The role of NS-1 antigen in early diagnosis of Dengue hemorrhagic fever in Yangon Children Hospital.

ABSTRACT

Detection of dengue virus NS1 antigen in patients’ sera serves as a supplementary assay for early diagnosis of dengue cases. This study evaluated the usefulness of NS-1 antigen for early diagnosis of dengue infection in children by use of a commercial immunochromato-graphic based SD Dengue Duo rapid test. The accuracy of SD Dengue Duo NS-1 antigen test was compared against a gold standard RT-PCR test in 117 children with suspected dengue infection attending YCH. All the children included in this study were tested for blood for complete picture and platelet count together with SD Dengue Duo rapid test. Among 117 samples, 65 serum samples were randomly selected and tested by RT-PCR. The sensitivity of SD Dengue Duo NS1 antigen assay was 40% (95% confidence interval) and specificity was 80% (95% confidence interval) as there were more secondary dengue cases in study population.The accuracy of NS1 antigen assay against RTPCR in patients with reduced platelet count showed that the sensitivity of NS1 antigen assay was 100% (95% confidence interval) and specificity was also 100% (95% confidence interval) when the platelet count was below 40,000.The result of this study demonstrated that the sensitivity and specificity of NS-1 antigen assay, at the time of low platelet count below 40,000, when specimens were collected within 5 days of fever, were relatively high compared to sensitivity and specificity of antibody detection. With the considerations for limitations such as NS1antigen assay being less sensitive in secondary dengue cases, in children, for diagnosis of dengue in early stage, with thorough clinical history and examination and also with platelet count, NS1 assay deserves inclusion in the diagnostic evaluation.