The prevalence of HTLV-III/LAV antibodies among intravenous drug users attending treatment programs in California: a preliminary report.

Intravenous drug use is the primary risk factor in 17% of the cases of acquired immunodeficiency syndrome (AIDS) reported in the United States and intravenous drug users constitute the 2nd largest risk group after homosexual men. Recently antibodies to human T-cell lymphotropic virus Type III/lymphadenopathy-associated virus (HTLV-III/LAV) were also detected in as many as 87% of patients undergoing drug detoxification who did not have diagnosed AIDS. Most AIDS cases associated with intravenous drug use however have occurred in the northeastern United States with the greatest concentration in the New York City-New Jersey area. Similarly most seroprevalence studies of intravenous drug users have been performed in the same region. Epidemiologic data from the state of California 2nd only to New York in the total number of reported AIDS cases have attributed only 1.8% of AIDS cases to parenteral drug use. To date there have been few reports on the prevalence of HTLV-III/LAV antibodies in intravenous drug users in California. This letter reports the preliminary results of a study of the prevalence of AIDS virus antibodies among 345 intravenous drug users attending state-licensed treatment centers in 7 counties of California. In June 1983 we initiated a multicenter study of intravenous drug users enrolled in state-licensed methadone or alternative-treatment programs in California. Entry into the study was voluntary and participants were given the option of being informed or not about the results of their serologic testing. Serum samples were screened for antibodies to HTLV-III/LAV at the University of California AIDS Diagnostic Laboratory Davis with use of an enzyme-linked immunosorbent assay (ELISA) procedure developed and produced in our laboratory. All positive results were confirmed by indirect fluorescence assay and Western blot analysis. The 1st 345 samples analyzed represented a spectrum of urban and rural northern and southern regions with a wide range of reported incidences of AIDS. Only 1.7% of the total (6 of 345 samples) were positive according to ELISA and confirmatory tests. All the positive serum samples came from San Francisco and constituted 4.7% of the samples tested from its county. 37% of the samples came from San Francisco but only 4.3% from Los Angeles. Approximately 80% of the respondents reported having shared needles and other drug paraphernalia. Although these data are preliminary and underrepresent southern California at this time our results indicate that AIDS virus infection among intravenous drug users in California has not yet reached the alarmingly high levels observed in the northeastern United States. The high prevalence of needle sharing in this study however suggests that drug-taking behavior in CAlifornia is not significantly different from that of East Coast drug users. On the basis of sequential serologic studies from the United States and Europe one can predict a steady increase in the rate of seropositivity among intravenous drug users in California unless preventive measures are taken. The current low level of infection however provides this state with an opportunity to avert the serious problem currently faced by public health officials in the northeastern United States. (full text)