An epidemic of limb paresis (polio?) among the chimpanzee population at Beni (Zare) in 1964, possibly transmitted by humans (Additional information to Pan Africa News 2(2), 1995)
Until recently, hygienic precautions to protect chimpanzees from infections by human contagious diseases were not usual among laboratory and field workers in Africa. Before the 1970s laboratory scientists were not very concerned because the apes were cheap and abundantly available in Africa. From 1950 to 1956 at the Institut Pasteur ar Kindia in Guinea, 296 chimpanzees were bought from natives and kept ar the institute under quite bad conditions until most of the m were shipped overseas. One hundred of them died, mostly in the rainy season from lung diseases that might have been transmitted by villagers en route or from the institute's caretakers. (Dr. Langlais, Director, pers. comm., and my observ., 1960, published 1966). At the Station de Capture at Epulu in the former Belgian Congo about 200 chimpanzees were captured for the American polio research programme of Dr. F. Stare where the native workers had no toilet facilities (my observ., 1960). They were then transported to the Laboratoire Mdical at Stanleyvville and kept under horrible conditions awaiting shipment to the USA. Remarkably few of them seem to have died, mainly from lung conditions in wet weather periods, but no figures were provided to me (Dr. Courteois & Mad. Osterrieth, pers. comm., and my observ., 1960, published?).
Given this carelessness among laboratory scientists at that time, it is not surprising that I took no hygienic precautions when I conducted my field work at Beni in the dry seasons of 1960 and 1963. The chimpanzees there regularly passed through and fed in a papaya plantation in numbers up to 48 at a time, while farm workers ploughed the soil every day during the apes' absence and may have frequently defecated along the chimp paths. All apes, however, appeared to be in perfect health. Only one individual, estimated more than 40 years old, suffered from the infirmities of old age (Kortlandt, 1962). In 1964, however, seven chimpanzees were seriously handicapped by a limb paresis (Film and video by Kortlandt & Trevor, 1964/86). I have wondered whether this epidemic was introduced by the workmen. When the film was shown to two neurologists, one thought that the disease might have been polio while the other disagreed and suggested that it looked like pesticide poisoning. Pesticides were at that time, however, onlly used in a coffee plantation where the apes never came. I still hope to receive more comments from neurologists who have experience with human patients of such diseases.
Since 1964 I have occasionally warned colleagues about the risk of introducing human diseases into wild-living ape populations. Little attention seems to have been given to these risks. Therefore remember that the net reproduction factor of the Gombe chimpanzees has been calculated at 0.65 (Teleki, Hunt and Pfifferling, 1976). This means that each following generation would number only two-thirds of the preceding one. Remember the flu-like epidemic at Mahale that killed at least eleven chimps. Look at the pictures of the seven victims at Beni: the video cassettes are wildly available. Furthermore, keep in mind the decimation of Amazonian Indians and some other peoples when Western contagious diseases arrived, etc.
The risk of disease transmission from apes and monkeys to humans should also be considered. During field work occasional stepping into faeces cannot be avoided. Cleaning shoes in a hygienic way is a problem. And there are other problems. Is it true that some viruses can penetrate through the rubber of surgical gloves? Some advice on such issues by a specialist may be useful. While the risks are small, the warnings provided by the Ebola epidemic should be heeded.
*Author's address: 88 Woodstock Road, Oxford OX2 7ND, England, U.K.
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