Kolkata, Jan. 13 -- Two nurses infected with the deadly Nipah virus continue to remain on ventilatory support, with their condition described as extremely critical, hospital sources said on Tuesday.

The two are undergoing treatment at a private hospital in Barasat in North 24 Parganas in West Bengal, where they were employed.

Initial laboratory tests have confirmed the presence of the Nipah virus in samples collected from both nurses.

For final confirmation, the samples have been sent to the National Institute of Virology (NIV) in Pune.

Health officials said the situation is being monitored round the clock.

Following the detection of the cases, both the state and central governments have stepped up response measures.

Teams of expert d...