SINGAPORE - Dengue cases in Singapore soared to an eight-year high as 2013 came to a close on Tuesday, with more than 22,000 cases reported than in 2005.
The new peak is also an annual rise of nearly five times that of 2012.
Many parts of Singapore were hit hard, becoming high-risk red zones. Initially, these were in the eastern part of the island. By June, red clusters had popped up in the northern and western parts and, in October, Orchard Road became a red zone.
Currently, there are five red zones: Balestier, Yishun, Geylang, Lakeside and part of Serangoon. The worst is in Balestier, with 72 cases.
In all, Singapore has 48 active dengue clusters, where at least two cases are reported within 150m of each other in a fortnight.
Dengue, spread by the Aedes mosquito, can be deadly. Seven people died from it last year, compared with 25 in 2005.
But the 2005 strain is different from the DEN-1, currently the most common among the four strains in Singapore.
The DEN-1 can replicate inside mosquitoes at three times the speed of previous strains, which means the virus has higher epidemic potential.
People bitten by an infected mosquito usually develop a fever four to seven days later and suffer such symptoms as severe headache, muscle pain, nausea and rashes.
Typically, dengue peaks from June to August, after which the number of new cases will decline as the weather gets cooler.
The latest figures show that more than 400 people came down with dengue fever last week, with another 124 cases since Sunday.
In fact, the average number of weekly infections last month fell by more than half from the peak in June when it topped 800.
But the 2013 dengue pattern was "unusual", said Dr Ng Lee Ching, director of the National Environment Agency's Environmental Health Institute.
It may be due to "the high epidemic potential of the virus and also our low herd immunity", she said.
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