In September of 2014, after an absence of more than 60 years, reports of locally acquired Dengue made big news in Japan, mostly linked to visits to popular Tokyo destination Yoyogi Park (once part of the 1964 Olympic Village), which is adjacent to the Harajuku railway station and Meiji Shrine in Shibuya.
Within a week of the first case, we saw Locally Acquired Dengue Cases Rise To 34, and by the end of October, the count had jumped to 160 (see EID Journal Autochthonous Dengue Fever, Tokyo, Japan, 2014).
Since the same mosquito vectors that transmit Dengue can also transmit Zika and Chikungunya, there are concerns over local introduction and transmission of those arboviruses as well.
With summer approaching, Tokyo has announced the start of expanded proactive monitoring of mosquitoes for arboviruses - including Zika - starting this week in Yoyogi and Ueno Park.
This from NHK World News.
The Tokyo Metropolitan Government has begun testing mosquitoes in the city's parks for the Zika and dengue viruses.
Tokyo started testing last year after reports of people being infected with the dengue virus while visiting parks. The tests were expanded this year to include the Zika virus, which has been prevalent in Latin America.
The field survey started in Yoyogi Park on Monday.
Workers used nets to catch mosquitoes around bushes. They also poured pesticides into ditches to prevent the breeding of mosquitoes.
The metropolitan government says it will conduct the survey twice every month at 9 parks and publish the results on its website.