India's dengue becomes hyperendemic as all four virus strains spread across eight states

A nationwide molecular surveillance study led by the Indian Council of Medical Research (ICMR) and the National Institute of Virology in Pune analysed 6,889 laboratory‑confirmed dengue cases collected between 2023 and 2025 from 45 virus research and diagnostic laboratories across 25 Indian states and Union Territories. The study found that all four dengue virus serotypes (DENV‑1, DENV‑2, DENV‑3 and DENV‑4) are circulating simultaneously in eight states – Andhra Pradesh, Gujarat, Haryana, Madhya Pradesh, Maharashtra, Rajasthan, Tamil Nadu and West Bengal – confirming that dengue has become hyperendemic in parts of the country. DENV‑2 was the dominant strain, accounting for 51 % of infections, while about 7 % of patients were co‑infected with two or more serotypes, a condition linked to higher risk of severe disease such as hemorrhagic fever and shock. Health experts say the findings have major implications for India’s upcoming indigenous dengue vaccine, which must protect against all four serotypes to be effective. They also stress intensified mosquito‑control measures and early clinical monitoring as the monsoon season progresses.