Duck viral hepatitis is an infectious disease caused by duck enteritis virus that is more likely to appear in the young duck population, with high case fatality rate, rapid spread, sudden onset of illness and other characteristics, which has seriously endangered the sustainable development of the current duck industry. Combined with years of work experience, this paper summarizes the diagnosis and prevention and control measures of duck viral hepatitis.
< h1 class="pgc-h-arrow-right" >1 pathogenic properties</h1>
Duck hepatitis virus belongs to the small RNA virus family, at present, it has been found at home and abroad that there are 3 serotypes, namely type III., type II., type I., of which type III. and type II. are enteroviruses of the family Microribonucleic Acid Virus, and Type I is the astrovirus, and type I is the most likely to appear. Duck hepatitis virus usually has strong resistance, can survive more than 37 days in the fecal and urinary environment, and can survive more than 70 days in the brooding room, but it can be killed by bleaching powder 2%, formalin 1%, sodium hydroxide 2%, etc. Duck hepatitis virus damages the liver of ducks, which in turn induces lesions of the blood circulation system, respiratory system, brain nervous system, etc., and finally dies due to liver failure.
Chicks under 5 weeks of age are the most likely, mostly ducks under 1 week old, the incidence of case fatality can be higher than 90%, and more than 5 weeks old will basically not die of the disease. Adult ducks have no obvious clinical symptoms even if they are infected, and they are prone to becoming poison carriers. Virus-contaminated utensils, soil, air, etc. can be used as a new source of infection for duck viral hepatitis. The disease has no seasonality, as long as there are insufficient biosecurity prevention and control measures, improper feeding management and other reasons can lead to the spread and development of duck viral hepatitis.
<h1 class="pgc-h-arrow-right" >2 Clinical symptoms and autopsy lesions</h1>
Viral hepatitis in ducks spreads faster and becomes more rapid, and once the infection of young ducks is often fatal within 4 days of illness. Sick chicks show sluggishness, listlessness, droopy wings, some will have general convulsions, and there will be obvious bruising at the tip of the claws and beak of the dead ducks. Autopsy of sick dead ducks found that the liver is the most important lesion location, the liver is fragile and swollen, there are several bleeding spots, bleeding spots on the surface of the liver, gallbladder swelling, kidney enlargement, and vascular congestion.
<h1 class="pgc-h-arrow-right" >3 diagnosis</h1>
3.1 Preliminary Diagnosis
Sluggish movement, listlessness, and drooping of duck wings are the main clinical features of duck viral hepatitis, and the preliminary diagnosis of duck viral hepatitis can be made by pathological autopsy of sick and dead ducks, age of onset and other factors.
3.2 Laboratory Diagnosis
Sterile collection of liver tissue from sick and dead ducks, fixed on a slide, stained by adding a certain amount of fluorescent antibodies dropwise, and then placed in a microscope for careful observation, if fluorescence is observed, it can be regarded as positive. At the same time, the diseased material is inoculated with duck embryos and chicken embryos, and the allantoic fluid of sick and dead ducks is collected for viral agglutination test.
Be careful to distinguish from paramyxovirus disease, avian influenza, aflatoxin poisoning, especially to distinguish between aflatoxin poisoning and duck viral hepatitis, although both can cause liver damage and other symptoms in chicks, but the former will not induce liver bleeding.
< h1 class="pgc-h-arrow-right" >4 prevention and control measures</h1>
4.1 Build a good breeding environment (1) Regularly use disinfectants to disinfect the entire breeding environment, and try to kill all pathogens in the breeding environment. (2) Strengthen the supervision of the epidemic situation, once a suspected diseased and dead duck is found, it is necessary to carry out harmless treatment in the first time to avoid the spread of the disease to the greatest extent. (3) In summer, it is necessary to check whether the water curtain and fan near the duck house are in normal working condition every day, and take cooling measures in time. In winter, on the basis of ensuring that the temperature in the duck house is suitable, it is necessary to ensure that the oxygen in the duck house is sufficient and the air quality is fresh.
<h1 class="pgc-h-arrow-right" >5 breeding healthy flocks of ducks</h1>
5.1 The management system for duck breeding must adhere to the principles of "all in, all out" and "self-propagation and self-rearing" to effectively enhance the quality of vaccination. In order to achieve an antibody pass rate for the entire duck farm, it is best to receive 2 duck viral hepatitis vaccines before the spawning of the breeding ducks.
5.2 In order to improve the resistance of the chicks to the environment, high-quality full-price chick feed should be selected, and an appropriate amount of compound electrolysis multi-dimensional, vitamins, etc. should be added.