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Mosquito-Borne Diseases Infect Thousands in Asia

Health authorities in Asia report expanding outbreaks of potentially deadly mosquito-borne diseases. Thousands have contracted Japanese encephalitis and dengue fever in recent months.

Singapore is waging an $18 million, house-to-house battle to contain a dengue fever outbreak.

Hundreds of health officers are scouring potential mosquito breeding grounds on the island to stop the spread of the disease, which as of last week's count, has infected nearly 10,000 people, already topping the number of cases for all of last year. At least eight have died.

In the Philippines, dengue fever has killed at least 200 people this year. Cases were up 19 percent as of August.

Mosquitoes also are wreaking havoc in the northern Indian state of Uttar Pradesh, where an outbreak of Japanese encephalitis has killed more than 700 people, mostly children, and infected 3,000 since July.

In neighboring Nepal, Japanese encephalitis has reportedly killed more than 200 people in the past two months.

Outbreaks of both diseases occur often in Asia. But, this year, the caseload is surging.

Dr. Kevin Palmer, a dengue specialist at the World Health Organization office in Manila, says people become complacent about controlling mosquitoes, which breed in stagnant water.

"It's like a three- to five-year cycle. Between the cycle, people forget," said Dr. Palmer. "They start collecting containers in their houses, on their balconies, or something, and all you need is a year with a good combination of the right temperatures and right amount of rainfall, and, bang, you've got an outbreak," he said.

The outbreak in Singapore has baffled experts. The wealthy nation has long had a stringent anti-mosquito campaign, fining residents found with pools of stagnant water around their homes.

Dengue causes high fever and intense joint pain, and severe cases can lead to death. There is no vaccine.

Unlike dengue, there is a vaccine for Japanese encephalitis, which attacks the membranes around the brain. But the vaccine may be too costly for the poor. The fatality rate reaches 60 percent, and a third of the survivors may suffer nervous system damage.

In impoverished Uttar Pradesh state, hospitals have been struggling to cope with Japanese encephalitis. Authorities say a lack of vaccines, medicines and respirators hampers their efforts.

Public health experts say mosquito-borne diseases fall low on the priority list of poor governments in Asia, although they are easily prevented with mosquito nets and sprays, and by controlling breeding.

Experts are also urging changes at Asian farms where pigs and humans live close to each other, increasing the risk of Japanese encephalitis. Pigs carry the disease, and mosquitoes transmit it from the animals to humans.

The World Health Organization (WHO) says Japanese encephalitis kills about 15,000 people each year in Asia.