Anyone working at a job or is present near activities where material contaminated with H. capsulatum becomes airborne, can develop histoplasmosis if enough spores are inhaled. After exposure, how ill a person becomes varies greatly and most likely depends on the number of spores inhaled and a person’s age and susceptibility to the disease. The number of inhaled spores needed to cause disease in not known. Infants, young children, and older persons, in particular those with chronic lung disease, are at greatest risk for developing the histoplasmosis. The following list of occupations and hobbies are commonly associated with higher risks of exposure to H. capsulatum spores; bridge inspector, chimney cleaner, construction worker, demolition worker, farmer, gardener, HVAC system installer, microbiology worker, pest control worker, restorer of historic or abandoned buildings, roofer, and cave explorer. If someone who engages in these activities develops flu-like symptoms days or even weeks after disturbing material that might be contaminated with H. capsulatum, and the illness worsens rather than subsides after a few days, medical care should be sought immediately.