Coccidioidomycosis: What's old and what's new

Coccidioidomycosis was first described in Argentina >100 years ago. Since then, what was once seen as a disfiguring and often fatal illness is now recognized as having a wide range of manifestations, including asymptomatic infection with longlived immunity. Over the past decade, symptomatic illness has been reported with increasing frequency in the two major endemic regions in the US, Arizona and the San Joaquin Valley of California. Coccidioides now encompasses two species, C immitis and C posadasii, but the clinical implications of speciation remain unclear. Although Coccidioides appears to primarily reside in the soil, it is only infrequently isolated from environmental sites and its exact ecological niche is undefined. Coccidioidomycosis often presents with symptoms that are indistinguishable from bacterial communityacquired pneumonia. This has led to underdiagnosis even in the coccidioidal endemic regions. Management has been advanced by the availability of azole antifungals but many patients with primary pneumonia improve without therapy. Virulence factors observed in other microorganisms, such as melanin production and urease, have also been observed in Coccidioides. There has been a sustained effort to develop a vaccine for coccidioidomycosis but no one candidate has yet emerged. An attenuated strain of C posadasii holds promise.