Experts Call For New Ways To Tackle Dengue In Singapore

SINGAPORE, Oct 1 (Bernama) -- Singapore's previous success in controlling dengue may have contributed to the ongoing outbreak of the disease in the republic, according to a finding by a panel of expert formed to advise the government on ways to tackle the problem.
"The success of the Singapore programme has reduced the Aedes aegypti (the mosquito which transmits the disease) population to such a low level that conventional methods of assessing populations such as the house index are no longer sufficient.
"Moreover, an increase in the Aedes population is not always a pre-requisite for increased dengue transmission," Clinical Professor and Assistant Chief Executive Officer of National Healthcare Group Dr Chee Yam Cheng told a press conference.
Dr Chee chairs the panel comprising seven members from local and international institutions whose job is to advise the government on ways to tackle the outbreak that has left the authorities baffled on why Singapore, a highly health conscious nation, has to deal with the disease that is more associated with filthy surroundings.
Twelve people had died of the disease from about 11,000 cases reported this year -- a record high.
The panel agreed that Singapore's dengue control programme is one of the best in the world, which has resulted "in sustained suppression of the Aedes aegypti mosquitoes for three decades".
But Dr Chee said: "Aedes is highly adaptable and exploits hard-to-find habitats in the urban environment. The increase in the dengue cases in Singapore may include importation of new strains of dengue virus with greater epidemic potential into a densely populated Singapore population".
He also said that Singapore's prior success in dengue control programme "has resulted in a highly susceptible human population".
The panel acknowledged that the problem was not unique to Singapore.
"Dengue is a resurgent problem globally; and being endemic to the region, Singapore can expect dengue to recur on a regular basis. The current dengue outbreak in Singapore coincides with the increase in the number of dengue cases in the region," Dr Chee said, adding that public education on dengue prevention and community participation in control activities remained the key to stop dengue transmission.

The panel recommended a host of short-and-long-term measures to deal with the problem including the need for an "active laboratory-based disease surveillance programme to provide early warning for epidemic transmission".
"Laboratory methods should include the latest technology in both serologic and virologic diagnosis. Quality control for this programme should be provided by a national reference laboratory for infectious diseases," Dr Chee said.
A continuing medical education programme should be implemented to increase the knowledge of physicians on clinical diagnosis, management, prevention and control.
"It is a common perception that most dengue transmission occurs at home. However, recent epidemiologic evidence indicates that significant transmission also occurs at sites away from the home. Current emphasis on active clusters does not provide an adequate understanding of transmission dynamics.
"This limits the effectiveness of vector control measures, because in the present situation, it appears that 60 to 70 per cent of all notifications occur outside of known clusters and in some instances transmission is not reported," Dr Chee said.
Emphasis should now be placed on new and innovative methods of entomologic surveillance to assess the impact of control activities on Aedes populations, he said.
Mosquito control activities, including those by private pest control operators, must continue to be subjected to stringent and improved quality control measures using new techniques, he said.
Long-term measures include: to maintain Aedes populations at a low level that will prevent epidemic dengue transmission, to use vaccines and antiviral drugs when they become available and to use new validated technologies as they become available.
The quarantine of dengue patients is not recommended, he said.
"Infected people can infect mosquitoes with dengue viruses 24 to 48 hours before showing any symptoms. Infected people, who do not show any symptoms may also infect mosquitoes. With Singaporeans being highly mobile and the local dispersal of mosquitoes, the virus may be widespread in the community before it is reported," he said.