Most humans with demonstrable antibodies to Histoplasma have experienced no symptoms at all, or they have endured a mild illness with full recovery. Some authorities estimate that prior to the advent of AIDS, approximately 95 percent of histoplasmosis cases were benign. Symptoms vary, and can include headache, fever, fatigue, chest pain, loss of appetite, a dry cough, joint pain, red lumps on the skin of the extremities, and other symptoms. Many cases resemble influenza or other respiratory infections. Recovery from a mild case can confer partial resistance to future attacks, but do not count on it.
Some individuals develop serious hypersensitivity reactions upon repeat exposure.
This is speculative, but given that our Grotto includes many experienced, globe-trotting cavers, it would not surprise me if histoplasmin skin tests show that most of us have been exposed to Histoplasma. I will not frighten you by giving detailed descriptions of the more serious, even fatal forms of histoplasmosis. Adverse sequelae include damage to the lungs and eyes, and dissemination into other organs. One man I know lost his eyesight to the point where he could no longer drive an automobile. The cause was not entirely clear, but damage to his retinas appeared to be related to his well-documented histoplasmosis.