Southeast Asian nations are battling a surge in dengue cases, amid signs that climate change could make 2007 the worst year on record for a disease that often gets less attention than some higher-profile health risks.

The spread of dengue, which is transmitted by the Aedes aegypti mosquito and is endemic in much of the region, has also accelerated in recent years due to increasing urbanization and travel or migration within the region, experts say.

Efforts to develop a vaccine are proving difficult because dengue can be caused by four viruses. So the only real method to fight the disease at present is to eliminate likely breeding spots for mosquitoes from discarded tyres to plant pots.

"The threat of dengue is increasing because of global warming, mosquitoes are becoming more active year by year and their geographical reach is expanding both north and south of the Equator," said Lo Wing-lok, an expert in infectious diseases.

"Even Singapore, which is so affluent and modern, can't exercise adequate control," Hong Kong-based Lo added.

Dengue cases in Hong Kong usually involve people returning from hotter parts of Asia, but Lo warned that warmer temperatures meant the disease could ultimately become endemic in southern China.

Dengue sufferers often describe the onset of high fever, nausea and intense joint pain. There is no real treatment, apart from rest and rehydration, and in severe cases it can be fatal.

In Indonesia, where concerns over bird flu more frequently grab headlines, dengue saw a dramatic peak earlier this year after much of the Jakarta area was flooded.

"It's not so much the rise in temperature that affects dengue, rather the rising rainfall has lengthened the lifespan of the epidemic each season," said Wiku Adisasmito, a dengue expert at the University of Indonesia.

The Asian Development Bank developed a model suggesting that dengue might rise three-fold in Indonesia due to climate change.

By last month there had been 68,636 cases and 748 deaths so far this year, according to Health Ministry data.

Although cases are slowing at the end of the wet season, experts warn that 2006's record 106,425 cases could easily be overtaken. The record number of deaths was 1,298 in 2005.


The picture looks similar in neighboring countries.

Thailand had more than 11,000 cases of dengue fever and 14 deaths by this month, up 18 percent from the same period of 2006.

In May, the worst month, 3,649 people were found with dengue.

Most patients were between 10-24 years old, Deputy Public Health Minister Morakot Kornkasem said in a statement.

The number of dengue cases in Singapore last month was nearly three times that in the same period a year ago, according to the government, which says warmer weather was partly to blame.

The surge in cases has prompted the government to step up its anti-dengue campaign, urging Singaporeans to clear roofs and gutters, and throw out stale water in containers.

Between May 20 and 26, there were 259 dengue cases according to the Straits Times newspaper, the highest weekly figure this year, but below the weekly record of 714 cases in September 2005.

In Malaysia, 48 people died from dengue during the first five months of the year, health officials said, up roughly 71 percent from 2006. By May 26, 20,658 people had caught the disease, a surge of 55 percent over the corresponding 2006 figure.

"We are concerned over the increase and we need everyone to cooperate with the authorities to fight the menace," Health Ministry official Hasan Abdul Rahman told the New Straits Times recently.

Prevailing weather patterns of hot days punctuated by a day of rain have worsened the problem.

"There is no medicine to cure dengue fever, so the only treatment is to have a lot of electrolytes," said Noranita Badrun, a Kuala Lumpur resident whose daughter, Nurin Syakilah, spent a week in hospital in April battling the disease.

If not diagnosed early, dengue can kill, but Nurin, who received 18 bottles of intravenous fluids during her hospital stay, recovered soon and is back at school, where two other students also had the disease, Noranita said.