Sleeping sickness / by F. M. Sandwith.

  • Fleming Mant Sandwith
Date:
1912
Catalogue details

Licence: In copyright

Credit: Sleeping sickness / by F. M. Sandwith. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    bitten or pricked, there propagates and so gives rise to the disease.” The parasites conveyed by the flies, and found by Major Bruce to be present in the blood of every affected animal, are trypanosomes (Trypanosoma brucei), which can be seen under a powerful microscope as transparent, elongated bodies, pointed or somewhat blunt at one end, with a fine lash at the other, which is in constant whip-like motion. They can be seen quite distinctly, wriggling among the red blood corpuscles and causing much commotion. It was not known how the parasite caused the death of its host, but it was thought probable that it did so by the production or secretion of some poisonous substance. The tsetse flies which are the carriers of these parasites haunt certain very definitely prescribed areas, and, on entering these regions, the unfortunate travellers and animals are instantly attacked. “On entering the fly country,” writes Major Bruce, “one is not left long in ignor- ance of the presence of the tsetse. The natives may be seen slapping their naked legs, the dogs bite round, and the horses kick.” Unlike the mosquito, both sexes of the fly bite alike. It was evident to Major Bruce that the fly procured the parasite which caused the disease from some definite source, and European hunters and natives stated that wild game— buffalo, wildebeeste, water buck and koodoo—must be present where the disease was found. Where there was no game, they maintained, there was no nagana. Major Bruce therefore microscopically examined the blood of various species of wild game to see if he could find in it the minute trypanosomes which give rise to the disease. But the para- sites are not sufficiently frequent in the blood to be detected. He then injected the blood of such game, immediately after death, into healthy dogs, and some of these animals, though not in a fly country, subsequently showed the characteristic symptoms of nagana. He thus proved that several species of wild beasts, living in a fly country, harbour the nagana parasites, apparently without producing in them any great discomfort, though they may occasionally suffer from its effects and even die in consequence. The tsetse fly, carrying the infected blood of the wild
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