Imported malaria and dengue fever in returned travelers in Japan from 2005 to 2010.

Malaria and dengue are important problems in Japan particularly since international travel to developing countries has become increasingly popular. To describe the clinical features of malaria and dengue cases in Japan, a retrospective study was conducted on 50 malaria cases and 40 dengue cases presented to the National Centre for Global Health and Medicine of Japan between 2005 and 2010. The most frequent area of acquisition for cases of malaria was Africa (76.0%), and for dengue fever was Asia (90.0%). Although the immigrant population is very small in Japan, patients categorized as visiting friends and relatives were relatively high in proportion, which is similar to Western reports. Confirmed cases of malaria and dengue account for less than 10% of the all travelers returning with any health problems according to the National Centre for Global Health and Medicine. Careful observation of symptoms and signs helps the differential diagnosis of malaria and dengue.