HEMOLYTIC COMPLEMENT AND CLASS-SPECIFIC ANTIBODY-LEVELS IN GOATS DURING INFECTION WITH TRYPANOSOMA-EVANSI AND AFTER TREATMENT WITH DIMINAZENE ACETURATE

Following infection with Trypanosoma evansi, goats mounted a strong cl ass-specific antibody response, characterized by elevation of IgM and IgG antibody levels. Concomitant with the rising antibody levels and p arasitaemia, was a drop (P < 0.0001) in the total haemolytic complemen t. These changes were accompanied by pyrexia (> 39 degrees C), slight dyspnoea, and fall in haematocrit levels (P < 0.01), Clinical examinat ion revealed evidence of muscle wasting, lethargy and paleness of muco us membranes, Post-mortem examination carried out on one goat showed e nlargement of lymph nodes, spleen and liver and oedema of the lungs an d kidneys and a flabby heart. There was accumulation of sere-sanguineo us fluid in the peritoneal, thoracic and pleural cavities and petechia l haemorrhages on the serosa, pleura and intestinal mucosae. The brain was oedematous and showed evidence of congestion and meningeal petech iation. Cerebrospinal fluid (CSF) taken from infected goats did not sh ow changes suggestive of any central nervous system (CNS) invasion by the parasites. Following treatment with diminazene aceturate, and the disappearance of parasites from the blood, the haematocrit status and haemolytic complement levels recovered by the 4th week. There was a ra pid fall in the IgM-specific antibodies to near pre-infection levels. However, IgG-specific antibody levels were still elevated by the end o f the study. The study shows that infection with this parasite may sig nificantly affect goat production, because it causes changes which may lead to immunosuppression and organ failure. With the exception of Ig G class-specific antibodies, these changes are quickly reversed by che motherapeutic intervention, Levels of IgM and IgG class-specific antib odies may be a suitable indicator of the exposure status of goats to t his parasite because the former fall rapidly after treatment or cure, while the latter may persist for long periods.