Face masks have returned to the quiet residential neighbourhood of Melevaram near Farook College in Kozhikode. From the random scooter rider to the health workers huddled outside a family health centre, everyone is wearing them.The pervasive sense is not fear or anxiety, but caution. The reason is not hard to miss; a 43-year-old resident of the locality has been diagnosed with the deadly Nipah infection.Abdul Azeez, one of his neighbours, doesn’t seem to be overly worried though. “Health workers have told us that the infection doesn’t rapidly spread like COVID-19. They are visiting the place to monitor the situation every day. But, yes, most of us are wearing face masks while going out as a precautionary measure,” he says.The infected person has been on ventilator support at the Government Medical College Hospital (MCH), Kozhikode, since June 10. His close family members are already under home quarantine, says Venugopal, a relative who stays nearby.Contacts under observation“All his close contacts are now under observation. Lab tests are held if any of them exhibit any symptoms of the infection. So far, all of them have tested negative for the virus. Let’s hope he will survive the ordeal,” he adds.Health workers attached to the Ramanattukara municipality, in which the locality falls, are not taking any risks, however. A preliminary survey of the 300-odd houses in the area has already been completed. Rajul Koyadeen, medical officer attached to the local body, says a fever survey is going on to find out if any of the residents have had symptoms related to the deadly zoonotic disease. The Health department is also coordinating with the departments of Animal Husbandry and Forest as part of the ‘One Health’ initiative, while taking up containment steps. A team from the Indian Council of Medical Research too visited the area.Mortality rate of 75%Their alertness has its own background. Nipah, the virus causing the infection, has a mortality rate of up to 75%. It usually transmits from infected bats and other animals to humans and can also be transmitted directly between people. Fruit bats of the Pteropus species are the natural hosts of the virus. Nipah is also one of the pathogens in the World Health Organisation’s Research and Development Blueprint list of “epidemic threats needing urgent action”.