SINGAPORE may be facing its most serious hand, foot and mouth disease (HFMD) outbreak since the epidemic in 2001 that killed seven children.

More than 1,000 children fell ill last week - the highest number of weekly infections since 2001.

Of the 13 children hospitalised last week, one is seriously ill, with inflammation of the brain.

She was diagnosed with HFMD on April 3. Instead of getting better, her condition worsened and she had to be hospitalised a week later, on April 9.

She is still in hospital, but her condition has improved, said the Health Ministry in a statement on Tuesday.

HFMD is endemic in Singapore, with children catching the virus almost daily. Symptoms include fever, headache, sore throat and the red rash usually on limbs and in the mouth that give it its name.

It is spread through bodily fluids, which is why it can spread like wildfire among young children who share toys they may have put into their mouths.

In children, it is usually a mild disease that lasts about a week. In adults, it can be more serious.

The disease can be caused by several types of viruses, with the most dangerous being the enterovirus-71 or EV71.

The Ministry said on Tuesday that 16 per cent of HFMD infections last week were caused by this EV71.

Schools, kindergartens and childcare centres have all been on the alert since last month, when the number of infections began to climb.

The number of cases reported over the past four weeks has stayed above the 600-a-week mark, signalling an epidemic. So far this year, 6,315 people have caught the disease.