Dengue: An analysis of epidemiological pattern over a six year period

Abstract

Introduction: Dengue is an arboviral infection transmitted among humans by Aedes aegypti, the urban vector and Aedes albopictus as a maintenance vector in sub-urban and rural areas. The diagnosis is routinely established by detection of NS1 antigen and/or by IgM antibodies testing. Dengue infects 50-100 million cases per year worldwide with atleast half million serious cases needing hospitalization. Therefore, it is necessary to keep the surveillance ongoing to timely look out for changes occurring in disease pattern over a geographical area. Aim: To study the epidemiological patterns of dengue virus infection in our region over a period of six years. Materials and Methods: The present retrospective study was undertaken in the Department of Microbiology, Government Medical College Hospital, Chandigarh during time period January 2010 to December 2015 on 10,774 serum samples from patients clinically suspected to be suffering from dengue infection. Samples were selected as per World Health Organization (WHO) criteria. All the samples were processed for the presence of dengue IgM antibodies by μ anti-body-capture Enzyme Linked Immunosorbent Assay (ELISA) MAC ELISA and/or NS1Ag by ELISA as per the instructions of the manufacturer. The data was analysed from the data sheets available. Results: During the time period, a total of 10,774 samples were processed and 2,449 (22.7%) samples came out to be positive for dengue virus infection. Marked seasonal variation was noted with 0-2 cases presenting during month of January to July but positivity peaked in post monsoon season in October (>70%) and tapered till December every year. The adult age group (16-45 yrs) showed maximum positivity (83.5%) with males affected more than females. Conclusion: The present study clearly shows that our region is endemic for the dengue virus infection and there is need to continuously monitor the transmission of the disease in the community, to plan effective measures, to control the spread of dengue virus infection the infection timely.