Delhi records 20 dengue cases in January, highest in last 6 years: Civic bodies

The city recorded no dengue cases in the corresponding period in 2021, 2020 or 2019. It last added a dengue infection in January in 2018 (when the city recorded five cases) and three in January 2017

The Capital reported five new cases of dengue in the past week, said a report issued by Delhi’s municipal corporations, taking January’s overall tally to 20 patients, the most in the month since 2016, in what is an unusual and worrying trend for the city.

Delhi’s dengue season usually coincides with the monsoon, between end-June and October, since the humid, warm conditions, coupled with the abundance of stagnant water, provide the ideal breeding ground for the aedes aegypti mosquito that causes the vector-borne illness. (HT Archive)

So far this year, Delhi added eight dengue cases in the first week of January this year, and seven infections in the week after that.

The city recorded no dengue cases in the corresponding period in 2021, 2020 or 2019. It last added a dengue infection in January in 2018 (when the city recorded five cases) and three in January 2017.

Delhi’s dengue season usually coincides with the monsoon, between end-June and October, since the humid, warm conditions, coupled with the abundance of stagnant water, provide the ideal breeding ground for the aedes aegypti mosquito that causes the vector-borne illness.

While experts said the recurrence of dengue cases in January, when temperatures dip to their lowest in Delhi, was a cause for concern, municipal officials attributed this year’s numbers to the record rain the city has received this month.

The rain in Delhi so far this month has, to be sure, broken the month’s all-time record, according to data from the Met department, which is likely to have contributed to increased breeding by the aedes aegypti mosquito.

Delhi has got 88.2mm of rainfall so far in January, beating the previous record for the month (79.7mm) set in 1989, data maintained by the India Meteorological Department (IMD) between 1901 and 2022 shows.

The vector borne disease report for the week ending January 22 shows that no malaria or chikungunya cases have been reported so far.

The municipal corporations’ ‘action-taken’ report shows that domestic breeding checkers have so far detected 245 cases of positive mosquito breeding cases in the city, higher than 64 such instances last year and 96 cases detected in 2020.

A senior public health official said instances of dengue during the height of winter may indicate that the adult aedes aegypti mosquitoes are starting to adapt to local conditions, even as the person added that detections could also be attributed to the improved sentinel surveillance system, after dengue was declared a notifiable disease last year in October.

“Temperatures have, thankfully, remained low and mosquitoes need optimum [warm] conditions along with stagnant water for breeding,” a municipal official remarked.

Delhi recorded 9,613 dengue cases and 23 fatalities in 2021, making it the second worst annual outbreak on record.

Dr BK Tripathi, professor in the department of medicine at Safdarjung Hospital, said dengue cases used to flatten out during peak winters a few years ago.

“But it seems that the mosquitoes are now adapting to harsh climatic conditions, and civic bodies need to ensure that preparations and drives against controlling mosquito population should be carried out all through the year.”