The Ministry of Health (MOH) is trying to get in touch with passengers on a recent Singapore Airlines flight to Auckland, New Zealand who were seated near a fellow traveller who had measles.
MOH is working with the airline and the New Zealand health authorities, a spokesman said.
"We will get in touch with the close contacts to check on their health status and to advise them to seek medical treatment if unwell," said the spokesman.
He added that the risk of a community outbreak of measles is low in Singapore as measles, mumps and rubella vaccination coverage is above 95 per cent.
Last year, there were 46 confirmed measles cases with those affected mainly young children under a year old. The first dose of vaccination is given at 12 months.
SQ flight 281, with about 270 passengers on board, left Singapore on Sunday and arrived in Auckland the same night.
It is believed that the infected traveller is a seven-month-old baby from the Philippines. The airline did not confirm this.