The co-administration of live fowlpox and Newcastle disease vaccines by non-invasive routes to chickens reared by smallholders in Tanzania and Nepal.

Abstract

The co-administration of commercial live fowlpox (FP) and Newcastle disease (ND) vaccines when given by non-invasive (needle-free) routes was demonstrated to be safe and to elicit immunity in two field studies, one in Tanzania the other in Nepal. Both studies were of a cluster-randomised controlled design in which birds were randomly assigned to one of five treatment groups: (i) administration with FP vaccine alone (feather follicle), (ii) administration with ND vaccine alone (eye-drop), (iii) concurrent administration of FP (feather follicle) and ND (eye-drop) vaccines, (iv) concurrent administration of FP (wing-web) and ND (eye-drop) vaccines, and (v) unvaccinated, acting as environmental sentinels. Data from a total of 1167 birds from seven villages in Hanang District of Tanzania together with 1037 birds from eleven villages in Dhading District of Nepal were collected over a period of 21 and 28 days, respectively. Immune responses to FP vaccination were evaluated by local take reactions while those to ND vaccination were evaluated serologically by haemagglutination inhibition test. Both studies demonstrated that the concurrent vaccination of free-range, indigenous breeds of chickens with live FP and ND vaccines, both administered by non-invasive routes, was safe and induced levels of immunity against FP and ND that were non-inferior to the administration of FP and ND vaccines alone. These findings are important to appropriately trained small-scale backyard poultry farmers as well as to paraprofessionals and community health workers helping to increase vaccine uptake and the control of both FP and ND in low- to middle-income countries.

Safety and Immunogenicity of ND Vaccines Used in Nepal

“…An earlier study from Nepal showed that LaSota strain vaccination in village chickens is immunogenic and efficacious against NDV infection [21]. A recent study also showed that LaSota vaccination was safe and induced a protective level of antibodies in 98% of vaccinated birds at 28 days post-vaccination [22]. Field verification study of ND I-2 vaccine also showed that it can induce protective levels of antibodies in 50-100% of birds at different study locations [23].…”