Acute Trypanosoma vivax infection of Ethiopian cattle in the apparent absence of tsetse.

Investigations of acute trypanosomiasis in a group of 1,200 cattle provided strong evidence for mechanical transmission by haematophagous flies other than tsetse. Although recently introduced cattle may have had previous contact with tsetse flies the incident occurred in an area remote from their known range. Mortality exceeded 6% before the outbreak was controlled by chemotherapy. Mechanically transmitted Trypanosoma vivax infection may be of widespread occurrence in eastern Ethiopia.