Studies on the epizootiology of rinderpest in blue wildebeest and other game species of Northern Tanzania and Southern Kenya, 1965–7

Abstract

A serum neutralization test was used to determine the incidence of rinderpest antibodies in populations of blue wildebeest (Connochaetes taurinus albojubatusThomas) occurring in the Serengeti-Mara districts of N. Tanzania and S. Kenya. By correlating the age of animals at the time of shooting with the presence or absence of antibodies it was possible to outline the course of rinderpest in these animals over the period 1961–7.Serengeti migrant wildebeest were extensively infected in 1961, but not in 1962 or any subsequent year. No samples have been collected from this group since mid-1966. Kirawira resident wildebeest were last infected in 1961 according to samples collected in February 1967. Two of 13 animals born into the Mara resident population in late 1961 or early 1962 were found to possess antibodies, together with a high proportion (74%) of animals born in early 1961. This finding was considered indicative of a rinderpest epizootic in this group in the terminal weeks of 1961. No subsequent infection occurred in Mara wildebeest between 1962 and March 1966. Ngorongoro resident wildebeest were infected in the second half of 1962 but have remained free of rinderpest from 1963 until at least April 1966.The findings of the present survey were compared and contrasted with results of a similar study carried out some 2 to 3 years previously.Field strains of bovine rinderpest virus were isolated from the Loliondo district of N. Tanzania in November 1965 and March 1966. Serum samples from buffalo, eland, impala, warthog, and resident wildebeest which inhabited areas adjoining the two outbreaks failed to provide evidence of any recent epizootic in game animals. Circumstantial evidence indicated that the virus could have persisted in the Loliondo area since 1961. Two resident wildebeest born in 1963 and 1964 respectively, were thought to have been infected during a period when the disease went unrecognised. Serengeti migrant wildebeest were not found to have been infected after a period of potential contact with sick cattle in March 1966.