Coccidioides

The fungus lives in arid soil as a mould with arthroconidia that become airborne after dust storms, earthquakes, or construction; inhalation is the sole route, with no person-to-person spread. In the lung at body temperature it converts to a thick-walled spherule filled with endospores, a morphology unique among the endemic mycoses, unlike Histoplasma's intracellular yeast within macrophages or Blastomyces' broad-based budding yeast. Endemic regions are the San Joaquin Valley of California, Arizona, and parts of New Mexico, Texas, and Central and South America. Most infections are asymptomatic or a self-limited pneumonia; characteristic accompaniments are erythema nodosum and erythema multiforme with arthralgia, the so-called desert rheumatism or valley fever complex, which paradoxically indicates a robust immune response and a good prognosis. Dissemination to skin, bone, and meninges is markedly more common in pregnancy, especially the third trimester, and in patients of Filipino and African descent and the immunosuppressed. Fluconazole is used for symptomatic and disseminated disease, with lifelong therapy for meningitis; amphotericin B is reserved for severe cases.