Abstract
Trypanosomiasis is generally considered an exotic disease of tropical Africa and India. American trypanosomiasis (Chagas disease), which is caused by Trypanosoma cruzi, affects dogs, cats, armadillos, monkeys, and small wild animals.1-3,5 Trypanosoma cruzi, unlike its relatives, multiplies within the cytoplasm of the mammalian host’s cells. It has a predilection for cardiac and skeletal muscle where transformation to amastigotes, a form closely resembling Leishmania, occurs within the cells and the collections form pseudocysts. The vector is the reduviid or ‘kissing’ bug (Triatoma). Trypanosoma cruzi is known to be common in the triatomid bugs of south central Texas, and has caused chronic heart disease in dogs.4,6 It is not considered a risk to the human population, as the triatomid bugs' behavior does not favor transmission of the protozoans (the bugs do not tend to defecate in the vicinity of the bite wound).
Marsupials in South America have been intensively studied in relationship to triatomid/Trypanosoma life cycles.7 Most New World species appear to be highly resistant to pathologic disease, and function primarily as reservoirs of trypanosomes. Sugar gliders (Petaurus breviceps) appear to be peracutely affected and infection results in death. This may be the first report of Chagas disease in Old World marsupials.
Five sugar gliders and an African hedgehog (Atelerix albiventris) died over 1 mo. Most specimens showed little physical change or outward abnormalities. On postmortem examination, grossly enlarged and thickened myocardium and hyperemic lungs were common findings. Several sugar gliders had periocular swelling and hemorrhagic gastrointestinal contents. The most significant histologic lesion was a diffuse lymphoplasmacytic myocarditis with intralesional protozoa. Immunohistochemistry was negative for Toxoplasma gondii, Neospora sp., and Sarcocystis neurona. On thin sectioning, the protozoa were determined to have a distinct kinetoplast. Electron microscopic examination demonstrated the salient features of flagella (some in and some out of cytoplasm) and kinetoplasts supporting an identification of Trypanosoma sp.
Triatoma sp. bugs were found on the premises. The sugar gliders are fond of insects as a supplement to their diet and actively seek arthropods of many species in their nightly forays. It is suspected that Triatoma were not feeding on the gliders, but rather were themselves being eaten.
This is a known route of infection (often non-fatal and inducing a carrier state) in South American didelphid opossums.
Acknowledgments
Dr. Brad Barr and Mr. Robert Nordhausen provided invaluable assistance with additional testing.
Literature Cited
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