Cases of mycoplasma pneumonia in Japan have marked a record high for the third straight week.
Mycoplasma pneumonia is a respiratory disease caused by bacteria. Children are more likely to become infected.
It spreads through water droplets and physical contact, and symptoms include fever, fatigue, headaches and coughing.
Coughs can last for more than a week, with some patients requiring hospitalization due to severe pneumonia or physical weakness.
Data from the National Institute of Infectious Diseases show that the average number of cases reported by about 500 medical institutions nationwide was 1.95 per institution in the week through October 13.
The figure has increased for seven consecutive weeks and is the highest since the current method of record keeping began in 1999.
Fukui Prefecture had an average 5.67 patients per institution, followed by Aichi at 5 and Kyoto at 4.29.
Professor Oishi Tomohiro of Kawasaki Medical School says patient numbers will likely remain high as the disease spreads more easily in winter.
He urges people to wear surgical masks in schools and other places with regular human contact to help prevent infection.