Death is stalking Africa’s cattle

Press, 4 July 1983, Page 20

Death is stalking Africa’s cattle

From “The Economist,” London

Africa’s cattle are being threatened by the recurrence of a virus that had almost disappeared from the continent in the 19605. Rinderpest is a form of diarrhoea that can be lethal. Before it burned itself out, an epidemic in the 1890 s wreaked such havoc among wild and domestic animals (more than five million cattle may 'nave been killed in southern Africa alone) that even the tsetse fly died out in some areas.

The animal protection and health division of the United Nations’ Food and Agricultural Organisation (F.A.0.) fears that something similar could happen now.

Over the last three years, increasing numbers of outbreaks of rinderpest have been reported. Worse, apparently fanning out from the Sudan, the disease is moving both west and south, to-

wards herds that may prove especially vulnerable to it. Ironically, some of today’s problems have arisen from an international financed, pan—African campaign mounted in 1962 to eradicate rinderpest. That involved large (and expensive) vaccination programmes, some of which were both free and compulsory.

On the face of it, the campaign was hugely successful. By the end of the decade, it seemed almost to have wiped out rinderpest among cattle. At the same time, the disease apparently disappeared from wildlife — for example, wildebeest and buffalo.

The consequences of the apparent success in suppressing rinderpest were two-fold. First, populations recovered: for example, there are an estimated 1.5 million-2 million wildebeest in the Serengeti game park now, compared to

260,000 in 1961. Second, governments allowed vaccination programmes to lapse. They seemed pointless when the disease was no longer an immediate threat. Anyway, they depended on a legacy of efficient colonial veterinary organisations, which were beginning to crumble. The trouble was that the disease had not been eradicated. Even at the height of the 1960 s campaign, immunisation programmes were not comprehensive — certainly not in the Sudan or Ethiopia. Pockets of the disease persisted. Now, with cattle vulnerable, rinderpest is again stalking Africa. Since the first outbreaks were reported in the Sudan three years ago, it has been confirmed to the north, in Egypt, to the west, in Nigeria and Chad, and as far south as Tanzania. Egypt may have got its outbreak under control; it started vaccinating fast once the disease was identified. Nigeria has been hit hard — the strain travelling west

seems to be particularly lethal Tens of thousands of cattle have died so far, and herdsmen are said to have stormed a veterinary institute in search of vaccine. The biggest worry is the strain travelling southwards. In Tanzania, its effects on cattle have beer relatively mild — though it is killing off buffalo. But East Africa’s zebu cattle are hardy beasts, which may well have developed some degree of genetic resistance to rinderpest. Farther south, in Zambia, Zimbabwe, Botswana, Namibia, Angola and South Africa, there are some 100 million cattle which have been largely free of the disease since the nineteenth century and which, therefore, have never been subject to large-scale vaccination programmes. They could prove much less resistant. Governments are unprepared for an epidemic. While South Africa has an emergency stock of rinderpest vaccine, most other countries have neither the vaccine nor the

means to administer it. The lack of stocks is probably not too serious: the vaccine is cheap and easy to produce. Administration is a problem. The equipment required — for example, refrigerators needed to keep the vaccine at a constant temperature — can be expensive. Organising an immunisation drive is hard when many herdsmen are nomadic. The F.A.O. — with help from the E. and the British Government — is mounting a campaign to stop the spread of the disease. Altogether $2 million has been spent so far on vaccine and equipment. Efforts are being concentrated on Tanzania, which has been given 2 million doses of vaccine. The F. ’s priority is to establish a buffer zone of vaccinated herds in the south of the country to prevent the disease from moving southwards.

A lot of money and speedy organisational effort will be needed if that is to be achieved in time. Nobody is sanguine. In the long term, the F.A.O. thinks that rinderpest can be eradicated. Some scientists disagree. The controversy centres on the question of whether the disease can be transmitted from wildlife to cattle.

One group of scientists holds that the mysterious disappearance of rinderpest from wild populations in the 1960 s is proof that the disease is effectively sustained by cattle. When they are immunised, the argument goes, the disease dies out. On that theory, the only obstacle to total eradication of rinderpest in Africa is an organisational one.

Others read the experience of the 1960 s differently. They hold that wild populations, kept down by continual outbreaks of rinderpest, were just too small in the 1960 s to sustain the virus. Now they are so large that rinderpest could travel through them like wildfire, infecting cattle all over the continent as it goes.

If that theory is correct, then rinderpest can never be eradicated by the vaccination of domestic cattle. Wild animals will act as a reservoir for the virus. It may be that this was true even in the 19605. Scientists now know that wild animals can be infected by a forin of the disease so mild that it normally goes undetected. Dr Paul Rossiter of the Kenyan Agricultural Research Institute points out that, in areas where rinderpest has not been reported, wild animals have been found to have antibodies specific to the disease. That means that they have been exposed. If such animals came into contact with, say, nomadic herds, the virus could then be passed along the chain to other domestic cattle.