Fig. 1

Fungi belonging to the genus Coccidioides inhabit arid and semi-arid zones with alkaline soils and extreme temperatures. Under these conditions, they grow in a mycelial form and develop asexual reproductive structures. (1) These structures may be dispersed by the wind and find a host, primarily mammals, including humans, where dimorphic changes occur, giving rise to a parasitic form that has spherules and endospores. (2), Hundreds of endospores are released, and each endospore has the capacity to give rise to another spherule, repeating the life cycle in the host. In humans, the infection may progress to disease, or it may be eradicated by the immune system. Similarly, in animals, the infection may or may not lead to disease. In the case of disease and eventual death of the host, Coccidioides become exposed to the environment and return to a mycelial form (3), thus becoming integrated once again into their habitat