PROSPECTIVE-STUDY OF HISTOPLASMOSIS IN PATIENTS INFECTED WITH HUMAN-IMMUNODEFICIENCY-VIRUS - INCIDENCE, RISK-FACTORS, AND PATHOPHYSIOLOGY

Histoplasmosis is a common opportunistic infection in patients with hu man immunodeficiency virus (HIV) infection who reside in areas where H istoplasma capsulatum is endemic. We undertook a prospective study of a cohort of 304 HIV-infected patients in Kansas City from October 1990 through March 1993 to define the incidence-specific risk factors, and pathophysiology of histoplasmosis. The annual incidence of histoplasm osis was 4.7%; 74% of the patients with histoplasmosis were symptomati c (all of whom had disseminated disease). A history of exposure to chi cken coops, a positive baseline serology for complement-fixing antibod ies to Histoplasma mycelium antigen, and a baseline CD4(+) lymphocyte count of <150/mu L were associated with an increased risk for histopla smosis. Histoplasmin reactivity and the presence of pulmonary calcific ations were not useful markers for patients at high risk. Symptomatic infection occurred in 9.9% of patients with evidence of prior exposure to H. capsulatum, in 4.0% of patients without documented prior exposu re, and in 3.0% of patients who were anergic; these findings suggest t hat the pathophysiology of histoplasmosis in patients with AIDS involv es reactivation of latent infection in some cases and dissemination of exogenously acquired infection in other cases.