TRYPANOSOME INFECTIONS OF THE TSETSE-FLY GLOSSINA-PALLIDIPES IN THE LUANGWA VALLEY, ZAMBIA

Trypanosome infections of Glossina pallidipes were investigated at a s ite in the Luangwa Valley, Zambia between June 1991 and September 1992 . Almost 3700 flies were captured, dissected, screened for trypanosome infection, and aged using both wing fray and (for females) ovarian ca tegories. DNA probes were used to identify midgut infections. Prevalen ces of mature infections were 6.2% Trypanosoma vivax-type and 3.1% T. congolense-type (including low prevalances of T. brucei, T. simiae and another Nannomonas species). The prevalence of infection increased wi th age. For both types of infection this relationship could be describ ed by a simple 'catalytic' model which generates estimates of per capi ta rates of infection. Prevalences varied significantly with time inde pendently of any changes in the age structure of the tsetse population . This may reflect temporal variation in the per capita rates of infec tion.