The status of Newcastle disease and the use of V4 vaccine in Malawi.

Data on the incidence of Newcastle disease in Malawi obtained from various sources including serological surveys, questionnaires and interviews, as well as statistics on laboratory-confirmed cases, showed the disease to be widespread throughout the country. Chickens vaccinated with La Sota and Komarov vaccine strains were often inadequately protected against the disease, especially those under smallholder management. Trials involving laboratory chickens and chickens under both intensive and smallholder management showed that V4 vaccine, given by eye-drop, drinking water and oral droplet methods, induced an antibody response sufficient to protect birds against challenge with virulent field isolates of Newcastle disease virus. V4 is recommended as an alternative to La Sota and Komarov vaccines, particularly for smallholder flocks, because of its thermostability, its ease of administration and its transmissibility. Large scale use of V4 appears to have reduced the incidence of Newcastle disease in rural parts of Malawi.