The number of conjunctivitis cases increased by 120,000, Wednesday to total 280,000 in 5,974 schools nationwide, more than half of the country's 10,000 elementary and secondary schools. The number of schools closed also increased to 141.

The eye infection has also affected China since mid August focused on the provinces with concentrated rainstorms, including Guangdongsheng and Hunan.

The viral eye infection is also called "Apollo disease" as it spread worldwide at the time when the spacecraft Apollo 11 landed on the moon in 1969. It is cyclic in nature and epidemics recur every five to ten years. (Kim Su-hye, goodluck@chosun.com )