To the Editor: We would like to comment on the recommendation of Quinn et al. (Jan. 28 issue)* that all patients attending clinics for sexually transmitted diseases (STDs) be screened for the presence of infection with human immunodeficiency virus (HIV). In December 1986 we conducted blind studies of the seroprevalence of HIV among 200 consecutive persons from whom blood had been drawn for other purposes, at each of two STD clinics in the Detroit metropolitan area (the health departments of Detroit and Oakland County). Specimens initially positive on enzyme-linked immunosorbent assay (ELISA) underwent confirmatory testing by Western blot assay. Five.