At a Glance
- A spike in histoplasmosis cases in Tennessee, with 36 confirmed illnesses and a reported death.
- The cluster began in early December 2025 and has affected Williamson and Maury counties.
- Public health officials have issued an advisory but the source remains unknown.
A sudden spike in cases of a rare fungal infection has rattled Tennessee, with 36 confirmed illnesses and a reported death. Public health officials are urging clinicians to suspect the disease when patients from middle Tennessee present with unexplained fever or breathing problems. The spike began in early December 2025 and has affected Williamson and Maury counties.
What Is Histoplasmosis?
Histoplasmosis is caused by inhaling spores of the Histoplasma fungus, most often the species Histoplasma capsulatum. In most people, exposure does not produce symptoms, but when it does, it can lead to mild pneumonia with fever, cough, chest pain, and body aches. In rare cases, the infection can become chronic or spread to the brain, resulting in serious, life-threatening illness.
The fungus thrives in soil that has been saturated with bird or bat droppings, and bats are considered a key vector for transmission. Outbreaks have previously been linked to bat exposure, such as a family who fell ill after visiting a bat-colonized cave in Costa Rica last year. In the United States, the fungus has also been contracted by people using bat guano as fertilizer for cannabis cultivation.
Because histoplasmosis is not contagious, it does not spread from person to person, which makes tracking outbreaks more challenging. Health officials emphasize that severe cases are more likely in individuals with weakened immune systems or those exposed to high levels of the fungus. The disease can remain dormant in the lungs for years before reactivating under stressful conditions.
Tennessee Cluster Timeline
In early December 2025, the Tennessee Department of Health issued a health advisory warning clinicians and labs about an uptick in acute and severe histoplasmosis cases in Williamson and Maury counties. At that time, the agency reported 18 known cases. The advisory urged laboratories to consider the infection in patients with respiratory symptoms.
A spokesperson for the Tennessee Department of Health told News Of Austin on Thursday that the tally had risen to 36 confirmed cases. The agency has not identified a clear source of the cluster, and the infection is not transmissible between people. The department is continuing to investigate potential environmental exposures.
Alyssia Brown Case
Alyssia Brown, a resident of Spring Hill, moved into a new home in October 2025 and began experiencing a persistent cough that refused to resolve. On December 8, she visited an emergency room where she was diagnosed with bronchitis and prescribed a steroid medication. Her condition continued to deteriorate, and she passed away on December 15.
Prior to her death, Brown requested that doctors test her for histoplasmosis after learning about the cluster from local reports. According to her family and roommate, the test returned positive for the fungus on December 18. Local detectives are investigating her death, and her family is awaiting autopsy results, as reported by the New York Times.
Brown’s case illustrates the potential severity of the infection, especially when diagnosis is delayed. Her family’s experience underscores the importance of early testing for histoplasmosis in patients with unexplained respiratory symptoms. The investigation into her death may provide clues about the cluster’s source.
Public Health Response
The Tennessee Department of Health has urged doctors to stay alert for further cases and to suspect histoplasmosis when treating patients from middle Tennessee with unexplained fever or respiratory illness. They recommend that clinicians consider the disease in patients who have had recent exposure to soil or environments with bird or bat droppings. The department issued a health advisory to clinicians and labs in the state.
The department continues to monitor the situation. Physicians are advised to include histoplasmosis in differential diagnoses for patients with unexplained fever or respiratory illness originating from middle Tennessee. The department has urged doctors to stay alert for further cases.
The Unknown Source
A clear source for the cluster has not yet been identified, and officials say it may never be located due to the ubiquitous nature of the fungus in Tennessee soil. The department notes that histoplasmosis spores can remain viable for years, making pinpointing a single exposure event difficult. “Histoplasmosis is commonly found throughout the soil in Tennessee, so it can be challenging to completely prevent exposure,” the Tennessee Department of Health representative told News Of Austin.
Because the fungus thrives in soil saturated with bird or bat droppings, investigators are looking at potential sites where such conditions exist, including abandoned buildings, farms, and areas with known bat colonies. A potential origin for these cases hasn’t been identified as of yet, and it’s possible that one will never be located, given the nature of this fungus, health officials say. The ongoing investigation continues to monitor new cases and seek ways to prevent additional infections.
Until a source is identified, public health officials recommend that residents avoid disturbing soil in areas with bird or bat droppings and wear protective masks when working in high-risk environments. They also emphasize that individuals with weakened immune systems should take extra precautions. The department will continue to monitor new cases and seek ways to prevent additional infections.
