Matthew Carney reported this story on Monday, September 8, 2014 08:04:00

CHRIS UHLMANN: Japan is suffering its first outbreak of dengue fever since the Second War World.



Over 70 cases have now been confirmed.



Experts fear more countries will experience outbreaks as global warming causes the spread of the mosquitoes carrying the virus.



The World Health Organisation (WHO) says half the world's population is now at risk.



North Asia correspondent Matthew Carney reports.



MATTHEW CARNEY: Nearly all the cases of dengue fever in Japan have been tracked to Yoyogi Park.



It's a huge park in the middle of Tokyo, and provides welcome relief to the five million visitors it gets every year.



But now it's could be closed for months.



Twenty-eight year old Jun Hayashi used to go to the park daily.



JUN HAYASHI (translated): I come here to jog, and today I have guests, so I wanted to show them the Meji Shrine.



So it's sad and inconvenient it will be closed for a while.



MATTHEW CARNEY: The homeless community that shelters in the park has had to move out.



Sho Sato has lived there for more than 12 years.



SHO SATO (translated): I'm surprised it's happened. Unless we kill all the mosquitoes, it's just going to spread.



MATTHEW CARNEY: 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, says they've trapped and analysed about 300 mosquitoes.



KEIICHI NAKAYA (translated): We've inspected the mosquitoes caught in Yoyogi park, and found the Dengue Virus in mosquitoes in four out of the 10 locations we trapped them in.



MATTHEW CARNEY: Experts say the virus was most likely imported into the country by an infected individual who then transmitted it to domestic mosquitoes.



Mutsuo Kobayashi is from the National Institute of Infectious Diseases.



MUTSUO KOBAYASHI (translated): We're not sure it the patient is Japanese or a foreigner, 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.



MATTHEW CARNEY: At this stage none of the 70 victims have become seriously ill.



The symptoms of dengue fever are severe joint and muscle aches, headaches and fever.



But in a worrying development, two more cases have been confirmed at another park in Tokyo.



At a recent conference, the World Health Organization 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.



The World Health Organisation estimates up to 100 million are infected annually.



Last 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.



MUTSUO KOBAYASHI (translated): The range of the Japanese mosquitoes which transmit dengue is already spreading to the northern part of Japan, so areas at risk are increasing, and we believe this is caused by global warming.



MATTHEW CARNEY: This is Matthew Carney reporting from Tokyo for AM.