According to a Times of India report, most of the victims were under 30 years of age and stayed between Goregaon and Dahisar — an area within a short 1km stretch.

The disease spreads through the leptospira bacteria from animals to humans.

“Leptospirosis spreads when the urine of a dog or rat infected by the disease comes in contact with human skin,” Additional Municipal Commissioner (Health) Sanjay Deshmukh said. Leptospirosis was the largest monsoon killer in 2005 killing 66 people. In the 2007 deluge it left 79 dead.

“Out of the 12 victims, seven died within 24 hours of their admission to hospitals. The deceased included 10 men and two women. Eight of them had waded through flooded water,” Deshmukh said.

Experts are worried over the high death rate of patients with the infection.

As per the figures, 12 of 21 patients with the infection died between during the first week of July pegging the death rate at 57 per cent. However, the BMC’s epidemiology officer Mini Khetarpal told TOI that eight of the 12 patients had a history of wading through flood waters.

According to doctors, people with high fever, along with headache and severe bodyache, should be checked for leptospirosis. Leptospirosis has an incubation period of 3 to 21 days.