Number of dengue cases last week is January record
LAST week's total of 544 new dengue cases is the highest recorded for the month of January, traditionally the low season for this viral disease.
The figure, released yesterday, was 96 up on the previous week, and the third weekly rise.
Leo Yee Sin, head of the Institute of Infectious Diseases and Epidemiology at Tan Tock Seng Hospital, called the pattern "rather unusual".
"The situation requires close monitoring and it is important for everyone to do their part in strengthening environmental prevention efforts," Professor Leo said.
The National Environment Agency (NEA) said the change of the main strain of virus from Den-1 to Den-2 - there are four strains of the virus - "may be an early indicator of a future dengue outbreak".
In 2014, four in five dengue patients were infected with the Den-1 strain. But Den-2 started rising from around August last year and now accounts for two in three infections.
In a joint statement to The Straits Times, NEA and the Ministry of Health said that although Den-2 was the dominant strain from 2007 to 2012, immunity in the population is low.
A study in 2013-14 found that less than 15 per cent of those aged 16 to 25 years were immune to Den-2.
Last month, NEA issued nine stop-work orders to construction sites found breeding mosquitoes.
None was in Tampines, which now has the biggest cluster with 206 cases, 33 within the past fortnight. There are currently 108 active dengue clusters, mostly in the eastern half of the country.