The sheep (Ovis aries) as an experimental model for African trypanosomiasis. II. Biological study.

Sheep that have been experimentally infected with a strain of Trypanosoma brucei brucei reproduce the clinical symptomatology of human African trypanosomiasis. We measured two biochemical parameters which are altered during the infection; total serum and cerebrospinal fluid (CSF) proteins, and the time of appearance and levels of IgM in both serum and CSF. Serum protein levels were considerably raised (up to 90 gl-1), although in CSF the levels were always less than 1 gl-1. The ratio of serum albumin to globulins fell to a value of 0.40 during the course of the disease. Electrophoresis of CSF proteins demonstrated the appearance of polyclonal immunoglobulins. Plasma IgM levels rose to ten times normal values, and after the sixth week IgMs made up 10% of total CSF protein content. Specific antibodies were detected, by both indirect immunofluorescence and an ELISA technique, within two weeks after infection in the blood and after four weeks in the CSF.