A mosquito-borne illness that can permanently deform a person’s joints was confirmed in four Japanese patients in June and July, the National Institute of Infectious Diseases warns.
Developing within two to 12 days of a mosquito bite, symptoms of the disease, Chikungunya fever, which is mainly prevalent in Asia and Africa, include fever and joint inflammation. The mortality rate is low, but joint pain can last for several months and result in deformities.
The four detected with the virus have a history of traveling overseas to such places as Papua New Guinea and Cambodia, according to the institute.
This year’s high incidence rate over a short period is rare, given only about 30 cases have been reported since 2006.
The disease can be transmitted by the Asian tiger mosquito, a variety found across the country except in Hokkaido.
The institute says the mosquito poses a danger of spreading the disease within Japan, although cases so far concern travelers who most likely caught it overseas.
“If more people contract it, mosquitoes could proliferate the virus,” said an official at the institute. “Though no signs have been detected that it is spreading domestically.”