The current weather conditions — high temperature and humidity — create an ideal environment for the female Aedes aegypti mosquitoes to breed, an entomologist said on Sunday.
Female Aedes aegypti mosquitoes are the main transmitters of the dengue virus.
Officials of the Kolkata Municipal Corporation (KMC) said on Saturday that they apprehended a rise in dengue infections post-Puja.
“The female Aedes aegypti mosquito survives in the temperature range of 16 degrees and 35 degrees Celsius. There are many examples, though, of mosquitoes surviving outside this range but that depends on the fitness of individual mosquitoes,” said Amlan Das, an associate professor of zoology at Calcutta University.
“Sixty to 70 per cent humidity is the best condition for such mosquitoes. Their activities such as feeding and foraging are at their peak in this range of humidity,” said Das, whose research interests include entomology.
Das warned that mosquito breeding would continue till the temperature and humidity dropped significantly.
In Kolkata, the minimum temperature remains below 16 degrees only in December and January. Over the past few days the maximum relative humidity has been more than 90 per cent and the temperature has been varying between 26 and 35 degrees.
The current spell of breeding and the huge gathering of people expected during the Puja may drive dengue infections, doctors at the KMC said. The rise in infections will be seen from a week after the Puja, officials fear.
“Someone in the crowd could be carrying the dengue virus. A mosquito can pick up the virus by biting the infected person and then pass on the pathogen to another person by biting him or her,” said an official.
Chandramouli Bhattacharya, a physician at Peerless Hospital, said a dengue patient remains infective for three to seven days from the onset of symptoms. “The mosquito can pick up the virus by biting the person during this period,” he said.
But if the mosquito bites another person soon, he or she will not be infected. “The virus takes between eight and 12 days to develop inside the mosquito, after which it is able to infect a person,” he said.
Dengue cases have almost doubled in a fortnight in Kolkata. A senior KMC official said 1,525 cases of dengue had been reported from Kolkata between January and September 18.
Deputy mayor Atin Ghosh had said earlier, while releasing a report on the most vulnerable wards till September 4, that “800 plus” dengue cases had been reported in the city till then.
Released: A collection of poems by Rajatsubhra Majumdar
A collection of poems by Rajatsubhra Majumdar was released at a programme at the Ramakrishna Mission Institute of Culture, Golpark, on Sunday. The collection is titled Ei Mohovaar, Ato Mayataan... The picture shows (from left) Rabindrasangeet exponent Anindya Biswas, poet Majumdar, theatre veteran Soumitra Mitra and actor-director Parambrata Chattopadhyay at the book release.
