Outbreaks of rinderpest used to occur annually in cattle and wildlife in Northern Tanzania and Southern Kenya up until 1962 with the last recorded clinical outbreak in the area being in 1967. However in 1982 the disease was once again diagnosed on clinical and pathological grounds in buffalo and cattle at several widely separated localities in the north of the country. An intensive vaccination programme was started and the clinical disease disappeared once more, but the question remained was it possible for the wildlife and/or ‘shoat’ population to act as a reservoir of infection. After a couple of years research we found evidence that buffalo in the North and West of the Serengeti National Park had been continually exposed to the disease since 1982, whilst seropositive sheep and goats were found widely distributed in the north of Tanzania, especially in Simanjiro in Kitete District and Babati, Musoma and Tarime districts.
Cattle have been vaccinated in northern Tanzania annually for many years but the intensity of vaccination has been increased considerably since the 1982 outbreak. Between 1985 and 1988 a country-wide cattle vaccination programme was carried out and the immune status of the notional herd monitored. It is known therefore that the possibilities of transmission of infection between wildlife, small ruminants and cattle have been greatly reduced. Consequently the virus must be cycling separately within each population of domestic smell ruminants and buffalo. It must be assumed that this will continue unless there is intervention with vaccination of small ruminants. This, however, will not result in eradication of the virus if it continues to cycle in wildlife.
In summary, at present there is little, if any, reported clinical rinderpest in Tanzania, but the likelihood of the subclinical condition once more rearing its ugly head, particularly if the level of vaccination fa1ls, should not be underestimated.
Mr MARK JAGO is a Veterinary Surgeon who spent two years from 1987 to 1989 on a project jointly organised by the Serengeti Wildlife Research Institute and the European Community looking at the epidemiology of rinderpest in the wildlife and sheep and goat populations of Tanzania.