New Delhi: Erratic rainfall in April has led to a rise in dengue cases in the capital, with over half of this year’s reported infections seen during the month.According to official data, Delhi has reported 107 dengue cases this year, of which 52 were recorded in April alone.In comparison, the city had reported 130 dengue cases till April in 2025, with only 32 cases in April. The corresponding figures were 35 in April 2024 and 18 in April 2023.Officials said intermittent rainfall prevents water from drying up completely, allowing stagnant water to remain in containers, drains and other waterbodies for longer periods. This gives 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.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.Officials said civic authorities have already intensified action, covering open spaces, drains, waterbodies etc. 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.In addition to 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.Apart from 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.
