Experimental concomitant toxoplasma and malaria infection in rats.

The effect of concomitant toxoplasma and malaria infection on the reticuloendothelial system was investigated in rats. This was evaluated by the level of plasmodial parasitaemia; humoral antibody response; effect on splenic weight; histopathological changes in thymus and spleen; histopathological and histochemical changes in liver. The parasitaemia appeared after 2 days in single malaria and concomitant infections. The peak was reached after 6 days with single and precedent malaria, and after 10 days with precedent toxoplasma. The clearance of parasitaemia was delayed to 30 days with concomitant infections instead of 14 days with single malaria. Higher than normal malarial antibody levels were reached with precedent toxoplasma, while the toxoplasma antibodies were lower than normal in both concomitant infections. There was a significant increase in splenic weight in both precedent malaria and toxoplasma, followed by a decrease which did not return to normal in case of precedent malaria. The thymus was packed with thymocytes in precedent malaria, while depletion in the cortex occurred in precedent toxoplasma. In the liver, there was glycogen depletion and decrease in succinic dehydrogenase activity in both concomitant infections. Choline esterase activity in precedent malaria was decreased and returned to normal on day 40 while in precedent toxoplasma the activity was normal all through the period. The alkaline phosphatase activity was decreased and returned to normal on day 40 in both concomitant infections.