Valley Fever: The Desert Fungus, the Pneumonia That Isn't, and the Fatigue That Lingers
Last updated September 4, 2026.
Valley fever, coccidioidomycosis, is a lung infection caused by breathing in spores of a fungus that lives in the dry soil of the US Southwest: Arizona and California's Central Valley above all. It is the great impersonator: it looks like pneumonia, it fails antibiotic after antibiotic because it is a fungus, and it is finally caught by the blood test someone thinks to order. Most people recover fully over weeks to months, and the fatigue, the symptom that outlasts everything, is real, documented, and temporary.
Who catches it and how
The spores ride the dust: windstorms, construction, gardening, and desert driving are the classic exposures, and you cannot catch it from another person. Most people who breathe the spores never know. Of those who fall ill, the picture is a flu-like pneumonia one to three weeks after exposure: fever, cough, chest ache, night sweats, crushing tiredness, sometimes a rash or joint pains, nicknamed desert rheumatism. Living in or traveling through the endemic region, even briefly, is the history that unlocks the diagnosis.
Valley fever is the pneumonia that fails antibiotics: a Southwest fungus caught by a blood test. Most people clear it with rest, the fatigue is the last symptom to leave, and stiff neck or confusion means urgent review.
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Outside the Southwest, valley fever is the pneumonia that does not respond, cycling through antibiotics because nobody asked about the trip. Inside the Southwest, doctors think of it constantly. The diagnosis is a blood test for antibodies, sometimes repeated because early tests can be negative, plus imaging. This pattern-matching matters for the patient: if a pneumonia is not responding and there is any Southwest travel in the last month, name the trip and ask about the test.
Treatment, and who needs it
Most cases need no antifungal: the immune system clears it, and rest, fluids, and time do the work, with the fatigue trailing behind for weeks or months. Antifungals, fluconazole usually, go to the severe pneumonias, the people at risk of spread, pregnancy, weakened immunity, diabetes, and higher-risk ancestries, and the rarer cases where the fungus travels beyond the lung to skin, bones, or the brain lining, which changes everything and is treated long and aggressively. The follow-up is a slow walk: symptoms are reviewed over months, and the return of energy, not any single test, is the true finish line.
- Pneumonia plus the Southwest equals the blood test. A pneumonia not responding to antibiotics, within a month of being in Arizona or the Central Valley, deserves the valley fever test. Name the trip; it changes the order.
- The fatigue is real and it is not damage. Crushing tiredness trailing the infection for weeks to months is the documented course, not weakness and not imagination. It lifts, and rest is treatment, not indulgence.
- Pregnancy and suppressed immunity change the rules. In those situations valley fever is treated promptly and watched closely, because spread beyond the lung is the danger. Anyone pregnant or immunosuppressed with this diagnosis belongs with a specialist early.
If you are weighing the risks and benefits of any medicine mentioned here, our overview of how medicines are tested and monitored for safety explains what those conversations are built on.
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Common questions
How do you catch valley fever?
By breathing dust carrying the fungus's spores in the US Southwest: Arizona and California's Central Valley above all, from windstorms, construction, gardening, or desert driving. It does not spread person to person, and most people who breathe the spores never fall ill.
Why did antibiotics not work?
Because valley fever is a fungus, not a bacterium, and no antibiotic touches it. The pattern of pneumonia failing antibiotic after antibiotic is the classic route to the diagnosis, and the blood test for antibodies is what finally names it.
Does everyone need antifungal treatment?
No. Most healthy people clear the infection on their own, and rest and time are the treatment, with fatigue trailing for weeks to months. Antifungals go to severe pneumonias and to people at risk of spread: pregnancy, weakened immunity, diabetes, and higher-risk ancestries.
How long does the fatigue last?
Weeks to months, and it is the last symptom to leave. It is documented, it is severe enough to affect work, and it lifts. Rest is part of the treatment, and a graduated return to activity is the right frame with your employer.
Can valley fever spread beyond the lungs?
Rarely, and it matters: the fungus can travel to skin, bones, or the brain lining, which is treated long and aggressively. Worsening breathlessness, high persistent fever, severe headache with a stiff neck, or confusion during valley fever means urgent review, not waiting.
I live in Arizona. Will I keep getting it?
Once you have had it, you are generally immune to a second round. The risk of a first infection comes with the territory, literally: dust storms, digging, and construction exposure are the moments to be thoughtful, and a well-fitted mask on the worst dust days is the practical habit.