Cost reduction of unlinked testing for anti-HIV by investigation of pooled sera.

Anti-HIV-1 testing of pooled sera was found to be an excellent method of considerably reducing the costs and workload of public health surveillance programmes without the loss of important information. All 54 sera found anti-HIV-1 positive in diagnostic testing and 61 out of 70 sera (87%) found positive in surveillance studies were detected when tested at a dilution of 1:10 with anti-HIV-1-negative human sera. This acceptable loss of sensitivity could be reduced further by lowering the cut-off at which single sera of pools were tested: 96% of the above 70 anti-HIV-1-positive sera were detected. During testing of 618 pools containing 6180 sera from a low-risk population, lowering of the cut-off increased the number of pools with testing of individual sera from five (containing one confirmable anti-HIV-1-positive serum each) to only six (containing no anti-HIV-1-positive serum). Therefore, testing of pooled sera from a low-prevalence population group reduced the costs of testing about ninefold and technician time by about 25-50%.