Histoplasmosis with mediastinal lymphadenopathy in an immunocompetent municipal water department employee in Texas: a case report.

Background: Histoplasmosis is an endemic mycosis that primarily affects the lungs, commonly found in the central and eastern United States, particularly the Ohio and Mississippi River valleys. While disseminated histoplasmosis (DH) is typically associated with immunocompromised individuals, rare cases have been reported in immunocompetent hosts following high-risk environmental exposures, particularly in high-risk occupational settings. Case presentation: We report a case of a 22-year-old immunocompetent male employee of a municipal water department in Texas who presented with fever, pleuritic chest pain, and progressive dyspnea. Initial workup suggested pneumonia, but lack of response to empiric antibiotics and evolving bilateral pulmonary infiltrates prompted further evaluation. A detailed exposure history revealed recent occupational exposure involving disruption of soil and debris in an area with stagnant water in an abandoned warehouse. Subsequent testing confirmed the diagnosis of histoplasmosis with positive urine antigen, elevated serum Conclusion: Both pulmonary and disseminated histoplasmosis should be included in the differential diagnosis for febrile respiratory illness in individuals with high-risk occupations regardless of immune status, including in regions not classically considered endemic. Early recognition and antifungal therapy are essential to prevent complications and ensure recovery.