Hyderabad: Dengue mosquitoes don’t lose sting even after dark

If you are among those who thought or believed that dengue mosquitoes bit only early in the morning or before dusk, then beware! It’s time you stopped getting complacent at night, because city doctors say the dengue-causing aedes aegypti mosquitoes are now biting even at night.
In the past couple of years, there has been a spurt in dengue cases in Hyderabad. In the last one week itself, 21 cases were reported in the city, as per official records.Various private hospitals are recording between three and five cases per week currently.

With most offices working round the clock, the diurnal pattern of mosquitoes has changed due to the micro-environment that allows them to thrive. With both dengue and chikungunya cases affecting people, especially in those offices where night shifts are common, doctors say it has helped them firm up their analysis. Analysing data for the last two years, which shows a spike in cases to 4,359 in 2018 from 3,827 in 2017, doctors say this year could be worse.
“Living in such a micro-environment with very little range of temperature variation, makes mosquitoes indifferent to seasons or timings of the day. Such micro-environment exists in offices, homes, malls and construction sites, which make it ideal breeding grounds for mosquitoes. This kind of an environment triggers a change in the diurnal pattern of mosquitoes, with most becoming active at night as well,” said Dr Rahul Agarwal, senior consultant physician, Maxcure Hospital.
“The artificial lighting as well as temperature-controlled ambience, including air conditioners, help in breeding of mosquitoes more,” said Dr K Shankar, director of Institute of Preventive Medicine.
The World Health Organization (WHO), too, has underlined this aspect. The WHO website states: “They breed indoors and are capable of biting anyone throughout the day. The indoor habitat is less susceptible to climatic variations and increases the mosquitoes’ longevity.”
With changing patterns, dengue is now an all-season virus, unlike three years ago when the cases used to be recorded between June and September. The staterun Gandhi Hospital alone has seen a record number of dengue cases in 2017, with substantial numbers being recorded during the off season. As per official statistics, more than 1,200 cases were recorded in Gandhi Hospital alone in 2018, of which 102 were in December alone.