Weekly number of dengue cases in Singapore surpasses ‘historical high’

Weekly number of dengue cases in Singapore surpasses ‘historical high’

An Aedes Aegypti mosquito on human skin
An Aedes Aegypti mosquito on human skin. (File photo: AFP/LUIS ROBAYO)

SINGAPORE: The weekly number of dengue cases in Singapore has surpassed the record high reported in 2014, with 895 people infected in just five-and-a-half days.

That brings the total number of dengue cases in Singapore in 2020 so far to 10,732, according to data from the National Environment Agency (NEA).

The 895 cases were reported between Jun 7 and 3pm on Friday (Jun 12). NEA's weekly report of dengue cases takes into account infections diagnosed between Sundays and Saturdays, meaning the number of cases this week is likely to rise further.

At least 12 people have died from dengue this year, with the victims aged between 56 and 80.

With Singapore just entering the traditional dengue peak months - from June to October - the agency warned last week that the number of cases weekly could “exceed the historical high of 891” cases unless “urgent collective community action” is taken.

Singapore has also not seen such a high weekly number of cases since the peak years in 2013 and 2014, when the weekly cases hit a high of 840 and 891 respectively, NEA said on its website.

Dengue cases in 2013 to Jun 3, 2020
Graph showing the "historical high" of 891 dengue cases, recorded in 2014, and the peak of 840, recorded during Singapore's largest outbreak in 2013. (Graph: NEA)

READ: Spike in dengue cases: Why Singapore may see worst outbreak in years

The total number of cases in Singapore this year is expected to surpass the 15,998 cases recorded last year, and the 22,170 cases reported during the country’s worst outbreak in 2013, the agency said last week.

In the first four months of this year, the weekly number of cases hovered between 300 and 400, already high for those months.

But it surged to between 500 and 732 cases per week in May, and climbed above 800 in June. Last week, between May 31 and Jun 6, the country recorded 870 dengue cases.

As of Saturday, there were 210 active dengue clusters, of which 66 are deemed as "high-risk" by the agency.

These include a cluster of 207 cases in the Woodleigh Close area, 142 cases in the Potong Pasir Avenue 1, Avenue 2 and Avenue 3 areas, as well as 135 cases in the Tampines Avenue 7 area.

You can view the full list on NEA's website.

“The traditional dengue peak season could last for a few months, from June to October, thus immediate action must be taken to break disease transmission,” the agency said.

“NEA urgently seeks the community’s support to ensure that their homes (including common corridors where domestic items, such as potted plants and pails, are kept) and gardens in their compounds are free from mosquito breeding, and to use aerosol insecticide spray and mosquito repellent to protect themselves and their families.”

READ: How a vaccine made of mosquito spit could help stop the next epidemic

REASONS FOR DENGUE SURGE

The spike in early May coincided with Singapore’s COVID-19 "circuit breaker" period, NEA said. The Aedes aegypti mosquito, which spreads the dengue virus, dwells mainly in indoor spaces and bites primarily during the day.

With more people staying at home, this means more “blood meals” for the mosquitoes, especially in residential areas where the mosquito population is high.

There has also been a sharp rise in the number of mosquito breeding areas.

NEA officers observed a five-fold increase in the incidence of Aedes mosquito larvae detected in homes and common corridors in residential areas during the two-month circuit breaker, compared to the two months before. For construction sites, that figure doubled during the circuit breaker.

Singapore worker fumigates dogging mosquito dengue construction site
Workers wearing face masks fumigate a construction site to prevent the spread of dengue fever in Singapore on Apr 17, 2020. (Photo: AFP/Roslan Rahman)

The re-emergence of a less common dengue virus serotype - DENV-3 – is another factor for the rise in cases.

The serotype was last in a “dominant position” in Singapore about 30 years ago, which means there is low immunity in the population and a rapid disease transmission.

And as Singapore enters the traditional peak dengue season, the warmer weather is facilitating “faster multiplication” of the Aedes aegypti mosquito and the dengue virus, further increasing the chances of transmission.

READ: Trimming of green verges to be stepped up as measures ease after circuit breaker

WHAT YOU CAN DO

A majority of the dengue clusters are in residential areas. Residents are “strongly urged” to take steps to protect themselves and prevent mosquitoes from breeding.

This include spraying insecticide in dark corners of the home, such as under the sofa and bed or behind curtains and in toilets, NEA said.

Spatial mosquito repellents, such as mosquito coils, can also be used in well-ventilated areas of the home, and residents should consider using mosquito screens.

Last month, more than 300,000 bottles of mosquito repellent were issued to households in cluster areas. People should apply mosquito repellent to protect themselves from being bitten, the agency said.

People should also prevent potential mosquito breeding grounds. They should flip flower pot plates, tip vases, leave pails overturned or clear the roof gutter and drains within compounds.

Source: CNA/mi

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