HTLV-III Seropositivity in 1971–1972 Parenteral Drug Abusers — A Case of False Positives or Evidence of Viral Exposure?

To the Editor: The presence of antibodies to HTLV-III has been reported in banked serum samples obtained from parenteral drug abusers as early as 1979.¹ Whether this virus was introduced into this population earlier is subject to speculation. We recently completed a study of 1129 serum samples obtained from parenteral drug abusers throughout the United States (42 states and the District of Columbia) and 89 control samples from nonabusers of drugs, all collected during 1971–1972. The serum samples, which had been stored at -70°C for 14 years, were tested for antibodies to HTLV-III by two commercial ELISA procedures (Abbott Laboratories,….