PREVALENCE OF HTLV TYPE-I AND TYPE-II AMONG DRUG-USERS IN KING COUNTY, WASHINGTON

We investigated the prevalence of human T-cell lymphotropic virus (HTL V) types I and II among drug users entering treatment in King County, Washington, between 1988 and 1990. Of 762 injection-drug users, 81 (10 .6%) were HTLV-positive; of 89 noninjection-drug users, 2 (2%) were HT LV-positive. Most (95.8% of those typed) were HTLV-II-positive. The re lationship between HTLV and demographic and behavioral characteristics was further evaluated among injection-drug users. The prevalence rate s for HTLV increased 25-fold from the youngest age group (15 to 24 yea rs) to the oldest (older than 45 years), after adjusting for race. Aft er adjustment for age, American Indians or Alaska Natives were 7.9 tim es, blacks 6.2 times, Asians or Pacific Islanders 4.7 times, and Hispa nics 4.1 times as likely as whites to be HTLV-positive. The prevalence of HTLV among heroin injectors was more than double that observed amo ng injectors of other drugs after adjusting for age, although this ass ociation was only marginally significant. The strong association betwe en HTLV prevalence and age suggests that HTLV-II (the predominant viru s) has been endemic among King County injection-drug users for some ti me. Its relatively high prevalence indicates that there is both an opp ortunity and a need to further investigate the epidemiologic and clini cal implications of HTLV-II infection.