Lesions of toxoplasmosis in Australian marsupials

Abstract

This report describes toxoplasmosis lesions in Australian marsupials. Clinical signs, necropsy findings and histopathological changes are summarized for 43 macropods, two common wombats, two koalas, six possums, 15 dasyurids, two numbats, eight bandicoots and one bilby. Animals either died suddenly without clinical signs or exhibited signs associated with respiratory, neurological or enteric disease. At necropsy, many marsupials had no visible lesions. Where present, common necropsy findings included pulmonary congestion, oedema and consolidation, adrenal enlargement and reddening, haemorrhage and ulceration of stomach and small intestine, and lymphadenomegaly and splenomegaly. Microscopically, affected lungs showed interstitial pneumonia and macrophage accumulation. Myocardial, skeletal and smooth muscle necrosis and neutrophilic inflammation were common. Organs had focal necrosis and/or fibrosis and lymphoid infiltrates. Toxoplasma gondii tissue cysts were common in muscle and nervous tissue. Free tachyzoites were commonly present in areas of necrosis. Selected sections from four macropods, two koalas, two dasyurids, one wombat and one possum stained specifically with avidin-biotin complex and anti-Toxoplasma gondii serum.