IMMUNOGLOBULIN A-SPECIFIC CAPTURE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DIAGNOSIS OF DENGUE-FEVER

Dengue fever (DF) is usually diagnosed by testing for dengue virus imm unoglobulin M (IgM) by a capture enzyme-linked immunosorbent assay (EL ISA) (MAC-ELISA). However, IgM can last for months, and its presence m ight reflect a previous infection. We have tested the use of anti-deng ue virus IgA capture ELISA (AAC-ELISA) for the diagnosis of DF by comp aring the results of MAC-ELISAs and AAC-ELISAs for 178 serum samples t aken from patients with confirmed cases of DF. IgM appears more rapidl y (mean delay of positivity, 3.8 days after the onset of DF) than IgA (4.6 days) but lasts longer; the peak IgA titer is obtained on day 8. The specificity and the positive predictive value of AAC-ELISA are 100 %; its sensitivity and negative predictive value (NPV) are also 100% b etween days 6 and 25 after the onset of DF, but they decrease drastica lly when data for tests conducted with specimens from the first days o f infection are included, because the IgA titers, like the IgM titers, have not yet risen. AAC-ELISA is a simple method that can be performe d together with MAC-ELISA and that can help in interprating DF serolog y.