Indian health authorities are trying to contain an outbreak of the Nipah virus, which has already infected five people near Kolkata, the country's third most populous city. The virus, which has no cure or vaccine, has a mortality rate that can reach 75% and is monitored by the World Health Organization (WHO) as a potential pandemic threat. The focus of infection was located in West Bengal, which led authorities to initiate large-scale contact tracing and impose quarantines to stop the spread. This week, three new cases were confirmed, joining two others previously detected, according to the Press Trust of India news agency. Among those infected are several healthcare professionals, including a doctor and three nurses from the private Narayana Multidisciplinary Hospital, in Barasat, around 25 kilometers from Kolkata. Narayan Swaroop Nigam, principal secretary of the Department of Health and Family, confirmed that one of the nurses is in a critical condition and in a coma. It is believed that this nurse became infected while treating a patient with severe breathing difficulties, who died before being able to be tested for the virus. The two nurses developed the first symptoms, such as high fever and respiratory problems, between New Year's Eve and January 2nd. In response, 180 people have already been tested and 20 high-risk contacts have been quarantined. The Nipah virus is transmitted from animals to humans, with fruit bats, common in India, being the natural hosts. Transmission can also occur through infected pigs or directly between people. Infection in humans may initially be asymptomatic, but quickly evolves into an acute respiratory illness. Symptoms include fever, headache and muscle pain, vomiting and sore throat. In the most serious cases, the virus can cause inflammation of the brain, leading to a coma within 24 to 48 hours. Due to its high lethality and epidemic potential, the WHO classified Nipah as a priority pathogen, calling for urgent research to develop treatments and vaccines for humans and animals.