CAPTURE-RECAPTURE TO ESTIMATE THE SIZE OF THE POPULATION WITH HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 INFECTION

Estimating and monitoring the total number of people infected with hum an immunodeficiency virus type 1 (HIV-1) is a critical public health o bjective. No single epidemiologic methodology yields completely reliab le estimates. We used techniques originally designed to estimate the s ize of wildlife populations to complement estimates of the size of the population with HIV-1 infection in Lazio, Italy, during 1990 obtained from surveillance, surveys, and dynamic mathematical models. We used reports from four large testing sites to generate incomplete, partiall y overlapping lists of HIV-positive subjects. Log linear models yielde d estimated prevalences of 5.65 per 1,000 among males (95% confidence interval = 4.52-6.78) and 1.84 per 1,000 (95% confidence interval = 1. 34-2.33) among females in the population age 15-64 years. This method provides a simple and inexpensive means of obtaining accurate estimate s of the total number of HIV seropositives. It could be applied easily in all situations in which data from multiple sources are available.