Toxoplasmosis in a Woodchuck (Marmota Monax) and Two American Red Squirrels (Tamiasciurus Hudsonicus)

Abstract

Toxoplasmosis was diagnosed in a woodchuck ( Marmota monax) and 2 American red squirrels ( Tamiasciurus hudsonicus). The woodchuck was euthanized by a wildlife rescue organization in New York after progressive clinical signs of head tilt, circling, and rapid weight loss. Necropsy examination revealed acute subdural hemorrhage over the right cerebral hemisphere. Histologic lesions included meningoencephalitis, myocarditis, and hepatitis. Protozoal cysts were present in affected and unaffected neuroparenchyma. The squirrels were found dead, emaciated, and moderately infested with fleas near a park in northern Indiana. In both squirrels, the lungs were consolidated with numerous nodules up to 2 mm in diameter. Histologically, pneumonia and encephalitis were associated with intracellular and free protozoa. Additional histologic lesions included multifocal lymphoplasmacytic encephalitis with intralesional protozoa in both squirrels. The protozoa were positive with Toxoplasma gondii-specific immunohistochemistry and had ultrastructural features consistent with T. gondii in both squirrels. A real-time polymerase chain reaction test using T. gondii–specific probes demonstrated protozoal DNA in the lung, brain, and kidney of the squirrels and in the brain and heart of the woodchuck. To the authors' knowledge, this is the first report of toxoplasmosis in woodchucks or American red squirrels. Because rodents are common near urban settlements, this finding underscores their role as important intermediate hosts for T. gondii.