Perinatal changes in lambs infected with Toxoplasma gondii.

Twenty-one lambs, born to ewes experimentally infected with Toxoplasma gondii during pregnancy, which were either stillborn or died soon after birth, were examined for pathological changes. In the brain perivascular cuffing by lymphoid cells and distinctive focal inflammation was widespread and common. In addition, focal leucoencephalomalacia, often associated with haemorrhages, was found in almost half the cases examined. The livers from 14 of the lambs displayed large accumulations of lymphoreticular cells in portal triads and foci of extramedullary haemopoietic cells were present in 10. Among other tissues examined the adrenal gland in 14 cases was infiltrated by eosinophils which were often associated with macrophages that contained pigment with the staining characteristics of lipofuscin. In bone marrow the myeloid-erythroid cell ratio was significantly less than that in control animals. It is concluded that intrauterine infection of the ovine fetus with T gondii causes characteristic neuropathological changes in the fetus and that anoxia due to cotyledonary damage plays a significant role in the cause of death.