Discrimination between primary and secondary dengue virus infection by using an immunoglobulin G avidity test

Discrimination between primary and secondary dengue infections is important, as the possibility of DHF is more in secondary infection. Therefore, there is need to develop a test that can distinguish between primary and secondary serological responses. The traditionally-used haemagglutination inhibition (HI) test, which is recommended by the World Health Organization, is complicated to perform. We standardized an enzyme-linked immunosorbent assay kit with some modifications to discriminate between primary and secondary dengue infections. Sera from 72 patients with acute dengue infection were tested. Seventy-one of the 72 patients were correctly classified (18 of 18 patients with primary dengue and 53 of 54 patients with secondary dengue). We conclude that this rapid and simple test is an excellent alternative to the HI test for discriminating between primary and secondary dengue virus infections during the acute phase of dengue.