Haemorrhagic syndrome in cattle associated with Trypanosoma vivax infection.

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.