A total of 311 people from various districts are under observation, Health Minister KK Shailaja had said.
The samples of six people kept under watch after a college student tested positive for Nipah in Kerala have tested negative for the virus, authorities have said.
The Kerala government had on Wednesday said the condition of the college student being treated at a private hospital for Nipah was stable, while the condition of six others was improving.
A total of 311 people from various districts are under observation, Health Minister KK Shailaja had said, adding that samples collected from the patients currently being treated at the isolation ward of Kalamassery Medical College Hospital had been sent to National Institute of Virology in Pune.
According to the World Health Organisation, the incubation period (interval from infection to the onset of symptoms) is believed to range from 4 to 14 days.
The government has urged people not to panic and take precautionary measures to prevent the spread of the disease. The administration has launched an awareness campaign through the media to meet the challenge.
Union Health Minister Harsh Vardhan had also spoken to Shailaja on Tuesday to discuss the situation and assured all support from the Centre to the state.
A control room has also been set up and the Strategic Health Operations Centre of the National Centre for Disease Control has been activated, phone number for which is 011-23978046, a health ministry statement said in New Delhi.
According to state government figures, the Nipah virus had claimed 17 lives — 14 in Kozhikode and three in neighbouring Malappuram — in May last year.