Tamil Nadu’s Health department on Sunday made public the dengue figures for a three-year period. The figures differ from those published by the Union Health Ministry’s National Centre for Vector Borne Diseases Control (NCVBDC) and come from a broader dataset that includes dengue cases diagnosed not only through dengue NS1 antigen test and IgM antibody tests, but also through rapid diagnostic tests.
The State Health department’s newly released figures show 56,863 dengue cases in 2023, 46,971 in 2024, and 25,585 in 2025. These are substantially higher than the corresponding figures published by NCVBDC – 9,121, 27,378, and 23,407 respectively. However, before 2026, NCVBDC figures had been cited in reports on Tamil Nadu’s dengue burden, including in studies published by the Directorate of Public Health and Preventive Medicine. The State Health department’s higher three-year figures were publicly reported before its release on Sunday. While the two datasets differ in the number of cases reported, both have the same number of deaths – 12 in 2023, 13 in 2024, and 12 in 2025.
State health officials clarified that NCVBDC took only cases confirmed by NS1/IgM tests, not rapid diagnostic tests, and hence the data variation. They maintained that these were the actual figures communicated by the department in the previous years and were captured by the Integrated Disease Surveillance Programme/Integrated Health Information Platform portal.
A reliable source said that infectious disease measurements must factor in population size and testing availability. “The Government of India takes into account laboratory confirmed cases by specific standardised methods, and no other rapid diagnostic tests, clinical diagnosis or platelet drops. States with better surveillance and reporting appear to have higher case counts than those under testing. So, the State had separate data to better understand the epidemic situation and to guide local control measures. While officially reporting laboratory confirmed NS1/IgM tests cases, the State used the remaining count through rapid tests, clinical diagnosis, and platelet metrics along with in-patient fever numbers to effectively manage the situation,” he said.
It may be recalled that Tamil Nadu had two dengue peaks in 2012 and 2017 recording 13,204 cases with 66 deaths and 23,294 cases with 65 deaths, respectively.
Published – September 21, 2026 11:44 pm IST
