By Sanjoy Majumder
BBC correspondent, Delhi
Indian health officials have launched a massive drive to contain an outbreak of dengue fever in the capital, Delhi.
Diseases such as dengue and malaria are common in the monsoon
Thousands of workers fanned out across the city spraying pesticides as part of a door-to-door campaign on Monday.
The mosquito-borne disease has claimed 11 lives over the past two weeks and more than 400 people have been affected in and around the capital.
Dengue fever can lead to high fever, with flu-like symptoms, and even to brain haemorrhage.
Delhi's health minister, Yoganand Shastri, has said that if the outbreak is not contained within the next 24 hours, the authorities will be forced to declare an epidemic.
"We have also started random checks of homes, offices and places where there could be stagnant water," city health official NK Yadav is quoted as saying by the AFP news agency.
What has alarmed many is the fact that one of the worst hit has been the country's premier public hospital, Delhi's All India Institute of Medical Sciences, where more than 30 people have been affected, including 18 medical staff.
One doctor has died.
Mosquito-bred diseases such as dengue and malaria are common in the monsoon season in India - the mosquitoes breed in stagnant water.
With no preventive vaccines available for dengue fever, the authorities are concentrating on cleaning up the city before things get out of hand.
"Since October and November are [the] most dangerous months for breeding of mosquitoes we have appealed to citizens to be on alert," Mr Yadav said.