He is Mr E. C. Sng, who caught the bug overseas. He believes he caught the virus while playing golf at Jakarta's prestigious Jagorawi Golf & Country Club a month ago.

He has not passed on the disease to anyone and is no longer infectious.

So far, 13 people have been infected locally, and another four, including Mr Sng, caught the virus overseas.

Like dengue, chikungunya is spread through the Aedes mosquito. It spreads if an infected person is bitten by an Aedes mosquito within days of getting symptoms, which include fever, headache, fatigue, nausea, vomiting, muscle ache, rash and pain in the joints. The mosquito spreads the virus to those it subsequently bites.

An Indonesian golfer friend of Mr Sng's told him that there had been a handful of cases at the club, and that, in a town 30km to the south, more than 150 people had come down with the disease.

The ministry said on Thursday the threat of chikungunya spreading here was real.

'The virus can be carried into Singapore and the presence of the Aedes mosquito means the threat will remain,' said its spokesman.