Sars victim who infected 133 will remain in quarantine

As the death toll from severe acute respiratory syndrome (Sars) rose to 111 yesterday, with five more fatalities in China and Hong Kong, the authorities in Singapore were considering what to do with one of the disease's earliest and most medically extraordinary victims.

Esther Mok, a 26-year-old former flight attendant, is believed to have carried the disease from Hong Kong's Metropole hotel, source of the global outbreak, to Singapore on 1 March. Doctors at first did not know what was wrong with her and she was visited by members of her family and church. She was very sick and highly contagious – and passed the disease to scores of people.

Her father, mother and pastor have since died of Sars, her uncle is battling with the illness and her grandmother and brother are ill but stable. Most of Singapore's 133 cases of the illness and nine deaths can be traced to her. Yet, somehow, Ms Mok herself has survived.

Specialists call her a "super spreader", one of a handful of highly infectious individuals who have played a key role in transmitting the infection through local communities and round the world. Two other young Singaporean women who travelled to Hong Kong with Ms Mok also developed Sars after contact with the Chinese doctor at the Metropole hotel believed to have brought the infection from China. But they did not transmit the disease to others.

"Esther Mok infected the whole lot of us," the Health Minister, Lim Hng Kiang, said at a press conference.

Just why some people spread the disease so easily while others don't is not understood. American specialists from the Centres for Disease Control in Atlanta are due in Singapore to study the super-spreader phenomenon.

Two other super spreaders, a Canadian, Kwan Siu-Chiu, and an American Chinese businessman, Johnny Chen, fell ill after a stay at the Metropole and have helped spread the illness around the world. Unlike Ms Mok, they both died.

Chew Suok Kai, director of epidemiology and disease control in Singapore, said: "There are so many things we want to know about this disease but don't know yet. One of the key things we are working on is how the super spreader spreads." .

Meanwhile, Ms Mok, who has recovered, remains quarantined in hospital by the authorities who are reluctant to let her go, fearing the media frenzy expected to greet her release. Like "Typhoid" Mary Mallon, who famously infected dozens of people in the New York area in the early 1900s and was forced by the government to live alone on an island, Ms Mok is living her own exile in a hospital room networked with televisions and telephones.

Her quarantine prevented her from attending the memorial services of her parents, Joseph and Helen. Her sister, Rebekah, has taken a leave of absence to be with her. "We are all praying for her and for everyone involved," said Pastor Humphrey Choe of the family's church, the Faith Assemblies of God. He said the church had rallied round her.

She may have a difficult time when finally released. Since her admission a month ago, Singapore has quarantined about 1,000 people, ordering them to stay at home for 10 days or risk prosecution, and imposed strict travel restrictions. Gary Sival-ingam, a deliveryman, spoke for many when he said: "I feel sorry for her but you might wonder whether Singapore would be so badly affected had she not been in the wrong place at the wrong time."

An American specialist warned that the Sars virus was now unlikely to be eradicated from Asia. "I think we have to assume it is here to stay," said Dr Jim Hughes from the Centres for Disease Control.