Incidence of dengue illness among children in an urban setting in South India: A population based study

Abstract

Objectives: Our main objective was to estimate population based dengue incidence estimates in children with fever >3 days. Methods: The study used the ‘National Surveillance System for Enteric Fever in India’ (NSSEFI) cohort at the Vellore site. Children aged 6 months to 14 years from a peri-urban setting in Vellore were followed up for a year for the presence of fever. All children who had fever >3 days were eligible for blood culture to diagnose typhoid. All children that presented with fever >3 days on alternate days of the week were also tested for dengue. Dengue incidence estimates were then calculated. Results: There were 6648 children followed up with a cumulative observation period of 5800 child years. There were 11753 fever episodes with 3171 (27%) episodes lasting >3 days. Totally, 784 children with 868 episodes of fever were tested for Dengue. NS1 antigen or Dengue IgM or both were positive in 82 (9.4%) of those tested for Dengue. Dengue PCR was positive in 33/64 (51.6%) of the samples positive samples. The annual incidence rate of dengue was 49.5 per 1000 child years among children with fever >3 days. Conclusions: There is high burden of dengue in peri-urban Vellore. Keywords: Children, Dengue, Fever, India, Surveillance