BLASTOMYCOSES
Blastomycosis is one of the principal systemic mycoses, caused by a dimorphic fungus, Blastomyces dermatitidis, which grows as a ‘mycelial’ form at room temperature and as a ‘yeast’ form at 37° C.
The mycelial form grows in sandy, acidic soils and along waterways. Blastomycosis is endemic in North America but has been described in circumscribed African regions and sporadically reported in European human patients. The disease has been described in dogs, and occasionally in wild animals (i.e. wolves and lions)1-3’4). Mammals become infected by inhaling conidia. At 37°C in the host, conidial spores transform into yeastphase cells, which multiply within the lung and may disseminate via the bloodstream and lymphatic system to visceral organs.Canine blastomycosis is characterized by chronic cough, dyspnoea, weakness, lethargy, lameness, anorexia, weight loss, nasal and ocular discharge and cutaneous lesions. The infection is diagnosed by fungal culture, which should be restricted to biosafety level 3 laboratories. Enzyme-linked immunosorbent assay (ELISA) serology techniques are also available. At necropsy, in wild animals it is possible to observe many firm nodules up to 2.0 cm in diameter in the lungs, which histologically correspond to focal concentrations of macrophages and yeast-like round cells with a thin wall.