Dengue cases expected to rise at year-end as Aedes mosquito population increases

More than 4,500 dengue cases have been reported this year. ST PHOTO: LIM YAOHUI

SINGAPORE - Dengue cases in Singapore are expected to increase at the end of the year as the Aedes mosquito population rises, the National Environment Agency (NEA) warned on Tuesday (Oct 26).

And with more people staying in and working from home due to Covid-19, there is greater exposure to the mosquitoes which feed in the day, leading to a potentially higher risk of dengue transmission, said the agency.

More than 4,500 dengue cases have been reported this year and there are currently 12 active clusters in Singapore.

The agency urged the public to stay vigilant and not let their guard down, as dengue remains a serious public health threat, although recent weekly dengue cases have been lower than the same period in 2020.

It noted the population of the Aedes aegypti mosquito - which spreads the dengue virus - increased by about 22 per cent in September this year, compared with August.

The mosquito population is high in some areas, including Geylang Bahru, Jalan Berseh, Kelantan Lane, Kelantan Road, Jelapang Road and Woodlands Street 81.

NEA also warned that the spread of dengue virus serotypes previously uncommon here has increased, meaning more people would not have immunity against infection from these serotypes.

Since 2016, the predominant dengue virus serotype in Singapore was serotype 2 (DENV-2). But since May this year, there have been more cases of serotype 3 (DENV-3), which now make up more than 50 per cent of cases sampled.

Hence, DENV-3 has replaced DENV-2 as the dominant serotype, NEA said.

This serotype was detected in 121 of 254 dengue clusters where serotypes were identified this year, including the ongoing cluster at Florence Road and Hougang Avenue 2, which has 195 cases.

NEA added that the incidence of Aedes aegypti mosquito breeding detected in homes remains high.

"If left unchecked, the current high Aedes aegypti mosquito population, coupled with circulation of the previously uncommon DENV-3 and a sizeable proportion of people staying in and working from home, would add to the dengue risk this year-end," the agency said.

NEA urged the public to continue following preventive measures, such as the five-step "mozzie wipeout", in order to prevent mosquito breeding. The five steps are: break up hardened soil, empty flowerpot plates, overturn pails and wipe their rims, change water in vases, and keep roof gutters clear and place insecticide inside.

The agency said it conducted about 523,000 mosquito breeding inspections from January to September this year and found about 14,300 mosquito breeding habitats.

It said: "During the same period, more than 5,500 enforcement actions were taken against premises owners for mosquito breeding."

The agency advised residents, especially those living in dengue cluster areas, to carry out three protective actions against dengue - spray insecticide in dark corners around the house, apply insect repellent regularly, and wear long-sleeved tops and long pants.

Households can be fined $200 to $400 for mosquito breeding. Repeat offenders can be hauled to court, where they face a fine of up to $5,000, three months' jail, or both.

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