[The first case report of Ross River virus disease in a Japanese patient who returned from Australia].

A 31-year-old Japanese female had stayed in Australia from January to May 2013. She presented with a sudden onset of left ankle and right knee arthralgia in March but neither fever nor rash was present. As her arthralgia persisted, she visited our hospital upon her return to Japan in May. When she came to our hospital, she complained of left ankle and right knee pain, but no arthritis findings. Laboratory findings were also within normal ranges. Ross River virus (RRV) antibody levels were examined as she was suspected of having contracted the disease in Australia. RRV IgG antibody and IgM antibody were positive, and the patient was confirmed as a case of acute RRV disease. RRV disease is endemic in Australia, but there are no prior reports of the disease in Japan. This is the first case of RRV disease confirmed in Japan. Typical symptoms of RRV disease include arthralgia, fever, and rash. Our patient had only arthralgia. With the increase in the number of travelers and length of stay in RRV endemic regions, health care providers need to consider the disease in their differential diagnosis, among returning travelers with arthralgia, fever, rash and a travel history to RRV-endemic regions.