I. Epidemiological characteristics and clinical manifestations
Chicken and duck poultry are the main pathogenic sources of avian influenza. Avian influenza virus exists in the respiratory tract, digestive tract and organ tissues of diseased birds. It survives for a long time under humid and cool conditions. It is mainly transmitted through the respiratory system, the secretion of poultry and the contact of feces. The incubation period of avian influenza is affected by virulence, viral quantity, resistance, nutritional status, stress and other factors, ranging from several hours to several days, the longest time being 21 days. Highly pathogenic avian influenza (HPAI) has a short incubation period, rapid onset and high mortality rate. It can occur in all seasons of the year. It occurs in winter and spring. It can infect birds. Chickens, ducks, geese and turkeys are the most common, and chickens and turkeys are the most susceptible to infection.
Highly pathogenic avian influenza has no specific clinical symptoms, which are characterized by sudden onset, high depression, sudden rise of body temperature, loss of appetite, neck contraction, lethargy, cyanosis, edema, dyspnea, sneezing, mouth opening breathing, eye swelling and tears, and neurological symptoms such as head and neck backward, convulsion, dyskinesia in some animals. Then there was death, with a mortality rate of more than 90% in a few days.
Two, prevention and control measures
1. strengthen feeding management
Strengthening feeding management is the precondition of preventing highly pathogenic avian influenza. Good feeding management can guarantee the best growth state and disease resistance of poultry. Aquaculture farms should be located far away from major traffic routes, residential areas, market and other animal production sites. It is strictly forbidden to introduce poultry and eggs from epidemic areas. Regular use of aldehydes, phenols, chlorine-containing disinfectants and alkaline oxidants disinfection, strict disinfection of the surrounding environment of the site, poultry houses, feeding utensils and other facilities, disinfectants used alternately. All-in and all-out feeding mode should be implemented. To prevent the contact between poultry and wild birds, * strictly prohibit the polyculture of chickens, waterfowls and pigs, and strengthen the monitoring of migratory birds. All poultry farms are managed in a closed way. No unrelated personnel are allowed to enter or visit the farm area. Staff members and their routine protective articles should be strictly disinfected in the entrance and exit areas.
2. regular immunization
Vaccination can effectively prevent the occurrence of highly pathogenic avian influenza. Reasonable immunization procedures should be formulated for immunization in poultry farms, for example. The general immunization procedures are as follows:
(1) Immunization of breeding and laying hens. Chickens were immunized with recombinant avian influenza-Newcastle disease vaccine (rLH5-6 strains) or H5N1 subtype avian influenza inactivated vaccine at 7-14 days of age; once more at 25 days of age; once again before delivery with H5N1 subtype avian influenza inactivated vaccine and once again, and then every six months with H5N1 subtype avian influenza based on the results of immune antibody detection. The inactivated influenza vaccine was immunized once.
(2) Immunization of commercial broilers. Chickens were immunized with recombinant avian influenza-Newcastle disease (AI-ND) live vaccine or H5N1 subtype inactivated vaccine at the age of 7-14 days. After 28 days of age, the chickens were immunized with AI-ND live vaccine once more.
For ducks, geese, pigeons, quails and other poultry immunization, can be based on feeding purposes, refer to the immune process of chickens immunization. When an outbreak occurs, all poultry in the threatened area should be immunized once according to the surveillance of poultry immune antibodies in the threatened area; poultry immunized in the last month may not be immunized.
3. kill poultry with epidemic diseases.
Highly pathogenic avian influenza (HPAI) has a high morbidity and mortality, and there is no effective treatment at present. If highly pathogenic avian influenza is diagnosed, epidemic prevention and treatment should be carried out in time, epidemic spots, epidemic areas and threatened areas should be delimited immediately, epidemic foci should be investigated, all poultry with a radius of 3000 meters around the epidemic site should be killed immediately, burned and buried deeply, pollutants should be treated harmlessly, and epidemic situation and sources of infection should be quickly extinguished. Closed disinfection should be carried out in the areas under control, circulation of poultry products should be strictly prohibited, and the spread of the epidemic situation should be strictly controlled. To minimize human contact with poultry, we should wear gloves, masks and isolation clothes to deal with sick poultry. The poultry farm should be thoroughly cleaned, cleaned and disinfected, and be vacant for more than three months.
4. strictly monitor and quarantine
Regular routine blood sampling tests were carried out on poultry, and the abnormalities were diagnosed and treated immediately. It is strictly forbidden to introduce species from areas where epidemics occur. Before introduction, poultry farms requiring introduction of poultry should be carefully investigated, and hygienic safety should be tested. After each index is qualified, introduction should be conducted. After the introduction of poultry, strict quarantine and isolation observation for more than 30 days, if no abnormalities can enter the field for mixed breeding. At the same time, reducing poultry feeding density can effectively reduce the incidence of avian influenza.