Evaluation and use of NS1 IgM antibody detection for acute dengue virus diagnosis: report from an outbreak investigation.

The usefulness of detecting circulating non-structural protein 1 (NS1) IgM antibodies for diagnosing acute dengue virus infection was evaluated during an outbreak investigation along with other routinely used laboratory diagnostic methods. For the first time, the samples were also tested for NS1 antigen detection. NS1 IgM antibody detects all the serum samples that were positive for NS1 antigen detection within first 5 days of infection. The sensitivity of the NS1 IgM ELISA was higher when compared with RT-PCR and therefore, it could be used for early diagnosis.