Risk factors

The chances of developing histoplasmosis symptoms increase with the number of spores you inhale. People more likely to be exposed include:

• Farmers
• Pest control workers
• Poultry keepers
• Construction workers
• Roofers
• Landscapers and gardeners
• Cave explorers
• Demolition workers

Most at risk of severe infection

Children younger than age 2 and adults age 55 and older have weaker immune systems, so they're more likely to develop disseminated histoplasmosis — the most serious form of the disease. Other factors that can weaken your immune system include:

• HIV or AIDS
• Cancer chemotherapy
• Corticosteroid drugs, such as prednisone
• Tumor necrosis factor inhibitors, often used to control rheumatoid arthritis
• Medications that prevent rejection of organ transplants