Experimental toxoplasmic myocarditis and myositis in mice.

Myocardial lesions were found in 71 per cent of mice infected with a highly virulent strain of These were maximal in the terminal stages of the infection. They were also found in 79 per cent of mice infected with a non-fatal strain and these were maximal on the 17th day. Changes in the skeletal muscle were found in 44 per cent of mice infected with the less virulent strain. They were maximal on the 31st day. The histological appearances are described and discussed. Reports of myocarditis and myositis associated with infections in man are reviewed and diagnostic criteria are assessed. A plea is made for an increased awareness of these 2 manifestations in cases of toxoplasmosis.