Parasitemia and Tissue Infection in Sheep Fed Toxoplasma gondii Oocysts

The distribution of Toxoplasma gondii in blood and other tissues of nine adult sheep experimentally infected with T. gondii oocysts was studied by inoculation of mice with ovine tissues. Parasitemia was detected in five sheep 6 to 11 days after inoculation (DAI) and lasting usually for 1 to 2 days. Toxoplasma gondii was isolated from numerous internal organs of five sheep killed between 7 and 28 DAI and from eight organs of a sheep killed 64 DAI. Of the three sheep killed 117, 118, and 119 DAI, T. gondii was isolated only from brain, heart, diaphragm, skeletal muscle, and intestine. Skeletal muscle was infected in all sheep. More mice became infected after inoculation with chronically infected tissues digested in 1% trypsin than undigested tissues. Results indicate that skeletal muscle and brain should be used for parasitological surveys in sheep.