Human serum sensitivities of Trypanozoon isolates from naturally infected hosts in the Luangwa Valley, Zambia.

Of 235 Trypanozoon stocks isolated from naturally infected hosts in northeastern Zambia and tested by the Blood Incubation Infectivity Test (BIIT), 176 came from man, 37 from wild-caught tsetse, 11 from wild animals and 11 from domestic livestock. Of those from man, 2 gave unexpected, human-serum-sensitive (HSS) reactions on first testing; all 15 stocks from tsetse in the northern area (Kampumbu) were strongly serum-resistant (HSR) while 22 other infections, from tsetse in the southern area (Kakumbi), gave 1 equivocal, 11 positive and 10 negative test responses. HSR Trypanozoon infections were found in a bushbuck, a warthog, in a giraffe (for the first time) and in a "sentinel" goat, used to monitor SS transmission in a small SS endemic village.