New Delhi: Erratic rainfall in April has led to a significant rise in dengue cases in the capital, with over half of this year's reported infections occurring during the month. According to official data, Delhi has recorded 107 dengue cases this year, of which 52 were reported in April alone.
Comparison with Previous Years
In comparison, the city had reported 130 dengue cases by April in 2025, with only 32 cases in that month. The corresponding figures were 35 in April 2024 and 18 in April 2023, highlighting a sharp increase this year.
Causes Behind the Surge
Officials attribute the rise to intermittent rainfall that prevents water from drying up completely, allowing stagnant water to remain in containers, drains, and other water bodies for extended periods. This provides mosquitoes sufficient time to complete their breeding cycle and multiply.
"While findings of the mosquito density index are yet to come out, we are requesting people to take precautions to avoid water accumulation on terraces and take indoor preventive measures to minimise mosquito breeding considering the trend is continuing," an official said.
Mosquito Density Index
The mosquito density index is an entomological surveillance metric used to estimate the abundance of mosquitoes — usually Aedes aegypti, the primary vector for dengue and chikungunya — in a specific area. By measuring larval, pupal, or adult mosquito populations, the index helps identify high-risk areas for disease transmission and guides targeted mosquito-control efforts.
Intensified Action by Civic Authorities
Officials said civic authorities have already intensified action, covering open spaces, drains, and water bodies. So far, around 1.2 crore house visits have been conducted, with 15,649 households found positive for mosquito breeding. The civic body has issued 16,261 legal notices over mosquito-breeding conditions and launched prosecutions in 1,712 cases. It has also issued administrative challans of Rs 50,000 and above in 358 cases, recovering over Rs 1 lakh.
Other Mosquito-Borne Diseases
In addition to dengue, Delhi has reported 29 malaria cases so far this year, including five cases reported last week. In comparison, 39 cases were reported during the same period in 2025, 35 in 2024, and two in 2023. Chikungunya cases remain low, with five cases reported so far this year, including two reported last week. This compares with six cases in 2025, 17 in 2024, and none in 2023 till the end of April.
Apart from the dengue cases reported so far this year, there are 119 cases where the infection was acquired from other states, or where the patient's address was incomplete or the patient could not be traced at the recorded address. In comparison, 107 such cases were reported last year.
