Toxoplasmosis in Sheep: Epidemiological Studies in Flocks with Reproductive Loss from Toxoplasmosis

The epidemiology of toxoplasmosis was studied in 51 flocks with reproductive loss from the infection. Overt toxoplasmosis was diagnosed on 2–4 neighbouring farms on 6 occasions, involving a total of 15 flocks. In 14 of the 51 flocks the frequency of abortion was highest in a definite part or age group of the flock.Evidence was found that the source of infection may be confined to a particular part of an area or of a farm. There was apparently no transmission of Toxoplasma gondii from sheep with overt or latent toxoplasmosis to susceptible sheep. There were good reasons to believe that the parasite might have been transmitted via the silage in 1 of the flocks.