Experimental infection of cattle with Trypanosoma brucei rhodesiense

Infection of cattle with various stocks of Trypanosoma brucei rhodesiense indicated that 49% developed a fatal CNS disease comparable to that found in man. Duration of disease ranged from 85 to 1613 days post infection. All eight stocks of T. b. rhodesiense tested, including those from Ethiopia and Tanzania, induced CNS disease. Blood became positive three to five days after inoculation, and after an initial peak of parasitaemia remained positive for three to five months. Subinoculation of blood into rodents subsequently became negative, although trypanosomes persisted in the lymph nodes for at least 56 to 1613 days. Only animals with CNS disease had detectable parasites in the CSF, usually after the animals had undergone severe deterioration. At post mortem examination trypanosomes could usually be found in the lymph nodes and CSF, and occasionally in the blood. Clinical signs included fever, hyperkinesia, weight loss, cerebellar ataxia, tremor, salivation and hyperaesthesia. A mild to moderate anaemia accompanied a transient thrombocytopenia and leucopenia. Animals subsequently developed leucocytosis. A pleocytosis and elevated total protein in the CSF was found, which persisted in some animals for long periods. Histopathological examination of the brain showed prominent generalized perivascular infiltrates consisting mainly of lymphocytes and plasma cells. Mott's cells were regularly observed. Vascular changes were characterized by swollen endothelium, infiltration of the vascular wall by inflammatory cells, and in some instances perivascular oedema. In the most severe cases evidence of ischaemia consisted of large numbers of astrocytes, rarefaction of the parenchyma, and areas of necrosis with loss of normal architecture. Demyelination was limited to perivascular areas. Occasionally a moderate to severe pancarditis was found.