Purpose: To determine the incidence of active coccidioidomycosis among subjects infected with the human immunodeficiency virus (HIV) living in an area endemic for coccidioidomycosis and to identify factors associated with the development of active coccidioidomycosis in these patients.
Patients and methods: This was a prospective cohort analysis of HIV-infected subjects living in an area endemic for coccidioidomycosis in Arizona. On entry and at approximately 4-month intervals, subjects were interviewed and examined, and had spherulin skin testing and CD4 lymphocyte counts performed along with other tests. During each interval, it was determined whether the subject had developed active coccidioidomycosis according to established criteria.
Results: One hundred seventy subjects entered the study. Median follow-up was 11.3 months (range: 0 to 44 months). Thirteen subjects developed active coccidioidomycosis, with an estimated cumulative incidence of 24.6% by 41 months (95% confidence limits 8.2% and 41.1%). Risk factors associated with the development of active coccidioidomycosis in the cohort were a CD4 lymphocyte count of less than 0.250 x 10(9)/L and a diagnosis of acquired immunodeficiency syndrome. Factors associated with prior coccidioidal infection, including a positive spherulin skin test, length of residence in the endemic area for more than 25 months, and a prior history of coccidioidomycosis, were not associated with the development of active infection.
Conclusion: Active coccidioidomycosis among individuals infected with HIV is common in the coccidioidal endemic area. Immunodeficiency appears to be the major risk factor for the development of disease. Evidence of prior coccidioidomycosis, including a positive spherulin skin test, does not appear to predict the development of active infection.