Reliability of rapid diagnostic tests for HIV variant infection

The sensitivity of one ELISA method, six HIV-1/HIV-2 rapid screening tests, and one confirmatory test was evaluated in comparison with a third-generation EIA method (taken as the 'gold standard') and Western blot on well-characterized panels of sera. HIV diversity was represented by 50 HIV-1 group M subtype A to H, nine HIV-1 group O, 12 HIV-2, two HIV1+2 positive and six indeterminate Western blot profiles. Sensitivity during HIV-1 seroconversion was studied on 39 serial samples collected from six patients during early primary infection. Serial samples obtained from two primates during experimental primary SIV infection were used to mimic HIV-2 seroconversion samples. The sensitivity ranged from 100 to 94.6% according to the test. During seroconversion, rapid tests became positive 2-8 days later than the third-generation EIA. This reveals a major limitation of rapid tests, which are being recommended for use in developing countries. The lack of sensitivity seen during early HIV-1 seroconversion and/or limited specificity in some of the evaluated tests present serious limitations to their use in countries with high HIV incidence and variability. It is suggested that, as soon as possible, less sensitive rapid tests for blood bank screening should be abandoned in favor of highly sensitive rapid tests and/or more robust, more sensitive and cheaper ELISAs. These results stress the need for better screening tools and specific local evaluations.