Toxoplasma sp. Scanning electron micrograph (SEM) of Toxoplasma sp. Toxoplasma is a genus of crescent-shaped sporozoans that parasitize cells in birds and mammals, and complete their life- cycle in a single host. Toxoplasma gondii infects sheep, cattle, dogs and man, sometimes provoking an acute illness, toxoplasmosis. Infection in man occurs through undercooked meat, contaminated soil, or by direct contact. Symptoms are usually mild, but severe infection of lymph nodes may occur. In pregnant women, infection may affect the foetus. Severe cases are treated with sulphonamide drugs. Magnification: x17,600 at 8x6 inch size.