Background: To contribute to the knowledge of the frequency and distribution of infection by the HIV-1 in intravenous drug consumers (IVDC) the prevalence of infection in those in whom the voluntary serologic testing was practised and tendency over 5 years were studied.
Methods: The study included 2794 IVDC from centers of primary health care (70%) or those who attended directly (30%), from 1987 to 1991, to three Centers of Information and Prevention of AIDS located in the cities of Valencia, Alicante and Castellón in which the voluntary and free practice of the test of antibodies versus HIV-1 was performed. The serologic test (enzymoimmunoassay) was carried out in 2694 individuals whose positive results were confirmed by Western-blot. Risk factors of the infection in addition to sociodemographic data were collected by questionnaire.
Results: The estimated global prevalence was of 49.9% with confidence intervals of 95% (CI 95%) of 48.1% to 51.7%. Differences were observed according to the city with the highest being Valencia (55.3%, CI 95%: 52.8%; 57.8%) in comparison with Alicante (43.7%. CI 95%: 40.5%; 46.9%) and Castellón (41.3%, CI 95%: 35.6%, 47%). A decrease in prevalence was detected during the period studied (chi 2 of tendency = 6.37; p = 0.011), with this decrease only being produced in Alicante and Castellón. No differences were found with regard to sex in contrast to those found according to age, from 35.3% in those under 20 years of age to 59.5% in those over 29 years (chi 2 of tendency = 80.62; p < 0.0001). Only in the youngest age groups was a decreased tendency in prevalence found. The IVDC attended reported interchanging of needles at the time of consultation in 16.9% (CI 95%: 15.5%; 18.3%) with a descending temporal tendency from 27.7% in 1987 to 2.8% in 1991 (chi 2 of tendency = 14.18; p = 0.0001). Only 18.7% (CI 95%: 17.2%; 20.2%) of the IVDC used condoms in more than 66% of their sexual encounters of vaginal coitus. No differences were found with respect to sex or year of consultation.
Conclusions: The prevalence of infection by the HIV-1 in intravenous drug consumers requesting the serologic test is decreasing in the Community of Valencia. This reduction in frequency should be confirmed by estimated rate of incidence of seroconversion. The frequency of the use of condoms in intravenous drug consumers is low conditioning a high risk of extension of the epidemics by sexual transmission.