Dengue fever is a mosquito-borne viral disease. Dengue virus (DENV)
infections occur in most of the tropical and subtropical areas of the world.
DENV infection with any of four serotypes leads to a broad spectrum of clinical
symptoms and their severity, including asymptomatic infection, dengue fever
(DF) and fatal dengue hemorrhagic fever (DHF). DF/DHF is considered to be
one of the most important re-emerging infectious diseases. Physicians and
pediatricians in non-endemic countries are often unfamiliar with the symptoms
and unaware of the potential importation of patients with DF/DHF. In August of
1942, an epidemic occurred suddenly in Nagasaki city and then in Sasebo city,
Osaka and Kobe city. The epidemic in 1942 was subsided in November, but in
the next summer it broke out again and recurred every summer until 1945.
There were no dengue endemics since 1945.
In late August of 2014, three autochthonous dengue cases were reported in
Japan. Since then, as of 31 October 2014, a total of 162 autochthonous cases
have been confirmed. While cases were reported from throughout Japan, the
majority was linked to visiting a large park or its vicinity in Tokyo, and the
serotype detected has been serotype 1.