On Trypanosoma brucei, T. rhodesiense and T. gambiense and their Ability to Infect Man

Abstract

1. A strain of T. rhodesiense, isolated from man and readily transmissible by tsetse, was passed by direct inoculation through a series of fourteen guineapigs over a period of 18 months. At the end of that time it had lost its transmissibility by Glossina palpalis, and it also failed to infect a volunteer.2. Another line of the same strain, after 98 days in a bushbuck, 30 days in a fowl and 294 days in oxen, proved still readily transmissible by G. palpalis and also readily infective to man.3. A second strain underwent seven consecutive cyclical passages through tsetse, then two passages by the syringe, and finally another cyclical passage, all save one in monkeys. When tested on man at the tenth and eleventh passages it was found to be non-infective.4. A strain of T. gambiense, isolated in November 1920 from a patient from Fernando Po, was found in February 1934 to be readily infective to man. The strain was entirely non-transmissible by and almost completely non-infective to G. palpalis.5. Three strains of T. brucei, one from the west, one from the north and one from the south of Uganda Protectorate, were found to be incapable of infecting normal healthy man. All the tests were carried out with cyclically infected tsetse.6. A freshly isolated strain of T. gambiense from a Uganda native was transmitted to man by cyclically infected laboratory-bred G. palpalis.7. A strain of T. rhodesiense, shortly after its recovery from a native of Tanganyika Territory, underwent three successive cyclical passages by laboratory-bred G. palpalis from monkey to monkey; at each passage the strain was tested on man and found to be readily infective.8. A strain from Nigeria showing points of resemblance to both T. gambiense and T. rhodesiense was found to be pathogenic to man, on subcutaneous inoculation of infected blood, three years after its first isolation.