One hundred and fifteen dengue cases have been reported from Calcutta so far this year, mayor Firhad Hakim said in the Assembly on Thursday.

The number is lower compared to the past few years, but experts warned that any complacency would lead to a surge in cases, especially with the arrival of the monsoon and a rise in the volume of rainfall predicted by the Met office.

“In 2022, the number of dengue-affected people in Kolkata was 8,815. In 2023, the count was 1,402; in 2024, it was 1,324. So far this year, 115 people in Kolkata have been affected by dengue,” said Hakim, also the minister for urban development.

This week’s rain has created conditions ideal for a renewed spurt in dengue. The only way to prevent an outbreak is to destroy all potential mosquito breeding sites, public health professionals said.

Intense and heavy rain washes away mosquito larvae, while persistent showers, like what the city has been witnessing, create mosquito breeding sites.

The low-intensity rain has created small puddles that are ideal for the Aedes aegypti mosquito, the transmitter of the dengue virus, to breed.

A city-based doctor and public health expert told Metro: “There is no room for complacency. Now that monsoon has arrived, the civic body and other agencies should undertake cleaning drives regularly. We must not let our guard down”.

According to officials of the Kolkata Municipal Corporation (KMC), workers at the grassroots level have been instructed to check for water accumulated in small containers. The Aedes aegypti mosquito can breed even in a spoonful of water and it takes around a week for adult mosquitoes to emerge from eggs.

Another KMC official said garbage stacked anywhere should be cleaned to eliminate potential mosquito breeding sites.

“We need a concerted effort by all agencies to prevent a surge in dengue numbers. Small containers that can be potential sites for mosquitoes to breed should be taken care of. Rooftops, pavements and garbage dump yards, all the places should be scanned,” said Debashis Biswas, officer on special duty and chief vector control officer of the KMC.