Toxoplasmosis in captive Bennett's wallabies (Macropus rufogriseus) in Argentina.

Wallabies and other Australian marsupials are among the most susceptible species to Toxoplasma gondii. Fatal generalized toxoplasmosis was diagnosed in two captive 3 year-old female Bennett's wallabies (Macropus rufogriseus) from Argentina (w 1 and w 2) with a history of sudden death. Both animals had internal joeys which died 2 days after their mothers. Serologically, both females and one adult male without clinical signs from the same enclosure (w 3) had antibody titers for T. gondii>or=800 by the modified agglutination test (MAT); another adult male (w 4) was negative (MAT titer<25). Microscopically, tachyzoites were observed associated to non-suppurative meningoencephalitis, hepatitis, myositis, myocarditis and severe enteritis in hematoxylin and eosin stained sections from both w 1 and w 2. Immunohistochemically, parasites in heart, brain and liver sections of both female wallabies reacted with T. gondii antiserum. T. gondii was isolated from brain tissues of w 1 and w 2 by bioassay in mice and by culture in bovine monocytes and both isolates were cryopreserved. Genomic DNA was isolated from tachyzoites grown in cultures derived from both animals. The primer pair B22/B23 specific for T. gondii produced 115bp amplicons on poliacrylamide electrophoretic gels. Stray cats were suspected as the possible source of infection. Not all infected macropods were ill, showing that the infection may be asymptomatic and is not always fatal. A vertical infection could not be proved in the joey from w 2. As far as we know, this is the first confirmed report of toxoplasmosis in Bennet's wallabies in Argentina.