Dengue cases at 16-year low

The number of dengue infections in Singapore this year is the lowest in 16 years.
The number of dengue infections in Singapore this year is the lowest in 16 years.PHOTO: ST FILE

2,629 cases in first 50 weeks a drop of 10,000 from last year; but danger of flare-up remains

The number of dengue infections in Singapore this year is the lowest in 16 years, with no deaths from the disease in the first nine months.

In the first 50 weeks of the year, 2,629 people had dengue - a drop of more than 10,000 from the same period last year.

Though there are still two weeks until the end of the year, the total number of infections for this year is likely to be lower than in any year since the 2,372 cases in 2001.

The drop is in stark contrast to the 13,100 people infected last year - and the all-time high of more than 22,000 infections in 2013.

No one died of dengue in the January to September period this year.

Last year, nine people died, including an 11-year-old boy.

Generally, one in five people with dengue needs hospital care.

But the drop in infections is not due to better control of mosquito breeding. In fact, the National Environment Agency has said it is catching more Aedes mosquitoes under its surveillance system.

A spokesman for the agency said that this suggests "an increased number of the mosquito vector in our community".

She added that the low number of infections this year is probably because the dominant viral strain is DENV-2, against which many people here have immunity.

There are four dengue strains. Once someone has been infected, he is protected against that strain, but not the other three.

DENV-2 was also the dominant strain last year, as well as between 2007 and 2012.

As a result, many people previously infected with this strain are now immune to it.

The spokesman warned that despite the huge drop in infections this year, the danger of the disease flaring up again remains.

"Dengue transmission is a complex interplay of many factors, such as the mosquito population, virus type, human immunity and environmental parameters such as temperature, rainfall and humidity," she said.

With so many factors that cannot be controlled, efforts must continue to keep the mosquito population down, since it is through mosquito bites that the virus is transmitted, said the spokesman.

The last quarterly surveillance data also showed a drop in DENV-2 infections - from 69 per cent of all infections in August to 38 per cent in September.

A change in the dominant strain could lead to a surge in infections as fewer people might be immune.

There are now four active dengue clusters: two adjoining ones in Bedok Reservoir Road with a total of 62 cases, one in Toa Payoh Lorong 2 with three reported cases, and one in Tampines Street 21 with two infections.

A version of this article appeared in the print edition of The Straits Times on December 20, 2017, with the headline 'Dengue cases at 16-year low'. Print Edition | Subscribe