Global warming could bring tropical disease to northern Japan

Global warming could increase the chance of dengue fever breaking out in northernmost areas of Japan through an expansion in the habitat of the mosquitoes which transmit the virus, a recent study by the National Institute of Infectious Diseases shows.

Global warming could bring tropical disease to northern Japan
The disease, also known as breakbone fever, is usually a pandemic in Southeast Asia and other tropical areas, but it could occur even in Hokkaido, Japan's northernmost main island, by the end of this century when local temperatures are estimated to be high enough for the mosquitoes to thrive, a research group of the institute said.

The effect of global warming has brought on the fear of an expansion to the habitat of the tiger mosquito, which can transmit the dengue virus, further north in Japan to Hokkaido from the current limit in Akita Prefecture some 200 kilometers south of Hokkaido's southernmost tip, the group said.

Mutsuo Kobayashi, a member of the research group, said it is impossible to prevent the entry into Japan of the mosquitoes and the dengue patients. "It would be better for us to remove the mosquitoes," he said.

Tiger mosquitoes usually live in areas with an average annual temperature of 11 C or higher. The average in Hokkaido was 8.8 C in 2003.

In the 1950s in Japan, the northern limit of their living range was in Tochigi Prefecture, about 400 km south of Akita.

Rising temperatures as well as the development of commodity distribution systems have kept pushing the limit northward, the group said.

The research team estimated Japan's average temperatures in 2035 and 2100 based on the assumption that global warming will continue.

An average 50 million to 100 million people develop dengue fever every year in tropical and subtropical areas, with dozens of Japanese returning home with the virus after traveling in those regions.

Last Mod: 15 Eylül 2007, 10:51
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