A Retrospective Single-center Analysis of 16 Cases of Imported Chikungunya Fever in Japan.

Objective Chikungunya fever (CHIK) is a re-emerging arboviral disease that is transmitted through the bite of infected Aedes mosquitoes. There is limited information regarding the epidemiology and clinical information of imported CHIK in Japan. The objective of this study was to review the epidemiology and clinical information of imported CHIK patients treated at the National Center for Global Health and Medicine (NCGM). Methods We evaluated all patients (n=16) who were diagnosed with imported CHIK and treated at the NCGM between October 1, 2005 and March 31, 2016. Results The primary complaint of 7 patients who presented to the NCGM after 31 days from disease onset was persistent arthritis, and the primary complaints of 9 patients who presented within 30 days after disease onset were a fever, headache, arthralgia, and rash. Eleven patients experienced a rash during the first week of illness. The median duration of the arthralgia was 75 days, and the joint pain lasted for >2 months in 8 patients and >6 months in 3 patients. Persistent arthralgia was not significantly associated with an age of >35 years (p=0.13) or patient sex (p=0.69). All 16 patients exhibited positive results for CHIK IgM, although only 4 exhibited positive real-time polymerase chain reaction results. Conclusion Physicians should consider CHIK in patients with a fever who have returned from areas where CHIK is endemic.