Aims Early diagnosis of Dengue is important to improve patient outcomes and promote timely public health interventions. This study aimed at
studying the profile of paediatric Dengue viral infection,
comparing efficacy of NS1 antigen assay with MAC-ELISA for diagnosis of dengue, during both acute and convalescent phases and
assessing time frame for positivity of these tests.
Methods This was a prospective cohort study in the Paediatric department of a community hospital in a tropical developing country, during the period July 2011 to July 2012. The Institutional Review Board approved the study. Written informed consent was obtained from all parents. Clinical features of 178 children who presented with Dengue infection were studied. Dengue NS1 antigen, IgM and IgG ELISA were done on the day of admission irrespective of duration of fever. Other laboratory tests were done as per current protocol. Chi-square test and proportion test were used for analysis.
Results Majority of children (37.7%) was in the age group 11 to 15 years. 59.4% were males. The proportion of males was higher in extremes of age groups. Common clinical manifestations were fever (91.6%), rash (35.8%), hepatomegaly (33%), ascites (11.3%), bleeding manifestations (17%) and pleural effusion (3.7%). 21.7% had Dengue Haemorrhagic Fever and 7.5% had Dengue Shock Syndrome. Laboratory findings were thrombocytopenia (77%), leucopenia (24.5%) and raised SGPT (63.2%).
33% of children presented in acute phase (≤ 4 days) and 67% in convalescent phase (5–7 days: 53.8%, > 7 days: 13.2%).
94.3% were positive either for NS1 Ag or IgM antibody or both and 5.7% were clinically treated as dengue fever.
NS1 and IgM ELISA positivity were 88.6% and 51.4% respectively in acute phase and 63.38% and 92.8% respectively in convalescent phase (p < 0.001). Time frame for positivity of these tests is shown in table 1. NS1 antigen detection was very good in acute phase of both primary and secondary infections, but low in convalescent phase of secondary infections.