SINGAPORE - Another dengue strain is resurfacing in Singapore, raising the spectre of a new wave of infections here, warned the National Environment Agency (NEA) on Saturday.

There are four dengue strains, with the first two - DENV-1 and DENV-2 - the most common in Singapore. Last year, DENV-1 overtook DENV-2 as the most common strain. While it is still dominant, the NEA noted that since July, there have been an increasing number of DENV-2 cases surfacing.

"Singapore is watching this development closely, as the spread of the DENV-2 virus may result in a serotype switch, which could potentially lead to a wave of new infections," NEA's statement said. "Clusters with mixed virus strains are more challenging to control, as immunity to one serotype does not mean immunity to the other serotypes."

In Malaysia, DENV-2 is most common in the southern states of Johor and Malacca. These states have also reported a higher dengue fatality rate compared with the rest of the country. It remains unclear, however, if that means this strain of the virus is more virulent.