Virulent dengue strain circulating in Delhi: Officials

Civic authorities said they have intensified anti-larvae drives and heightened vigilance for mosquito-borne diseases after a particularly virulent strain of dengue, type-2, has been found to be in circulation in the Capital

Civic authorities said they have intensified anti-larvae drives and heightened vigilance for mosquito-borne diseases after a particularly virulent strain of dengue, type-2, has been found to be in circulation in the Capital.

Virulent dengue strain circulating in Delhi: Officials

A senior civic official said that genome sequencing of dengue-positive samples in Delhi has shown that the dengue virus type 2 (DENV-2) strain was found in a majority of the cases.Officials did not share details, including how many samples were sequenced and how many of them were type-2. No deaths, however, have been recorded so far this year.

“Dengue has multiple strains. Type 1 can cause classic dengue fever along with chills and headaches while Type 2 can lead to haemorrhagic fever with shock and chills,” the official explained. Individuals with weak immune systems, such as the elderly, children and those with chronic illnesses, are particularly vulnerable.

“We are still in the initial phase of the monsoon cycle and focusing on destruction at the larval stages,” the official added.

Five-year municipal data on detection of mosquito breeding shows that the weekly count of mosquito larvae detection peaks between 32nd and 38th week of the year. With incessant rain, the breeding rate has increased over the last fortnight. “The mosquito causing dengue breeds in clear water and waterlogged areas and the primary method of preventing the dengue is through breeding site reduction. With regular rain spells over the last 10 days, waterlogging has increased in various parts of the city,” the official quoted above added.

MCD does not maintain data on strains. They come from tests carried out by AIIMS.

MCD action taken report recorded 9,803 sites with larvae over the last week, around 12% of the overall positive sites (82,870) detected between January 1 and August 8 this year.

According to MCD’s weekly vector-borne disease report dated August 8, at least 230 dengue cases have been reported so far in this year with an additional 76 cases where infection was acquired from other states. In 159 cases, the address of the patient was wrong or they could not be found.

However, the figures do not match health minister Pankaj Kumar Singh’s report after a review last week. “So far, a total of 1,179 dengue cases have been reported in Delhi. From the NCR region, outside Delhi, around 210–212 cases have been reported,” he said.

MCD officials did not respond to HT requests for comment on the discrepancy in the data.

According to MCD data from previous years, 315 cases were reported in 2025, 322 in 2024, 244 cases in 2023, and 64 cases in 2022 during the corresponding period. The civic body had officially stopped making weekly vector-borne disease reports public ahead of the G20 summit in Delhi. Type 2 was in circulation at the time.

Type 2 strain was also predominant during the city’s worst dengue outbreak in 2015 when 15,867 cases and 60 deaths were reported due to dengue over 12 months.

Dengue is a viral infection transmitted to humans by the Aedes aegypti mosquito. While it is typically not fatal and most people do not develop symptoms, those who do typically experience high fever, headache, body aches, nausea, and rash. Most recover within 1-2 weeks, but it can be fatal in extreme cases. Delhi saw four confirmed dengue-related deaths in 2025, 11 in 2024, 19 in 2023, and nine cases in 2022.