PREVALENCE AND CLINICAL PROFILE OF DENGUE SEROTYPE CO-INFECTION AMONG SUSPECTED DENGUE PATIENTS

Abstract

Dengue fever is an important arboviral illness caused by dengue virus (DENV), which has four antigenically distinct serotypes, DENV-1 to DENV-4. Northern India continues to experience repeated dengue outbreaks, with a steadily rising disease burden. In Western Uttar Pradesh, the circulation of other arboviruses, especially chikungunya virus (CHIKV), has not been adequately investigated because dengue and chikungunya produce similar clinical features and are transmitted by the same mosquito vectors. Information on circulating dengue serotypes and arboviral co-infections from this region is still limited. This hospital-based cross-sectional study was conducted at a tertiary care centre in North India to assess the serological and molecular epidemiology of dengue infection, identify circulating dengue serotypes, and estimate the burden of chikungunya infection among patients presenting with dengue-like illness. Clinically suspected dengue cases were screened for dengue NS1 antigen and anti-dengue IgM antibodies by ELISA. Seropositive samples were further analyzed by multiplex RT-PCR for molecular detection and serotyping. Anti-chikungunya IgM testing was also performed to evaluate dengue–chikungunya co-infection. Among 375 suspected cases, 96 (25.6%) were serologically positive for dengue. Of 50 samples tested for CHIKV, 10 (20.0%) were positive, including 3 (6.0%) concurrent dengue–chikungunya infections. Dengue RNA was detected and serotyped in 60 cases. DENV-3 was most common (41.7%), followed closely by DENV 2 (40.0%), while DENV-1 accounted for 3.3%. No DENV-4 was detected. Mixed-serotype infection occurred in 15.0% of RT-PCR-positive samples. These findings show active co-circulation of multiple dengue serotypes and emphasize the need for integrated surveillance.