Singapore faces dengue threat from emergence of little-seen strain

In this picture taken on March 19, 2014, a National Environment Agency officer shows how Aedes mosquitoes caught in the top part of the Gravitrap, where an adhesive layer is, are removed. PHOTO: ST FILE

SINGAPORE - Singapore faces a fresh dengue threat this year, with the recent rise in infections stemming from a strain of the virus that has not been seen much for years.

The National Environment Agency said on Wednesday (Jan 15) there has not been an outbreak of DENV-3 virus here in the past three decades. This means that there is low immunity in the population to this serotype.

There are four dengue serotypes, with the outbreaks here caused by DENV-1 and DENV-2. DENV-2 has been the dominant strain since 2016.

The NEA said in a release: "We have seen an increase in Dengue virus serotype 3 cases and clusters over the past month.

"As Singapore has not seen a DENV-3 outbreak in the last three decades, the population immunity for DENV-3 is low and therefore more susceptible to transmission of the virus.

"It is thus critical that all residents and stakeholders work closely together with NEA to break the dengue transmission in these clusters, and curtail the spread of the virus."

It added that DENV-3 infections have been detected in three of the six largest clusters - in Jalan Bangau, Cashew Road and Jalan Paras.

Dengue infections have been on the rise for three weeks. Last week, 345 people were diagnosed with dengue - a 50 per cent rise over the number of infections seen in mid-December.

This is the highest number of infections seen at this time of the year, since 2016.

Said the NEA: "The high Aedes aegypti mosquito population in the community, current high number of dengue cases and increase in circulation of DENV-3 could lead to weekly dengue cases rising above current levels in 2020."

The NEA warned that the mosquito population, which is already high, may go up some more with the advent of warmer months.

It added that in some of the large dengue clusters, "we have detected mosquito breeding multiple times in the same homes".

At Bukit Mugliston, for example, mosquito breeding was discovered more than once in 10 homes. In that cluster, which has been active since October, 85 people have been infected including eight over the past fortnight.

Generally, one in five people diagnosed with dengue is so ill that they need hospital care.

Last year, the NEA took about 7,900 enforcement actions against premise owners for mosquito breeding. It also issued about 400 summonses and 26 stop-work orders to construction sites, while 13 contractors were charged in court for repeat offences.

The current rise in infections comes hot on the heels of last year's outbreak with 15,998 reported cases - the third highest annual number seen here. Twenty people died from dengue infections in 2019.

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