EPIDEMIOLOGICAL ASPECTS OF IMPORTED CHIKUNGUNYA FEVER AMONG OVERSEAS TRAVELERS IN JAPAN AND KOREA, 2013-2020
Myeong-Jin Lee* and Won-Chang Lee
Chikungunya fever is a viral infectious disease. Japan and Korea are not epidemic regions for chikungunya; however, infections among overseas travelers are increasingly being reported. In the present study, we investigated the epidemiological status of imported chikungunya fever cases in Japan and Korea during 2013–2020 and compared their characteristics. Raw data of chikungunya fever cases in Japan were obtained from the National Institute of Infectious Diseases website and those in Korea were obtained from the Korea Center for Disease Control and Prevention website. During the study period, 122 cases of chikungunya fever were reported in Japan, with average annual incidence of 0.94/1,000,000 overseas travelers; 40 cases were reported in Korea, with average annual incidence of 0.23/1,000,000 overseas travelers; Japan had a 4.1-times higher incidence than Korea. Most imported infections in both countries were acquired in Asia, with Myanmar the main source of infection in both countries. Japan had 1.5 times more Myanmar-originated cases than Korea (27.0% and 17.5%, respectively). In 2019, the first epidemic in 9 years occurred in Myanmar, leading to 32 Japanese and 7 Korean chikungunya cases (65.3% and 43.8% of annual cases, respectively). If travelers heading to Myanmar had received appropriate warning, these infections might have been prevented. The seasonal distribution showed a similar pattern in both countries; summer and autumn, especially September, were high-risk seasons. Owing to these situations, systematic improvements are needed in both Japan and Korea to provide timely and appropriate information about the risks and preventive measures against chikungunya fever for individuals who travel to high-risk areas during high-risk seasons.
Keywords: Chikungunya fever; Imported infection; Overseas travelers; Japan; Korea.
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