Environmental Risks

Takatorige, Toshio; Hirose, Yukio; Nagamatsu, Shingo

Dengue fever is an infection caused by dengue virus carried by mosquitos, and it is a disease local to the tropics and subtropics regions, especially Southeast Asia, South Asia, Central and South America, and the Caribbean islands. The infection has recently been reported in Africa, Australia, China, and Taiwan. The estimate is about 100 million worldwide infections annually, and about 250,000 are affected with symptoms. Mosquitos cannot live through the winter in Japan with high latitude, and dengue fever is not a resident local here. Sporadic cases in Japan, however, are increasing where the patients had been infected overseas and showed symptoms after their return (imported case). The number of patients reported annually, excluding January to March, has been 9 in 1999 March, has been 9 in , 18 in 2000 March, has been 9 in , and 200 in 2010 In 2014, the number of patients and infected exceeded 150 cases among those that visited Yoyogi park in Tokyo. Global warming has pushed the habitat of Asian tiger mosquitos up north close to Aomori Prefecture, and the virus may turn into a resident one. We need to keep our eyes on this risk.