USE OF POOLED RESIDUAL LABORATORY SERA TO ASSESS HUMAN-IMMUNODEFICIENCY-VIRUS PREVALENCE AMONG PATIENTS IN ITALY

An anonymous unlinked seroprevalence study of human immunodeficiency v irus (HIV) infection was performed by testing pools of ten sera remain ing from specimens submitted consecutively to clinical pathology labor atories at 18 Italian public hospitals during four consecutive days in April 1991. Sera from positive pools were retested individually by th ree different enzyme immunoassays (EIAs) and considered positive if re active by all three assays. Only the sera with discordant ELA results were retested by Western blot. Of a total of 22,590 sera, 278 were HIV positive (1.2 %). The highest rates were seen in hospitals located in metropolitan areas (1.5 %), in infectious disease departments (28 %) and in drug addiction treatment units (28 %); among men aged 21-30 (4. 6 %) and 31-40 years (4 %); and among women aged 21-30 years (1.6 %). The distribution of seropositive patients by gender and age group sugg ests an increasing role of heterosexual transmission of the infection. The presence of anti-HIV antibodies in sera from patients of both sex es, in all age groups, and from all clinical settings reinforces the n eed for health care workers to adhere to universal precautions issued to prevent occupational bloodborne infections.