Enzootic paracoccidioidomycosis in armadillos (Dasypus novemcinctus) in Pará State, Brazil

Abstract

In spite of an extensive literature on paracoccidioidomycosis, hardly anything is known about the ecology of Paracoccidioides brasiliensis in nature. During 1983, 152 wild animals of 21 species "were examined in a survey designed to detect sylvatic hosts of Leishmania near Tucuruí, a region of tropical rainforest with acid soils, in the State of Pará, northern Brazil. Hamsters inoculated with saline suspensions of liver and spleen from 4 out of 20 Dasypus novemcinctus developed generalized systemic infections after 4 to 13 months, with abundant spherical parasitic structures up to 30 mm indiameter, visible in unstained tissue smears. Inoculation of this material into fresh hamsters, produced lethal infections in within 1½ to 5 months, with gross pathological changes in the viscera and abundant parasites characteristic of P. brasiliensis in stained histological sections. Material from infected tissue grew slowly in Sabouraud Dextrose Agar, forming light-coloured cerebriform colonies approximately 1,5 cm in diameter after 2 months at 22-26ºC. Culture material was inoculated intradermally, intraperitoneally and intratesticularly into hamsters, laboratory mice and guinea pigs. Generalized infections were detected after approximately 5 months in female hamsters that had been inoculated intradermally. The fungus was re-isolated in culture from the infected hamsters. Parasites were detected in histological sections of the liver and spleen of the original armadillos, but no gross signs of disease. were noted in these animals. D. novemcinctus is widely distributed in the Neotropical Region but is absent from certain regions, such as Chile and Patagonia, where paracoccidioidomycosis is unknown. The fossorial habits of this armadillo may be relevant in the light of previous suggestions that the saprophytic phase of P. brasiliensis inhabits a subterranean environment. It is suggested that D. novemcinctus may play a part in the ecology of P. brasiliensis in nature.