GEIS-新闻详情

Dengue cases highest in over a year, but recent storms may bring relief

2024-01-19 00:00:00.0 海峡时报-新加坡原网页

SINGAPORE – Dengue infections have been going up for six consecutive weeks, with 396 cases reported in the week of Jan 7 to 13 – the highest weekly figure in more than a year. Six weeks ago, there were just 143 cases.

While this is a far cry from the 1,552 cases a week at the peak of the infection in 2022, the steady increase in cases has the National Environment Agency (NEA) urging people living in dengue cluster areas to take immediate action to suppress the Aedes mosquito population and help break disease transmission.

It also asked them to cooperate with NEA officers inspecting their property for mosquito larvae.

There were almost 10,000 dengue cases reported in 2023, down from the more than 32,000 cases in 2022. The largest number of this Aedes mosquito-borne viral infection seen here was in 2020, when there were 35,315 cases and 32 deaths.

Dengue caused three deaths here in the first nine months of 2023. In 2022, 19 people died.

However, experts say the recent storms could lead to a drop in dengue cases.

“The general trend is for dengue cases to dip after heavy rainfall and this dip can go on for as much as six weeks,” said Professor Hsu Li Yang, an infectious diseases expert and vice-dean for global health at the National University of Singapore Saw Swee Hock School of Public Health.

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While wet weather resulting in standing water increases mosquito breeding, heavy rain causes a “flushing effect” where the larvae are washed away, killing most of them.

The experts are also not overly worried about the two changes in the dominant dengue serotype in 2023, although they warn that a second infection could prove more serious.

There are four dengue serotypes. DEN-3, the dominant strain behind the bulk of infections in 2021 and 2022, was overtaken by DEN-1 in June 2023, and later DEN-2 in September.

People do not get reinfected by the virus from the same serotype, but can be infected by the other three strains.

Professor Paul Tambyah, president of the United States-based International Society for Infectious Diseases, said the switch in dengue serotype is unlikely to result in a higher number of infections, although it may be too early to be sure.

“There was concern (back in 2021) that DEN-3 had not been circulating for some time and thus immunity levels would be low,” he said.

“DEN-2, on the other hand, has been circulating almost continuously for decades. And thus, this year’s peak may be lower than previously, like last year’s, when DEN-1 was dominant during the mid-year season,” said Prof Tambyah, who is also a senior consultant in infectious diseases at the National University Hospital.