Dengue strain's return a worry

Threat of new wave of infections with rise in DENV-2 cases since July; disease also claims 3rd life this year

This article was first published on Sept 14, 2014

Another dengue strain is resurfacing in Singapore, raising the spectre of a new wave of infections here. This warning by the National Environment Agency (NEA) yesterday came alongside the news that a third person has died of dengue this year.

An 81-year-old woman was first diagnosed with the mosquito-borne disease at Tan Tock Seng Hospital's emergency department last Saturday, and died in hospital yesterday.

Serangoon North Avenue 1, where the woman lived, is currently an active dengue cluster with at least two people hit by dengue. A cluster is formed when at least two cases are reported within 150m of each other within a fortnight.

In a joint statement, the Health Ministry and the NEA said yesterday that a mosquito breeding ground had been found in a pipe of an open drain in the area.

"Vector control operations to kill any infective adult mosquitoes and destroy any potential breeding habitats are ongoing," the agencies said.

The other two dengue deaths this year were an 85-year-old man who lived in Joo Chiat, and a 59-year-old woman who lived in Tampines.

In a separate statement, NEA also gave an update on the dengue situation in Singapore and Malaysia.

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," the 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.

Data in NEA's statement was based on information collected by the United In Tackling Epidemic Dengue network - a collaboration between both countries.

The authorities urged Singaporeans to remain vigilant as it is still the peak season for dengue, especially as most of the population do not have immunity against it.

Since January, there have been more than 14,600 dengue cases here. As of last evening, there were 62 dengue clusters, with eight high-risk red zones.

linettel@sph.com.sg