A retrospective study of dengue seroprevalence, secondary infection and seasonal trends in Western Uttar Pradesh, India

Background & objectives: Dengue, caused by a single-stranded RNA virus of the Flaviviridae family of Arboviruses, remains a severe public health threat, especially in tropical and subtropical regions. This study aimed to determine the prevalence, seasonal trends, and secondary dengue infection cases in the western area of Uttar Pradesh. Methods: A retrospective study was conducted at VRDL, Department of Microbiology, Uttar Pradesh University of Medical Sciences, analyzed 11,618 serum samples over the last three years, from January 2022-December 2024. Serum samples from suspected cases were subjected to NS1 antigen, IgM, and IgG antibodies enzyme-linked immunosorbent assay (ELISA). Results: 11618 samples were tested with 2158 (18.57%) positive samples in the last 3 years. A total of 9571 samples were tested for NS1 Ag, of which 1459 (15.24%) were positive. There were 11454 samples tested for IgM, of which 789 (6.87%) were positive. Out of 9215 samples tested for IgG, 1068 were positive (11.58%). A higher percentage of positivity was observed in the age group 11-20 years, and males (18.68%) were more affected than females (16.41%). Peak cases showed during September-November, which correlates with the monsoon season, while transmission declined in winter. Interpretation & conclusion: The study found that young adults, particularly males, were most affected. An understanding of seasonal patterns and the need for early diagnosis and vector-control measures are crucial to managing effective dengue outbreaks.