A Comprehensive Study on the 2012 Dengue Fever Outbreak in Kolkata, India

Abstract

Background. Dengue viruses (DV) belong to the family Flaviviridae, with four serotypes referred to as DV-1, DV-2, DV-3, and DV-4. A large-scale outbreak of dengue fever occurred in 2012 involving several districts of West Bengal. Objective. To present a comprehensive picture of the dengue fever outbreak in 2012 and to identify the prevailing serotypes. Materials and Methods. Serum samples were collected from suspected dengue fever cases. Samples from fever cases <5 days duration were tested for dengue NS1 antigen employing Pan Bio (Australia) NS1 ELISA kit. Serum samples of ≥5 days fever were tested for dengue-specific IgM by MAC ELISA test kit prepared by the National Institute of Virology Pune, India. Serotyping of dengue samples was done by dengue-specific reverse transcriptase polymerase chain reaction (RT-PCR). Results. The number of dengue cases in 2012 clearly outnumbered the dengue cases in 2010 and 2011. The majority of the cases were in the age group 11–30 years with a male preponderance. Outbreak occurred during the months of Aug.–Nov. indicating increased vector transmission in the monsoon and postmonsoon periods. The prevailing serotypes in this outbreak were Den1, Den3, and Den4.