| (Derzsy's disease, Goose parvovirus infection) Goose viral hepatitis is a highly contagious and fatal disease of domestic goslings characterized by tissue hemorrhages, liver lesions, ascites, hydropericardium, feather loss, and anorexia. It occurs worldwide except in the USA. Outbreaks have been reported in Muscovy ducklings, and the disease is economically important to both goose and Muscovy duck producers. Etiology:The disease can be reproduced by a goose parvovirus, although adenoviruses also have been isolated from affected goslings. The parvovirus, ~20-22 nm in diameter, is highly resistant and can only be propagated in susceptible goose and Muscovy duck embryos or cell cultures. Egg transmission occurs, resulting in hatchery infections. The disease is also transmitted by direct or indirect contact with infected birds. Clinical Findings:Experimentally, the incubation period is 4-7 days. Deaths usually occur at 9-14 days of age. During early stages of the disease, goslings manifest inappetence, thirst, crowding, conjunctivitis, nasal discharge, and diarrhea. Food and water are refused entirely before death. Mortality can be as high as 100% in goslings <1 wk old. In more chronic forms, the skin becomes reddened, the feathers are lost or become necrotic at their tips, and survivors become stunted. Age resistance is marked, and the disease is rare in goslings >4 wk old. In Muscovy ducks up to 12 wk old, sudden molt followed by stunting has been seen. Recovered birds are immune. Recovered females transfer maternal antibodies to the progeny through the egg yolk. Lesions:At necropsy, the most characteristic change is a swollen and occasionally firm liver with petechial hemorrhages on the surface. Other lesions include tissue hemorrhages in the spleen and pancreas, serofibrinous pericarditis, perihepatitis, and ascites. Diphtheritic and ulcerative lesions on the epithelial lining of the oral cavity, tongue, and pharynx are common. Histological lesions include focal hepatic and myocardial degeneration, necrosis, and hemorrhage. Heterophilic cell infiltrations, bile duct proliferations, and fatty infiltrations are seen in the liver. Intranuclear inclusions are present in hepatocytes and Kupffer's cells. Diagnosis:A presumptive diagnosis can be based on the characteristic clinical course, age incidence, and gross and histological lesions. Diagnosis is confirmed by isolation of the virus in susceptible goose or Muscovy duck embryos or cell cultures, neutralization of the virus by specific antiserum, and immunofluorescence of the virus in tissue cultures or tissue sections. Differential diagnoses include duck plague (which may infect geese or Muscovy ducks), adenovirus infections, avian influenza, and hemorrhagic nephritis and enteritis. Bacterial infections due to Pasteurella anatipestifer and Escherichia coli also should be considered. Prevention and Treatment:Strict isolation of goslings free of goose viral hepatitis during their first 4 wk prevents the disease. Immunization of breeder geese to increase maternal antibody levels of newly hatched goslings is indicated for flocks raised in endemic areas. The virus can be attenuated by multiple passages in goose or Muscovy duck embryo cell cultures for use as a breeder vaccine. Vaccination of breeder geese with duck-embryo-adapted virus vaccine provides good protection in progeny. Breeders should be vaccinated twice, 3-6 wk apart, at least 3 wk before the laying season. The vaccination should be repeated twice yearly to ensure adequate protection throughout the growing season. Intensively reared Muscovy ducklings exposed to goose viral hepatitis should be vaccinated at 3 wk of age. Hyperimmune or convalescent serum (1 mL) administered SC to day-old goslings is indicated to prevent or treat the disease in exposed flocks. |
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