COCCIDIOIDOMYCOSIS

Coccidioidomycosis is a fungal disease caused by Coccidi- oides spp., dimorphic pathogenic fungi that cause infections characterized by respiratory, dermatological, musculoskeletal, neurological and ophthalmological signs.

Two genetically distinct species have been recently iden­tified: namely Coccidioides immitis and Coccidioides posa- dasii. These two species are ubiquitous in the endemic regions, where they grow as moulds on soil, producing arthroconidia.

They have different geographic distributions: C. immitis is found in California, whereas C. posadasii is found in Central and South America.

Coccidioides spp. is considered infectious for all mammals and at least some reptiles. However, infections by Coccidi- oides spp. have been reported in no avian or animal species in Europe. Primates are particularly susceptible, and dis­seminated coccidioidomycosis has been reported to cause death in many species. Coccidioidal infections have also been described in free-ranging wildlife, such as as western cougars (Puma concolor), coyotes (Canis latrans), bot­tlenose dolphins (Tursiops spp.) and California sea lions (Zalophus californianus)(^,∖

The most important risk factors for acquiring the infec­tion are dust exposure, pregnancy, age, sex and immuno­suppression. The infection occurs when dust-borne arthroconidia are inhaled. Upon inhalation, the fungi convert to spherules, which contain endospores that are released by rupture and lead to new endospore-producing spherules. Approximately 60% of incidents of exposure to the fungus result in subclinical infection. The clinical form of coccidioidomycosis is characterized by several signs that range from a primary (usually benign) pulmonary infec­tion, to a progressive pulmonary or extrapulmonary disease. Clinical signs include fever, lethargy, weight loss associated with anorexia, dullness, coughing and lameness. Diagnosis is based on the detection of endosporulating spherules in areas of lesion. Culture of specimens is recommended along with histopathological studies, although cultural examina­tion should be restricted to biosafety level 3 laboratories.