Field evaluation of alternative HIV testing strategy with a rapid immunobinding assay and an agglutination assay.

A rapid immunobinding assay ('HIVCHEK', Ortho) and an agglutination assay ('Serodia-HIV', Fujirebio) were evaluated as an alternative to enzyme-linked immunosorbent assay (ELISA) and western blot under field conditions in Africa for detection of antibody to human immunodeficiency virus (HIV). 7106 specimens were tested at 25 laboratories in Kenya, Ghana, Senegal, and Zaire. HIVCHEK was used as a screening test, and serodia-HIV as a supplemental test to evaluate these assays in an alternative testing strategy to the standard ELISA/western blot testing procedure. In each country, HIVCHEK was more sensitive and specific than ELISA when compared with western blot. The sensitivity of HIVCHEK ranged from 87.0 to 96.3% and the specificity from 99.0 to 100%. The sensitivity and specificity of serodia-HIV ranged from 85 to 98% and from 88 to 98%, respectively. The sensitivity and specificity were affected by the presence of HIV-2 in Ghana and Senegal. Overall, with an HIV-1 prevalence of 14.8% in Kenya and 22.5% in Zaire, the sensitivities of the alternative strategy were 96.4% and 91.4%, the specificities 99.6% and 100%, the positive predictive values 97.6% and 100%, and the negative predictive values 99.3% and 97.9% for Kenya and Zaire, respectively. With this testing format there was an estimated average cost saving of up to 82% over the conventional strategy with ELISA/western blot. This procedure constitutes a reasonable alternative to the standard ELISA/western blot combination.