Understanding Histoplasmosis and a Tennessee Cluster

State and local health agencies have identified a cluster of histoplasmosis cases in Middle Tennessee that began in September 2025. As of early January 2026, at least 18 cases have been reported in the Spring Hill and Thompson's Station area, while some public briefings have cited higher totals; the investigation into specific exposure sites is ongoing. Symptoms may appear three to fourteen days after exposure, so clinicians are being asked to report suspected cases promptly.

Histoplasmosis is caused by the fungus Histoplasma capsulatum, which lives in soil that is rich in bird or bat droppings. Infection occurs when people inhale spores that become airborne during demolition, excavation, or cleaning of contaminated sites. Most infections are mild and self-limited, although severe or disseminated disease can occur in people with weakened immune systems. The infection does not spread from person to person. Diagnostic tests include urine antigen detection and fungal culture, which may take several weeks; treatment ranges from oral itraconazole for moderate disease to amphotericin B for severe cases. Public health laboratories have been notified and several specimens have been sent for testing.