Kolkata, March 22 (IANS): With three more persons - an elderly couple and their house maid - testing positive for coronavirus, the number of cases in West Bengal went up to seven in West Bengal on Sunday, Health Department officials said.

The son of the elderly couple, who reside on Panditiya Road in the Ballygunge area of South Kolkata, had earlier tested positive for the deadly virus. The youth had returned from the UK recently.

All four have been admitted in the special isolation ward of the state's primary referral hospital for infectious diseases in Beliaghata.

The swab samples of the elderly couple and their house maid were sent to the virology lab of the National institute of Cholera and Enteric Diseases (NICED), and the results on Sunday evening confirmed the infection.

Eight other members of the family have been kept at the state's quarantine centre in northeast Kolkata's Rajarhat.

Meanwhile, the condition of a 57-year-old man admitted at the AAMRI Hospital, Salt Lake, who was detected with the disease on Saturday evening, was serious. He was on ventilation support.

Earlier, a young woman from Habra in 24 Parganas (North) district tested positive for the infection on Saturday night, officials said.

The woman, in her early 20s, returned from Scotland on March 15.

She is now said to be stable at the ID Hospital, Beliaghata.

Earlier, a teenager who came back from United Kingdom recently, tested positive for the disease. Admitted at ID Hospital, he is also stable.