Reactivated and clinical Toxoplasma gondii infection in young lambs: Clinical, serological and pathological evidences

Abstract

In this study, fatal toxoplasmosis with severe neurological clinical signs was evaluated in 20 lambs of a sheep flock containing 90 Akkaraman sheep, 60 lambs and 3 rams. The clinical signs in infected lambs (n=20) included incoordination, head shaking, tremors, shaking up, difficulty walking and subsequent death. No incidence of abortion observed in pregnant ewes. Two lambs with severe clinical signs were euthanized and necropsied following clinical and hematological examinations. Blood samples were also collected from the mothers of dead lambs and rams for Sabin-Feldman dye test to detect Toxoplasma gondii-specific antibodies. T. gondii infection was further confirmed by PCR analysis using T. gondii B1 gene specific primers. The histopathological findings included non-purulent myositis with T. gondii-like tissue cysts in the heart and skeletal musculature, severe necrotic vasculitis and multifocal necroses in the brain, liver and lungs. T. gondii immunoreactivity was present in the lungs, liver and spleen as well as tissue cyst-like structures. In differential diagnosis, Neospora caninum infection was excluded by immunohistochemical and PCR analyses. According to current literature, there has been no previous report on clinical toxoplasmosis in newborn lambs or goat kids, and the number of reports on clinical toxoplasmosis in small ruminants is limited to two adult goats with fatality following systemic toxoplasmosis. Our study indicated that toxoplasmosis occurs in lambs with severe neurological signs and subsequent death.