Prevalence and seasonal patterns of vector borne diseases in patients presenting with acute febrile illness in a tertiary care hospital in Puducherry- a prospective observational study.

Background objectives: Vector-borne diseases (VBD) are a major public health concern. Globalization, urbanization & climate change are reasons for the emergence and re-emergence of VBDs. In our study, we looked into the prevalence of VBD infections around our tertiary care hospital in South India. The objective was to determine the prevalence of common VBDs like Malaria, Dengue, Japanese encephalitis (JE), Chikungunya and Scrub typhus in patients with acute febrile illness (AFI).

Methods: This was a prospective laboratory based observational study. Blood samples from patients with AFI were tested for Dengue NS1 Antigen, IgM and IgG; and IgM antibodies for JE, Chikungunya and Scrub typhus using ELISA tests. Peripheral blood smear examination was performed for malarial parasite detection.

Results: Total 802 samples were analysed. The sample positivity rate for VBD was 63.6% (510/802 samples) On diving the positive results across seasons in the study period, the VBD positivity rates were 66.3%, 49.1%, 61.2% and 67.3% for the first post-monsoon, summer, monsoon and the second post-monsoon seasons respectively- a trend of increased rates noted during the post-monsoon seasons. 192 samples (23.9%) were positive for scrub typhus alone, 189 samples (23.6%) were positive for dengue infection alone, six samples (0.7%) were positive for chikungunya infection alone, 121 samples (15.1%) were positive for dengue plus scrub typhus co-infection, two samples (0.2%) were positive for dengue plus chikungunya co-infection, while 292 samples (36.4%) showed negative results. None of the samples were positive for malaria and Japanese encephalitis.

Interpretation conclusion: Scrub typhus and dengue were the most prevalent VBDs in concordance with the prevalence pattern noted in other studies in South India. Increasing awareness and surveillance of the VBDs, developing stringent control policies, easy access to testing and initiating early appropriate therapy can help reduce the incidence of VBDs.