Immunological aspects of Derzsy's disease in goslings.

Laying geese naturally infected by the parvovirus agent of Derzsy's disease transmit IgG type maternal immunoglobulins through the eggs to their offsprings. The passively acquired yolk antibodies persisted at a relatively high level until about 12-14 days of age, but were eliminated from the birds during the 3rd week of life. The IgG type immunoglobulins present in the specific hyperimmune sera used for preventive treatment have a half-life, about 6 days, and their blood level falls to a minimal value during the 2nd week following administration. The primary humoral immune response of geese to parvovirus is characterised by the production of initially IgM and then IgG type immunoglobulins. Gosling less than 20 days old began to produce antibodies later after antigenic stimulation and in lower titre than did older birds. The presence of passively acquired antibodies also interfered with the development of an active immune response. It follows that the most efficient approach to the protection of susceptible goslings against Derzsy's disease is to boost their levels of maternal antibodies through active immunisation of the laying flocks.