Duck virus hepatitis

Def: is a highly fatal contagious disease of young ducklings, 1-28 days of age. Ducklings are most susceptible at the younger ages and gradually become more resistant as they grow older. The disease is rarely seen in ducklings over 4 weeks of age. The onset of the disease is very rapid, it spreads quickly through the flock and may cause up to 90% mortality. Sick ducklings develop spasmodic contractions of their legs and die within an hour in a typical "arched-backward" position. The liver is enlarged and shows hemorrhagic spots. To prevent this disease, keep age groups isolated and vaccinate breeder ducks with an attenuated live virus duck hepatitis vaccine (to produce maternally immune ducklings).

➡️Immunization of breeder ducks with:

-  Modified live virus vaccines, using DHAV, DAstV-1, and DAstV-2, provides parenteral immunity that effectively prevents high losses in young ducklings.

The DHAV-1 vaccine is administered SC in the neck to breeder ducks at 16, 20, and 24 weeks and every 12 weeks thereafter throughout the laying period.

Three immunizations are advisable for passive protection of ducklings.

-  An inactivated DHAV-1 vaccine for use in breeder ducks that have been previously primed with live DHAV-1 has been described. A single dose of the inactivated vaccine, administered IM before the birds come into lay, provides passive immunity for a complete laying cycle to progeny ducklings.

The chick-embryo origin, modified live DHAV-1 vaccine also can be used for early vaccination of ducklings susceptible to DHAV-1 (progeny of nonimmune breeders). This vaccine is administered SC or by foot web stab in a single dose to day-old ducklings. Vaccinated ducklings rapidly develop an active immunity within 3–4 days.

Antibody against DHAV-1, prepared from:

1- The eggs of hyperimmunized ducks and administered SC in the neck at the time of initial loss, is an effective flock treatment.

2- serum collected from adult ducks(age related disease)

Economic importance Significant economic losses may result from fatal outbreaks in commercial flocks and a drop in egg production.