Monday, June 04, 2007

Straits Times (2 June 2007) - Dengue Strikes

Straits Times - 2 June 2007:
June 2, 2007

Scientists stumped by 2 dengue findings here
Strains of disease found here and victims differ from elsewhere in region
By Tania Tan
UNDER INVESTIGATION: Health Minister Khaw Boon Wan visited Sembawang Drug Rehabilitation Centre to review the situation there. -- CHEW SENG KIM
SCIENTISTS studying dengue fever here are stumped on two fronts - that uniquely Singapore strains seem to have risen here and that young adults are most hit by the fever.
Early results from an ongoing islandwide study show that the strains of the virus circulating here could be evolving differently from those in other parts of the region.
Dr Martin Hibberd, a dengue researcher and associate director of infectious diseases at the Genome Institute of Singapore, said: 'It's possible that almost all the strains we see now are found exclusively in Singapore.'
Preliminary findings of the Early Dengue (Eden) infection and outcome study also suggest that young adults here - those over 21 - are more often victims of the disease than their counterparts in other Asian countries where the disease is endemic.
In Indonesia and India, for example, dengue victims are much younger - children.
In the region, the chance of meeting an infected Aedes mosquito carrying the virus is once every six months.
Dengue strikes
Here - because of stringent vector control - the chance of getting bitten by an infected mosquito is about once every 10 years, what Dr Hibberd calls 'a statistical rarity'.
Adults are therefore more likely to be bitten - simply because they have been around longer.
But dengue infection in adults is not well studied here. Instead, most records are of cases of infection among children, said Dr Hibberd.
Even guidelines on treatment and management of the disease from the World Health Organisation were developed with young patients.
With so little to fall back on, doctors and scientists here have their work cut out. They have therefore pulled out all the stops in this fight against disease-bearing mosquitoes.
Eden, launched in 2005, is a collaboration between the Novartis Institute for Tropical Diseases, Tan Tock Seng Hospital and the National University of Singapore (NUS).
The study, which tracks the progress of disease development in volunteer patients with fever, hopes to shed light on how adult immune systems respond to dengue, and how best to treat the disease.
Another islandwide study by the National Environment Agency is investigating the proportion of people with immunity against different types of dengue.
Because not enough is known about the disease, vaccines are difficult to develop.
Some drugs are already in clinical trial phase, but researchers have yet to strike upon the 'perfect' vaccine, even after 20 years, said a Novartis spokesman.
A key hindrance is the fact that there are four types of dengue.
Vaccines that do not protect against all four types could do more harm than good, in that patients could end up developing more severe symptoms, said Associate Professor Paul Ananth Tambyah from NUS' Yong Loo Lin School of Medicine.
'That is a very high standard that most modern vaccines cannot meet,' he said.


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