As rising temperatures expand the habitat of the dengue-carrying tiger mosquito across northern Japan, one expert is urging authorities to take steps to curb the viral disease, which may have returned to the country after a 60-year absence.
In 2010, around 240 people were infected with the disease, which causes fever and joint pain, while traveling overseas, but no domestic infection has been confirmed in six decades.
However, it is likely that a German woman contracted dengue in January while traveling in Japan, according to the expert.
Research by Mutsuo Kobayashi, honorary member of the National Institute of Infectious Diseases, confirmed the presence of tiger mosquitoes across Miyagi Prefecture and parts of Akita Prefecture in 2000. The insects are predicted to reach Hokkaido at the end of this century.
"The rise in temperature in northeastern Japan during the past 10 years is amazing," Kobayashi said. "It has been a change that should usually be observed over several hundreds of years."
While habit expansion does not necessarily guarantee an epidemic, the mosquitoes could transmit the virus if a carrier exposes them to it.
"Japan has become a country with the risk of dengue fever," Kobayashi said, suggesting he expects domestic infections to increase.
The Health, Labor and Welfare Ministry has called on prefectural governments to immediately report patients who they believe have developed dengue fever.