By North Asia correspondent Matthew Carney
Experts fear Japan’s first dengue outbreak since World War II could be a sign that global warming is helping the virus to spread to more countries.
The World Health Organisation said half the world’s population was now at risk of the mosquito-borne disease.
Over 70 cases of dengue have now been confirmed in Japan, with nearly all the cases tracked to Yoyogi Park, in the middle of Tokyo.
The park, which provides welcome relief to the 5 million visitors it gets every year has been closed for months, and the homeless community that shelters there had to move out.
“I’m surprised it’s happened,” said Sho Sato, who lived in the park for more than 12 years.
“Unless we kill all the mosquitoes, it’s just going to spread.”
Authorities have sprayed hundreds of litres of pesticides, drained all the ponds and lakes, and fenced off the park to try and contain the disease.
The director of Tokyo’s government health department, Keiichi Nakaya, said they have trapped and analysed about 300 mosquitoes.
“We’ve inspected the mosquitoes caught in Yoyogi park, and found the dengue virus in mosquitoes in four out of the ten locations we trapped them in,” he said.
Experts say the virus was most likely imported into the country by an infected individual who then transmitted it to domestic mosquitoes.
“We’re not sure it the patient is Japanese or a foreigner,” said Mutsuo Kobayashi, from the National Institute of Infectious Diseases.
“But we believe a Japanese mosquito sucked that person’s blood at Yoyogi Park, and then went on to breed and bite others in the park.”
The symptoms of dengue fever are severe joint and muscle aches, headaches and fever.
At this stage none of the 70 victims have become seriously ill, but in a worrying development, two more cases have been confirmed at another park in Tokyo.
At a recent conference, the WHO concluded that dengue fever was extremely sensitive to climate change, and expected the disease to spread dramatically, as it has done in the last couple of decades.
It estimates up to 100 million are infected annually. L
ast year, Singapore had an epidemic that saw four people die and 12,000 become infected.
Mutsuo Kobayashi from the Institute of Infectious Diseases expects Japan to experience more outbreaks in the future.
“The range of the Japanese mosquitoes which transmit Dengue is already spreading to the northern part of Japan,” he said.
“So areas at risk are increasing, and we believe this is caused by global warming.”