Adiaspiromycosis in suspected cases of pulmonary tuberculosis in the common brushtail possum Trichosurus vulpecula)

Abstract

Pulmonary adiaspiromycosis was diagnosed in 15 of 17 common brushtail possums (Trichosurus vulpecula) examined for bovine tuberculosis. Emmonsia crescens was isolated from two of the affected animals. This is the first reported isolation of this dimorphic fungus in New Zealand. The infections varied from light to heavy with sparsely distributed, focal, 1–2 mm diameter, grey-white spherical granulomas in the lightly infected cases to innumerable foci throughout the lungs in the heavily infected cases. Histologically, the lesions were characterised by a central fungal adiaspore consistent in morphology with E. crescens located in alveolar spaces or bronchioles. These were surrounded by a cuff of granulomatous inflammation which varied in density and extent in proportion to the degree of degeneration exhibited by the organism.

The lesions in most cases of adiaspiromycosis in the possum are sufficiently distinctive to allow their differentiation from tuberculosis by gross examination, but where any doubt exists over the possibility of dual infection by Emmonsia and Mycobacterium species differentiation should be made on the basis of a histological examination of the tissue and culture for mycobacterial organisms.