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Parvovirus

Parvovirus. Dr. Chi-Young Wang. The strict age dependent; 100% mortality under 1o days of age but negligible in 4-5 wks old. In 2-3 wks, mortality below 10%. Old goose no symptoms. Especially for geese and Muscovy ducks. Vaccination of breeding stock has reduced the impact significantly.

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Parvovirus

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  1. Parvovirus Dr. Chi-Young Wang

  2. The strict age dependent; 100% mortality under 1o days of age but negligible in 4-5 wks old. • In 2-3 wks, mortality below 10%. • Old goose no symptoms. • Especially for geese and Muscovy ducks. • Vaccination of breeding stock has reduced the impact significantly.

  3. Susceptibility to Chemical and Physical Agent • Very resistant. • Stable at pH 3.0 for 1 hour at 37 ℃. • No loss of titers at 56 ℃ for 30 min.

  4. Laboratory Host System • Muscovy duck parvovirus is different from goose parvovirus. • Embryonated goose or Muscovy duck eggs. • Primary cells from these eggs. • An embryonic goose fibroblast cell lines (CGBQ).

  5. Mode of transmission • Excrete virus in feces and spread by direct and indirect contact (eat contaminated feed and water). • Vertical transmission (Egg transmission). • Old geese as carriers. • No biological vector

  6. Clinical signs (3-5 days for day-old; 5-10 days for 2-3 week-old) • Rapid with anorexia, prostration, and death occurs within 2-5 days: under 1wk. • Older birds with maternal antibody-protracted course. • Acute: anorexia, polydipsia, weakness, reluctant to move, nasal and ocular discharge, headshaking, and profuse white diarrhea, psedudomembrane covering tongue and oral cavity. Red swollen were founded in uropygial glands and eyelids.

  7. Clinical signs • Prolong disease: growth retardation, loss of down around the back and neck, ascites. • Penguin-like posture. • Poor management and secondary bacterial, fungal, or viral infections may influence the final mortality levels.

  8. Gross lesions • Acute: pale myocardium rounded at its apex. • Liver, spleen, and pancreas are swollen and congested. • A sero-fibrinous pericarditis, perihepatitis with straw-colored fluid in the abdomen, and hemorrhages in thigh and pectoral muscle (less frequent).

  9. Gross lesions • Pulmonary edema, liver dystrophy, and catarrhal enteritis. • Diptheritic and ulcerative lesions in the mouth, pharynx, and esophagus.

  10. Microscopic lesions • Degenerative changes in myocardial cells with loss of striation and fatty infiltration. The same changes in intestinal and smooth muscle cells. • Degeneration of hepatocytes with vacuolation and fatty infiltration. • Small, eosinophilic inclusion-like bodies were seen in cytoplasm of vacuolated hepatocytes. • Shrunken and necrotic acinar cells of pancrease.

  11. Immunity • Virus replication occurs in the intestinal wall and enters the blood stream. Virus reaches the liver and heart, where the most severe pathological changes occur.

  12. Immunity • Adult breeders transferred maternal antibody through egg yolks. A relatively high level of acquired antibody persists about 2 week of age. • Initial production of IgM and IgG. Viral neutralization (VN) tests or AGP was used to measure antibody up to 80 months.

  13. Diagnosis • Immunofluorescence or immunoperoxidase assay. • Agar gel diffusion technique of the allantoic fluid. • Inoculation of 10-15 day old embryonated geese or Muscovy duck eggs via the allantoic cavity. Embryo mortality occurs 5-10 days with hemorrhages and ochre-colored livers.

  14. Diagnosis • PCR for VP1 and 2 genes. • VN test in embryos or primary cell cultures and titer>1/16 considered positive. • Inoculation of cultures before they reach confluency. Syncytium formation and intranuclear inclusions are present in infected cells.

  15. Diagnosis • Electron microscopy. • ELISA or a blocking ELISA. • A plaque reduction assay. • Differential diagnosis: DVE (herpesvirus) with high mortality in geese and ducks of all ages.

  16. Intervention • Only egg from parvovirus-free flocks were put together and good hatchery hygiene. • Remove carrier by serological tests. • The first 4-5 weeks of life should be protected. • Hyperimmune serum in newly hatched goslings. But needs two doses of serum.

  17. Intervention • Active immunization of adult breeding geese and Muscovy ducks showed good protection via egg yolks. • Attenuation of virus in duck embryo cell cultures can be used. • Inactivated vaccines was effective.

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