Notes on Some Parasites from Chimpanzees.

Through the kindness of Dr. H. C. Bingham and Professor R. M. Yerkes an opportunity was presented to examine for parasites 4 chimpanzees maintained by the Institute of Psychology at Yale University. These animals came from various parts of Africa and have been at the laboratory of the Institute since September 12, 1925, before which time 2 of them were for 3 months in a zoo in Philadelphia.

Since March, 1926, occasional samples of stools from the chimpanzees have been examined, always with the result of finding in large numbers motile forms of a Balantidium morphologically indistinguishable from Bal. coli. Cysts occurred only very rarely. Although these ciliates have swarmed in the intestines of the animals, at least since examinations first began, and have been passed in great numbers, presumably in every stool, the chimpanzees are healthy and show no visible signs of suffering from their infection. The stools have been more often soft than well formed, and have occasionally been diarrhoeic, but consistency has varied with the animals’ diet. In stools kept at room temperature the ciliates have remained alive for several hours, some as long as 32 hours after leaving the host.

Balantidia in anthropoids have been studied by Brooks, 1 Noc, 2 Brumpt, 3 Joyeaux, 4 Christeller, 5 Hegner and Holmes, 6 Ziemann 7 and Cunha and Muniz. 8 As a result of their observations it appears that the ciliates may parasitize orangutans, macaques, capuchins, baboons and chimpanzees; and that the animals are in most cases carriers, not apparently suffering from the presence of the parasites, but may in some cases develop ulcerative dysentery. Dobell and O'Connor state that these animals react to Balantidium in much the same way as does man and Hegner 9 says “it has long been known that the organism is pathogenic to primates.” Most of the authors have supposed that the species with which they dealt was Bal. coli.