Defecation by Anopheles arabiensis mosquitoes of host blood infected with live Trypanosoma congolense.

Female Anopheles arabiensis mosquitoes were experimentally fed on hamsters and BALB/c mice which were either clean or infected with Trypanosoma congolense. The mosquitoes readily fed on either animal. A blood repletion rate of 82.7% was recorded for mosquitoes feeding on hamsters. Seventy seven per cent of the replete mosquitoes continued to feed while at the same time defecating the host's blood in droplets, ejected in quick succession from the anus. Ninety five per cent of mosquitoes defecating blood while feeding on mice infected with T. congolense ejected live parasites along with the blood. Clean mice inoculated intraperitoneally with T. congolense via tail or defecated blood developed parasitaemia between the third and seventh day. This phenomenon could imply possible mechanical transmission of the parasites to the hosts being fed on by the mosquitoes.