Toxoplasmosis broke out collectively on a breeding swine farm. There was a relationship between the stage of rearing of swine and the time of clinical manifestation or morbidity of the disease. Pigs weighing 45-120 kg showed a morbidity of 98% 1-4 days after the outbreak, pigs weighing 10-40kg 59% 4-5 days, adult pigs 57% 5-8 days, and suckling piglets 17% 15 days. On the whole farm 74 of 137 head (54%) showed clinical manifestations.
Infected animals were detected by taking body temperature and treated immediately with sulfamonomethoxine. As a result, they recovered 3-9 days later. Ten of eleven of them were negative for protozoa, suggesting the effect of early treatment with the agent.
Hemagglutination antibody against Toxoplasma increased remarkably in titer in all the swine, both clinically infected and not clinically infected, on the farm, indicating that no animals were exempt from infection. An antibody survey revealed that all the young born 1-2 months after the outbreak had been infected, but that those born 6-7 months after the outbreak were free from infection. The present outbreak may have been caused by oral infection with Toxoplasma oocysts.
