State health officials report 35 histoplasmosis cases clustered near Thompson Station, Spring Hill

State epidemiologists briefed the Williamson County Board of Commissioners on Jan. 12 about a cluster of histoplasmosis cases in the Thompson Station and Spring Hill areas.

Dr. Mary Margaret Phil and Dr. Emma Taylor Salmon of the Tennessee Department of Health told commissioners the agency confirmed an above‑expected number of cases after clinicians reported an unusual number of patients with histoplasmosis in November. As of Jan. 9, investigators had identified 35 cases clustered near the Williamson–Murray county line; the majority of case points reflect patients’ home addresses but some patients live elsewhere while working or engaging frequently in the cluster area.

Officials described histoplasmosis as a fungal infection (Histoplasma capsulatum) commonly found in soil enriched with bird or bat droppings. Most exposures are asymptomatic; only a minority of people exposed develop symptoms, which typically appear three to 17 days after exposure and often resemble a respiratory illness. The median age in this cluster is about 50; while there have been younger patients, younger people did not constitute a majority.

Investigators are conducting interviews to identify common exposures in the three weeks before symptom onset. Dr. Taylor Salmon listed higher‑risk activities—cave entry, extensive landscaping, cleaning chicken coops and construction—that can release spores. The team has engaged local health departments, municipal leaders and partners including the National Weather Service and local birders to track potential contributing factors such as bird migration. To date, TDH has not identified a single, definitive source for the cluster.

Most patients do not require antifungal treatment, but clinicians may prescribe antifungals or hospitalize patients if illness is severe; TDH said some investigation cases were hospitalized and that the department is reviewing medical records to determine whether deaths reported to investigators were directly attributable to histoplasmosis.

TDH advised residents to limit activities that disturb soil or droppings in affected areas, use protective masks when engaging in higher‑risk tasks, and consult health care providers if symptomatic. Officials said the investigation is ongoing and they will return with additional recommendations if new specific actions are warranted.

The commission asked for continued updates and for the health department to provide written guidance that can be distributed to residents and clinicians.