Coccidioidal Meningitis in an Immunocompetent Patient: A Rare Central Nervous System Infection.

Coccidioidomycosis is a systemic fungal infection caused by Coccidioides immitis and Coccidioides posadasii. Although well recognized in parts of the southwestern United States, it remains underdiagnosed in Mexico and Central America. While most cases present as self-limited pulmonary infection, approximately 1% of immunocompetent individuals develop disseminated disease, with coccidioidal meningitis (CM) being the most severe manifestation. We describe a 46-year-old immunocompetent male from Oaxaca, Mexico, who presented with progressive headache, neurocognitive decline, and altered mental status. Initial cerebrospinal fluid (CSF) analysis suggested cryptococcal meningitis, yet cryptococcal antigen testing and fungal cultures were negative. Empirical antifungal therapy produced only partial improvement. Given his occupational exposure in Texas and evolving clinical course, coccidioidomycosis was suspected. Serologic testing (enzyme immunoassay, EIA) and a coccidioidin skin test were positive, and prolonged CSF culture ultimately yielded Coccidioides spp., confirming CM. High-dose fluconazole led to progressive neurologic recovery, and the patient remains asymptomatic on maintenance therapy. This case highlights the diagnostic challenges of CM in regions where coccidioidomycosis is not traditionally considered endemic. Non-specific presentations and initial negative studies may delay diagnosis, underscoring the importance of epidemiologic suspicion, repeated testing, and prolonged fungal culture. Early recognition and timely initiation of azole therapy are essential to prevent the high morbidity and mortality associated with this condition.