The efficacy of heat-resistant Newcastle disease vaccine on village chickens in SocTrang province

摘要

Thermostable Newcastle disease vaccine (NAVETCO AVF/HR-NDV, 1-2 strain) was tested under field conditions in poor villages in Soctrang province, Vietnam. Twelve households were each provided with 30-50 one-day-old chicks which were reared traditionally. Eight vaccinated flocks contained a total of 320 chickens, and 4 control flocks contained 160 chickens. Vaccinated chickens received AVF/HR vaccine by eye drop at 5 days of age. They were revaccinated with the same vaccine supplied on cooked white rice at 14 and 35 days of age. Only about two-thirds of the chickens in each flock received vaccine; the others were exposed to the vaccinated chickens. At 7 weeks of age, 91% of the vaccinated chickens and 88% of the contact chickens had levels of haemagglutination-inhibition antibody indicative of protection against chal-lenge. Control chickens had developed no antibody. The vaccine was judged to be safe and efficacious. Subsequently, 20 training courses were organised involving 223 villages, which commenced vaccinating their flocks. Many families bene-fited from increased productivity from their flocks.