On Jan 12, it reported a record 544 new dengue cases so far in January which is traditionally a low month for the disease.
NEA says 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 Den-1. 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, the NEA and the Ministry of Health (MOH) said that although Den-2 was the dominant strain from 2007 to 2012, immunity in the population is low. A 2013-2014 study found that less than 15 per cent of those aged between 16 and 25 were immune to Den-2.
Last month, the NEA issued nine stop-work orders to construction sites found breeding mosquitoes. However, 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.
Last year, more than 2,200 dengue patients were warded in public hospitals out of 11,298 people diagnosed with the disease. An MOH spokesman said this was in line with the norm of one in five dengue sufferers needing hospital care.
DOES VACCINE WORK?
A few countries, including the Philippines, have introduced the first available dengue vaccine. But Prof Leo said it might not be as effective in Singapore as it gives better protection against Den-3 and Den-4, which are not the dominant strains here. Singapore has a large adult population that has never had dengue. People who have been infected are protected against only that viral strain and not the other three.
More than 11,200 people were diagnosed with dengue in 2015, with four dying as a result. NEA officers carried out more than 1.4 million inspections last year and found 15,000 breeding spots.