Histoplasma capsulatum is endemic in which region of the United States?

Histoplasma capsulatum is endemic in which region of the United States?

• A. Pacific Northwest
• B. Mississippi/Ohio River valleys
• C. Northeast United States
• D. Southeast United States

Answer: (B)

The distribution of Histoplasma capsulatum is tied to soil enriched with bird or bat droppings, where the fungus grows in its mold form and releases infectious spores that are inhaled when disturbed. In the United States, the classic endemic region is the Mississippi and Ohio River valleys, where warm, humid soils with accumulated guano create ideal ecological niches. This is the area most strongly associated with histoplasmosis, with many cases linked to activities that disturb soil or bat roosts, such as cave exploration or cleaning chicken houses. Regions like the Pacific Northwest or Northeast aren’t the typical endemic zones for this fungus, while the Southeast overlaps with the endemic area but is not the defining region.

The distribution of Histoplasma capsulatum is tied to soil enriched with bird or bat droppings, where the fungus grows in its mold form and releases infectious spores that are inhaled when disturbed. In the United States, the classic endemic region is the Mississippi and Ohio River valleys, where warm, humid soils with accumulated guano create ideal ecological niches. This is the area most strongly associated with histoplasmosis, with many cases linked to activities that disturb soil or bat roosts, such as cave exploration or cleaning chicken houses. Regions like the Pacific Northwest or Northeast aren’t the typical endemic zones for this fungus, while the Southeast overlaps with the endemic area but is not the defining region.