Prevalence of HTLV-III infection among New Haven, Connecticut, parenteral drug abusers in 1982-1983.

Abstract

The acquired immunodeficiency syndrome (AIDS) is etiologically linked to human T-cell lymphotropic virus type III (HTLV-III). Intravenous drug use is the primary known risk factor in 17% of US cases of AIDS. The authors report the presence of HTLV-III antibody confirmed by Western blot assay in at least 10% of a group New Haven Connecticut parenteral drug abusers in 1982-1983. The adequacy of using only enzyme linked immunosorbent assy (ELISA) testing in this risk group is questioned. Serum specimens were collected from 283 persons who were a part of a study of on-A non-B hepatitis from March 1982 until July 1983. All subjects had recently used drugs parenterally most were asymptomatic and many had moderate transaminase elevations and seropositivity for hepatitis B virus. Serum samples were stored under coade at -20 degrees Centigrade and were tested annonymously by ELISA (Abbott Laboratoties) according to the manufacturers specifications. Western blots were done with use of purified HTLV-III virion lysates prepared form infected H9 lymphocytes. 84 of the 283 samples (30%) were reactive on ELISA testing. 28 of the 84 ELISA-positive serum samples (33%) reacted with HTLV-III proteins on Western blots. 4 of these 28 samples were reactive only with p24. The other 24 serum samples were reactive with the full spectrum of HTLV-III related peptides. In all 148 cases of AIDS have been reported to the State of Connecticut Department of Health. 45 patients admitted intravenous drug use and in 31 cases it was the only known risk factor. Previous reports have noted a high prevalence of ELISA seropositivity for HTLV-III to parenteral drug abusers in areas of both high and low apparent AIDS risk in such abusers. Given the relatively high false positive rate of HTLV-III ELISA in low-risk groups and the known factors other than HTLV-III infection that account for some positive ELISAs it seems best for epidemiologic purposes to corroborate the high degree of HTLV-III ELISA seropositivity in parenteral drug abusers with a more specific test. Only 2 earlier studies used Western blots in addition to ELISAs. This study confirms that HTLV-III infection is not unusual in asymptomatic parenteral drug abusers in areas of the urban northeastern US despite the few reported AIDS cases in admitted parenteral drug abusers. The high false-positive ELISA rate (67%) in this study and the high false-negative ELISA rate (57%) observed in another study suggest that ELISA alone is not a useful screening test for HTLV-III infection in parenteral drug abusers.