(CNN)India has put more than 300 people under surveillance after a 23-year-old man was diagnosed with the Nipah virus, a rare and often deadly disease.
Authorities in the southern Indian state of Kerala said Wednesday that they had identified 311 people who may have come in contact with the man and four other people displaying symptoms of the disease. All of them are under observation and have been told not to leave their homes.
"No risks are being taken with respect to this and hence we are observing people who came into contact with the patient for even a short period of time," said Dr. V. Meenakshi, a senior state health official.
The disease has resurfaced a year after an outbreak killed 17 people. More than 230 people were tested during that outbreak, which caused widespread panic in the Northern Kerala region.
However, this time state officials said they have quickly swung into action to isolate, observe and treat anyone who may have come into contact with the virus.
In a press conference on Tuesday, the Kerala State Health Minister K.K. Shailaja said that the 23-year-old man was in an isolation ward at a hospital in the Ernakulam district in Central Kerala and is currently in a stable condition.
She added that four other people, including two nurses who treated the patient, have been exhibiting signs of fever -- a symptom of the disease -- and were under strict observation. All four have been moved to an isolation ward but have not been officially diagnosed with the virus yet.
"I urge the people of Kerala to remain calm and to avoid panic," said Shailaja.
Nipah is a zoonotic virus, meaning it is transmitted from animals to humans and has a death rate of 40% to 75% for the infected. A Nipah infection can show zero symptoms, or it can cause fatal encephalitis (inflammation of the brain), with a range of possible wide spread complications.