Kumamoto City is urging caution about Dengue fever. Don’t be too alarmed, however; there is no outbreak at the moment. Last year, however, many cases were reported in the Tokyo area. The city is urging caution in an attempt to preempt a sudden outbreak. They recommend that we all minimize our exposure to mosquitos and to avoid creating conditions in which mosquitos can breed easily.
Here’s a link to a Shisei Dayori item about the issue:
http://www.kumamoto-if.or.jp/topics/topics_detail.asp?PageID=5&ID=7974&pg=1&sort=0&LC=e
The following link is to a news article about the situation in Japan in general: