Epidemiological Investigation of a Chikungunya Fever Outbreak in a Tribal Population of Dakshin Dinajpur, West Bengal, India

Introduction Chikungunya is a re-emerging viral fever transmitted by the bite of infected Aedes mosquitoes. We investigated the outbreak with the objective of finding out the cause of fever with joint pain and recommended preventive measures. Methods This outbreak investigation was done at the village of Gangarampur block of Dakshin Dinajpur district, West Bengal, India. House-to-house search for active cases was conducted at the village during October - November 2024. The outbreak was described by time, place, and person distribution. Epidemic curve, spot maps, and analytical tables were constructed to determine the relation of the outbreak. Blood samples were tested for dengue, chikungunya, malaria, and scrub typhus. Entomological surveys were also done to measure larval index. Result A total of 35 cases were identified, with an overall attack rate of 2.97%. Majority of the cases were female (57.2%) and age group of 31 - 50 years (48.8%). In almost all cases, patients developed fever with joint pain. The epidemic curve showed maximum cases in the month of November 2024. Chikungunya, dengue & scrub typhus positivity was 51.7% (15/29), 3.4% (1/29) & 6.9% (2/29) respectively. No such significant entomological findings were observed. Discussion We initiated the investigation on the presumption of a dengue outbreak, but after blood samples reporting, it was revealed that cases were predominantly (51.7%) Chikungunya, 6.9% were Scrub Typhus and mixed infections of Scrub Typhus with Chikungunya and 3.4% were Dengue. Without any complications, almost all cases were managed at home. Extensive awareness generation programmes were conducted for the prevention and transmission of fever.