Abstract : This program sought to develop an effective, practical vaccine against African trypanosomiasis, useful to both military and civilian agencies. Related benefits include acquisition of knowledge pertaining to trypanosome immunity, host response and pathology of infection. Experiments conducted at WRAIR and in Kenya have demonstrated that experimental animals can be successfully immunized with irradiated trypanosomes. Rodents, cattle and monkeys can be rendered completely resistant to a challenging infection of T. rhodesiense. Partial immunity has been achieved against T. congolense. Continuing studies in Lambwe Valley, Western Kenya, show that 18 of 31 and 21 of 29 isolates from humans over a 7-year period are neutralized by two antisera, respectively. Five of 27 isolates from bovines also were neutralized by one antiserum. This indicates that stability of antigenic types has persisted throughout this period and that cattle are a reservoir host in the valley. Complete resistence to T. congolense has been achieved by repeated infection and cure. This immunity appears to be maintained after both syringe and tsetse fly challenge.

In a series of experiments involving 21 groups of mice, between 50 and 100 per cent of those inoculated with irradiated Trypanosoma congolense were completely protected from challenge inoculations of unirradiated T. congolense. Of 37 mice given a second or third challenge after 9 and 26 weeks, 23 remained parasite-free. Unimmunized control mice invariably developed parasitemias and most of them died as a result of the infection. Dogs and cattle failed to withstand challenge inoculations after they were treated with irradiated trypanosomes, though prepatency in these animals was longer than that of the controls.

Journal Article Immunization of cattle with X-irradiated African trypanosomes Get access R.E. Duxbury, R.E. Duxbury Search for other works by this author on: Oxford Academic PubMed Google Scholar E.H. Sadun, E.H. Sadun Search for other works by this author on: Oxford Academic PubMed Google Scholar B.T. Wellde, B.T. Wellde Search for other works by this author on: Oxford Academic PubMed Google Scholar J.S. Anderson, J.S. Anderson Search for other works by this author on: Oxford Academic PubMed Google Scholar I.E. Muriithi I.E. Muriithi Search for other works by this author on: Oxford Academic PubMed Google Scholar Transactions of The Royal Society of Tropical Medicine and Hygiene, Volume 66, Issue 2, 1972, Pages 349–350, https://doi.org/10.1016/0035-9203(72)90237-4 Published: 01 January 1972