Histoplasmosis in Missouri: historical review and current clinical concepts

Histoplasmosis is particularly common in Missouri, and many important clinical observations about the disease were made in this state in the 1950s and 1960s. When the AIDS epidemic spread to Missouri in the mid-1980s, histoplasmosis became recognized as a common and important opportunistic infection among Missourians with AIDS. Clinicians must maintain a high level of suspicion for histoplasmosis in any HIV-infected patient who presents with unexplained fever, particularly if the patient has evidence of hepatosplenomegaly, generalized lymphadenopathy, pancytopenia, abnormal liver function tests, or bilateral pulmonary infiltrates. The diagnosis of histoplasmosis can be established rapidly by observation of organisms on peripheral blood smear or bone marrow biopsy specimens or by Histoplasma Polysaccharide Antigen testing. The diagnosis can be confirmed by blood cultures in most cases. Histoplasmosis in AIDS is invariably fatal if not treated. Treatment consists of two phases: initial induction therapy and subsequent lifelong maintenance therapy. Amphotericin B and itraconazole are extremely effective for induction and maintenance therapy; fluconazole appears to be effective maintenance therapy. Strategies for the prevention of histoplasmosis in high risk patients are being evaluated currently.