The doctor who first identified hand, foot and mouth disease (HFMD) here 36 years ago is shocked at the recent rapid spread of the viral disease.

Since the current outbreak three weeks ago, more than 2,600 cases have been reported.

Dr Tay Chong Hai, 75, now a skin specialist in private practice, said it was 'unusual' to have 1,000 HFMD cases in a week.

A thousand people were infected two weeks ago.

'When the HFMD virus was first identified here in 1972, there were only 104 cases over three months,' he told The Sunday Times.

Dr Tay was first alerted to the HFMD virus in 1972 when his wife, Dr Caroline Gaw, then a polyclinic doctor, told him she was seeing cases of children with mouth ulcers and rashes.

After studying one patient's stool sample, he realised it was HFMD, which had already been found in the United States, Canada and Britain.

So far this year, 7,050 people have caught the disease. The majority are children. Although no one has died this time, one seven-year-old girl is in hospital with brain damage.

This may be the most serious HFMD outbreak since 2000, when an epidemic killed seven children.

Dr Tay said outbreaks can occur when there is a lowering of 'herd immunity' - that is, there are not enough immune individuals in a community to protect the rest from infection.

This year's spike and rapid spread could be due to more children in childcare centres, more air-conditioned spaces like malls and, possibly, a more contagious strain.

HFMD is a common childhood illness like chicken pox and measles. It is caused by intestinal viruses, the more common strains being Coxsackie virus and Enterovirus 71 (EV71).

Adults may get it as well but children, those under five in particular, are most susceptible.

The EV71 strain, which has infected some 16 per cent of HFMD patients here, is also more contagious, Dr Tay said.

Doctors say there will be outbreaks once every few years. Greater hygiene and isolation help in averting it.

Dr Tay said that unlike measles and chicken pox, there is no vaccine for HFMD. But he had some consolation for those hit by it.

'It's like measles and chicken pox. Once you get it, it's unlikely that you'll get it again.'

This story was first published in thesundaytimes on Apr 20.