Valley fever.

What it is

Valley Fever is a lung infection caused by Coccidioides — a fungus that lives in the dry, dusty soils of the American Southwest and parts of Central and South America. People become infected by breathing in fungal spores stirred up from the soil. Construction, agriculture, archeology, and even backyard digging are common exposure scenarios. Dust storms spread spores over wide distances. Most infections (~60%) are asymptomatic. About 40% cause a flu-like illness lasting weeks. A small percentage cause severe pulmonary disease, and ~1% become disseminated coccidioidomycosis — spread of the fungus to skin, bones, joints, or central nervous system — which can be life-threatening.

How it shows up", body: "The acute illness mimics community-acquired pneumonia: fever, cough, fatigue, headache, shortness of breath, sometimes a rash. It develops 1–3 weeks after exposure. Most patients are misdiagnosed as having bacterial pneumonia or simply "a virus" and treated empirically with antibiotics that don't work — until someone thinks to test for the fungus. Skin manifestations (erythema nodosum or erythema multiforme) are common and a useful diagnostic clue. Chronic pulmonary disease can develop — lung cavities, nodules, scarring — and these often resemble tuberculosis or lung cancer on imaging.

How we diagnose it

Suspicion in patients with pneumonia who live in or recently traveled to endemic areas is the first step. Diagnosis is made with coccidioidal serology (antibody testing) — usually positive 2–6 weeks after infection. Culture of sputum or tissue can confirm. Skin testing is available but used mostly for epidemiology.

How we treat it

Many cases of uncomplicated acute pulmonary disease resolve on their own and require only monitoring. More severe disease (high fungal burden, persistent symptoms, disseminated disease, or immunocompromised patients) needs antifungal therapy with fluconazole (most common) or, for severe disease, amphotericin B or itraconazole. Treatment duration ranges from 3–6 months for uncomplicated disease to lifelong suppression for meningitis.

What you can do

• —If you've been digging or working in dusty environments in the Southwest and develop a flu-like illness or pneumonia that doesn't improve, mention Valley Fever to your provider. The test won't be ordered if no one asks for it.
• —Wear a mask in dust storms or when doing dusty outdoor work in endemic areas.
• —If you have a weakened immune system, be especially cautious about dust exposure.
• —If you live in Arizona and develop pneumonia, ask about Valley Fever testing.

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