Trypanosoma vivax isolated from dairy cattle undergoing a haemorrhagic disease was inoculated into Ayrshire steers. Five of six infected animals experienced brief periods of diarrhoea and sublingual and gastro-intestinal haemorrhage. Gastro-intestinal bleeding coincided with markedly reduced numbers of thrombocytes and a high level of parasitaemia in the peripheral blood. Prothrombin times were extended and fibrinogen levels were elevated in infected animals. Plasma paracoagulation tests were positive for the presence of fibrin monomers and/or clottable early fibrin degradation products during the course of infection.

Twenty Kenyan patients with visceral leishmaniasis were evaluated for the presence of Leishmania donovani in their peripheral blood. Smears, cultures and hamster inoculations detected parasitaemia in 11, 10 and six patients, respectively, and at least one method detected parasitaemia in 15 patients (75%). The likelihood of detecting parasitaemia correlated with the density of parasites in splenic aspirate smears. It is apparent that parasitaemia with L. donovani occurs frequently in Kenyan patients with visceral leishmaniasis.