Dengue Fever Causing Alarm

By En-Lai Yeoh

SINGAPORE — The Philippines is stocking up on blood supplies, and Thailand is urging people to sleep under mosquito nets. An unusually severe outbreak of dengue fever has caused alarm across Asia and baffled clean, orderly Singapore with a record 10,000 cases this year.

The U.S. Centers for Diseases Control and Prevention considers dengue the “most important mosquito-borne viral disease affecting humans” this year — ahead of malaria and encephalitis — with an estimated 2.5 billion people at risk worldwide.

Across Asia, governments are scrambling to curtail the spread, mainly by educating the public about the potentially fatal illness and controlling mosquito-breeding areas such as stagnant pools.

Dengue is sometimes called bone-breaker’s disease because it causes severe joint pain. Other symptoms include high fever, nausea, and a rash. In the worst cases it causes internal bleeding. There is no known cure or vaccine.

While outbreaks are common in Asia, the latest has been unusually severe for reasons that remain unclear.

Dr. Kevin Palmer, a mosquito-borne diseases expert of the World Health Organization who is based in Manila, said Vietnam, Malaysia, Thailand and the Philippines all had a large number of dengue cases this year.

But Palmer is most perplexed by the spike in Singapore.

“It’s a city. It has a well-organized health care system and a preventive system,” he said. “It should kick it when it has an outbreak. There’s something missing when the cases go very high.”

Officials have compared the crisis to the 2003 severe acute respiratory syndrome outbreak that killed 33 here.

“It is baffling,” Singapore Health Minister Khaw Boon Wan said.

Hospitals have suspended non-emergency surgery to cope with the large number of dengue patients and health inspectors are searching public housing for mosquito-breeding areas. Soldiers are dousing their uniforms in a chemical mixture to ward off mosquitoes.

Yaacob Ibrahim, the minister in charge of a high-level committee on dengue, said authorities also were prepared to break into vacant properties to look for mosquito-breeding sites.

Dengue afflicts an estimated 50 million worldwide annually, according to the World Health Organization. Most cases are reported in Africa, Asia and South America. The disease is not spread by human-to-human contact, but rather by an Aedes mosquito that has bitten an infected person.

“It is largely a developing world’s disease,” said Dr. Subash Vasudevan, head of the dengue research unit at the Novartis Institute of Tropical Diseases in Singapore.

Thailand is advising people to eliminate sources of stagnant water around the home, to sleep under mosquito nets and to wear repellent, said Chaiporn Rojanawatsirivet of the Public Health Ministry.

The Philippine government has asked local authorities to intensify educational campaigns about dengue fever, organize mosquito-control systems, ensure sufficient blood supplies for transfusions and increase surveillance of cases.

Cases are down in Vietnam, but some central provinces are showing an increase because of drought that has forced villagers to keep water in open containers.