Surveillance of cryptococcosis in Alabama, 1992-1994

Although cryptococcosis is a significant opportunistic infection among patients with human immunodeficiency virus (HIV), there is conflicting information on rates of cryptococcosis among HIV-positive and HIV-negative patients. Precise state-wide epidemiologic data for cryptococcosis are not available in Alabama.

We conducted an active laboratory and hospital medical record-based surveillance for cryptococcosis in Alabama from October 1, 1992 to September 30, 1994. A case of cryptococcosis was defined as a patient's initial episode of cryptococcal disease and based on either a positive culture for C. neoformans from any normally sterile site, a positive latex agglutination serologic test for cryptococcal antigen in CSF or serum, or histopathologic findings consistent with C. neoformans.

Over the two year period, 153 cases were identified. The diagnosis was based on positive culture (37%), positive antigen (24%), positive autopsy culture (2%), and histopathologic findings (4%). Further, 33% of the total cases were diagnosed from combined positive culture, antigen, or histopathology. Of the total 153 cases, 55% were in HIV-positive patients and 44% were in HIV-negative individuals and one case (1%) had an unknown HIV status. The overall annual incidence rate of cryptococcosis was 1.89 cases per 100,000 population. The incidence was 1638.7 per 100,000 in the HIV-positive population and 0.84 per 100,000 in the HIV-negative population.

The first Alabama statewide active surveillance system for cryptococcosis confirms previous observations that rates of cryptococcosis are consistently higher in HIV-infected individuals than in their HIV-negative counterparts. In Alabama, cryptococcosis occurs more commonly in urban residents and in men. Cryptococcosis in HIV-positive persons is more likely to occur in the 20 to 44 year age group, whereas cryptococcosis in HIV-negative persons is more likely to occur in those greater than 45 years old.