Farmers slaughter at will, and if blood, feces and polluted water are not treated or improperly treated, it will cause serious environmental pollution and the spread of pathogens.

37. What are the conditions for collecting diseased materials for pathogen isolation?

Highly pathogenic avian influenza is an infectious disease. In order to prevent the spread of the disease, the pathogen isolation must be carried out in professional laboratories set up by the Ministry of Agriculture and laboratories with BSL-3 conditions. Virus isolation and proliferation in laboratories without strict protective conditions are easy to cause virus spread and infection of laboratory personnel.

38. How to report the epidemic situation of highly pathogenic avian influenza?

The reported epidemic situation was identified by the Ministry of Agriculture, and the pathogen was isolated, identified and confirmed by the National Avian Influenza Reference Laboratory designated by the Ministry of Agriculture, and it was announced in time.

39. What are the responsibilities for violating discipline and law?

Violation of discipline and law mainly includes violation of epidemic reporting and handling system, violation of funds and materials guarantee and use system, violation of market management regulations, and disruption of social order. According to the seriousness of the case, disciplinary actions such as informed criticism and warning will be given to the units violating discipline and law, and disciplinary actions such as warning, demotion, dismissal and expulsion will be given to the principal responsible persons and other responsible personnel according to law. If a crime is constituted, criminal responsibility shall be investigated according to law.

40. How can farmers in epidemic areas get compensation?

In the areas where the epidemic occurred, the state implemented the policy of economic compensation for farmers. Mainly in accordance with the relevant policies formulated by the state, the direct culling and verification of poultry and destroyed products are compensated.

4 1. Is avian influenza included in the "List of Diseases"? Are you sure this is an epidemic? Is it included in the compulsory immunization list?

A: Bird flu has been included in the list of diseases. The Ministry of Agriculture has listed highly pathogenic avian influenza as a class I animal epidemic disease in China. At present, China stipulates that sensitive poultry in threatened areas with highly pathogenic avian influenza should be given emergency compulsory immunization.

February 2004 1