Histoplasmosis (also known as cave disease, Darling's disease, Ohio valley disease, reticuloendotheliosis,  spelunker ’s lung and caver's disease) is a disease caused by the fungus Histoplasma capsulatum'.f symptoms of histoplasmosis infection occur, they will start within 3 to 17 days after exposure; the average is 12–14 days. Most affected individuals have clinically silent manifestations and show no apparent ill effects.