Evaluation of saliva-based diagnostic test kit for routine detection of antibodies to HIV.

The study was carried out to determine the reliability of a saliva based test kit for routine detection of HIV antibodies. 150 paired plasma and saliva samples were collected from 50 patients who were known to be positive for HIV-I and 100 others whose HIV serostatus were previously unknown. All the plasma samples were tested for HIV antibodies using Novopath Immunoblot Technique (as the gold standard), Wellcozyme (Murex) ELISA, Latex Agglutination Test (Capillus) and SeroCard Kit. The saliva samples were screened for HIV antibodies using SalivaCard Test Kit. All the 50 known positive patients tested positive when retested with immunoblot and 9 of 100 whose serostatus were unknown also tested positive giving a total of 59 positive results and 91 negative results. Of the 59 positive results, 59, 57, 58 and 47 were correctly identified as true positives by Wellcozyme, Capillus, SeroCard and SalivaCard respectively. Of the 91 negatives, 90, 91, 90 and 85 were correctly identified as true negatives respectively. Sensitivities in the same order were 100%, 97%, 98.3% and 79.7% whilst specificities were 98.9%, 100%, 98.9% and 97.8%. Whereas evaluation parameters for Wellcozyme, Capillus and SeroCard test kits met the criteria for licensure of a test kit as a routine test method for HIV antibody detection, the SalivaCard values fell far short of the stipulated criteria. The Sensitivity, Test Efficiency and Positive Predictive Values of 79.7%, 88% and 67.8% respectively obtained for SalivaCard are too low and the test kit cannot be recommended for routine use as HIV antibody detection kit.