Several people in the city are suffering from gastrointestinal infections, fever and cough and cold, doctors said.

The spate of infections started a few weeks ago.

Doctors blamed the temperature fluctuations for the spurt in fever, and cough and cold. Besides, many people who are outdoors for prolonged periods in the heat are drinking water that is not safe to drink.

The heat is also leading to bacterial contamination of food. Eating such food can cause gastrointestinal (GI) infections, one of them said.

“I am getting patients who are complaining of mild fever, cold and cough. The Celsius roller coaster — high temperatures, followed by rain and again a rise in the mercury — is creating ideal conditions for viral infections,” said Amitabha Saha, a critical care specialist.

Fluctuations in temperature boosts the activity of viruses, said a doctor. During extreme heat many drink chilled water and that makes them vulnerable to viral infections, said the doctor.

“There is a sudden fall in temperature in the throat area when one is drinking chilled water. This makes the upper respiratory tract vulnerable to infections,” said the doctor.

“The way temperatures have risen and dropped in the past seven to 10 days have made people vulnerable to infections,” said Saha, the head of critical care at Manipal Hospitals Mukundapur.

On May 17, the maximum temperature in Calcutta was 38.1 degrees. On May 21, it was 34.1. The heavy rain had a bearing on the Celsius on Wednesday. It cooled the surroundings. But the Celsius is tipped to go up again as the sun comes out.

A resident of Behala who was down with fever on Wednesday said he gulped down two bottles of soft drink on Tuesday while he was on an assignment outdoors for a long time. “It was very hot outside,” he said.

Critical care specialist Saha said a number of patients turning up in his clinic are also complaining about gastrointestinal (GI) infections.

Chandramouli Bhattacharya, an infectious disease specialist at Peerless Hospital, said GI infections is common during this time of the year.

“Food goes stale quickly when the temperature is very high. Eating such food will naturally lead to GI infections,” he said.