Evaluation of dengue IgA antibody and NS1 antigen rapid tests as early diagnostic tests for dengue virus infection

BACKGROUND: Dengue is a major health problem. The lack of data on the usefulness of rapid diagnostic tests for early detection of dengue has generated interest in determining their validity.

OBJECTIVES: This research aimed to determine the validity of dengue IgA antibody versus NS1 antigen test as rapid diagnostic tests for early detection of dengue using Hemagglutination Inhibition test (HI) as standard reference.

METHODOLOGY: This study included 51 pediatric patients being evaluated for dengue in a private hospital from March 01, 2012 to October 30, 2012. Paired serum samples from patients suspected of dengue and had fever of not more than seven days were examined. Initial blood samples were collected on the first day of consult and tested for dengue IgA antibody, dengue NS1 antigen, and dengue HI tests. Second blood samples for HI were collected seven days after the initial extraction

RESULTS: The 51 serum samples used in this study came from 29 males and 22 females. From these samples, sensitivity of dengue IgA antibody was 80% with 95% CI (70-90) while specificity was at 50% with 95% CI(34-64) while dengue NS1 antigen which showed sensitivity of 27% with 95% CI (15-39) and specificity of 67% with 95% CI (54-86). IgA rapid test demonstrated 71% positivity in detecting acute primary dengue infection and 82% for acute secondary infection. NS1 detected 43% of primary infection and 24% of secondary infection.

CONCLUSION: Dengue IgA antibody rapid test was more sensitive than NS1 antigen test for early diagnosis of dengue and had better performance in detecting primary and secondary dengue.