Korea's health authorities have raised the alarm for Japanese encephalitis.
The Korea Centers for Disease Control and Prevention issued a nationwide advisory on Tuesday after it spotted a species of mosquito that carry the virus in the southern city of Busan.
Most infections result in mild fever or no outward symptoms,... but according to the World Health Organization, one in 250 infections result in severe clinical illness,... and the fatality rate can be as high as 30 percent among those with disease symptoms.
Two people in Korea are known to have died from the virus last year.