EN
Experiments were carried out on 20 geese, aged 6 months, affected with mixed infection of Amidostomum anseris, Capillaria anatis and Heterakis gallinarum. Ten experimental geese were twice disinfested at 10-day intervals and vaccination of the geese with a prepared DERVAC vaccine was performed 7 days after the second disinfestation, four weeks before laying period. The presence af antibodies was determined by ELISA. Sera with an optical density greater than 0.2 were considered positive. Experiments were carried out on four groups of geese, each composed of five birds: group I - geese infected and vaccinated with DERVAC vaccine; group II - geese infected and vaccinated; group III - geese infected and unvaccinated; and group IV - geese infected and unvaccinated. Coproscopic examinations were carried out twice a week for the whole experimental period. Blood samples for anti-DDV seroconversion were collected before vaccination nad next at 3-week intervals after vaccination, until the 21-st week of the experiment. The results of the experiment showed that even symptomless nematode infection caused by Amidostomum anseris, Capilaria anatis and Heteraks gallinarum in vaccinated geese, with prevalence of Amidostomum anseris, induced significantly delayed antibody production. Antibody level in infected geese at the 40th week after infection was significantly lower than that in the dehelminthized birds; therefore., it is recommended to examine parasitologically reproduction flocks of geese before their vaccination against DD and to perform disinfestation if infection with nematodes is found.