Discuss the clinical manifestations of histoplasmosis.

As already mentioned, the clinical manifestations depend on the quantity of organisms inhaled and immune status of the host. Only 1% of patients exposed to a small inoculum develop symptomatic disease; in contrast, 50% to 100% of persons exposed to a heavy inoculum develop symptoms. The majority of patients with symptoms develop a flulike acute pulmonary illness characterized by fever, chills, headache, myalgias, chest pain, and nonproductive cough. Progressive disseminated histoplasmosis occurs in 1 of 2000 acute infections. High-risk groups for disseminated disease include patients with impaired cellular immunity such as HIV infection, lymphoma, or leukemia, and also infants and the elderly. Rarely, there is a primary cutaneous form following direct inoculation into the skin.