Japan is seeing signs of a national mumps epidemic for the first time in 4 1/2 years, statistics compiled by the National Institute of Infectious Diseases (NIID) show.
The mumps spreads predominantly among children, and experts are calling for enhanced preventive measures, urging people to get vaccinations and wash their hands.
The mumps is caused by infection with the mumps virus, and has a relatively long incubation period of two to three weeks. It results in swelling under the ears and chin and a fever. Normally the disease heals naturally within about two weeks, but complications such as meningitis can occur, and in about 1 in every 1,000 cases, the disease results in hearing loss and other problems.
In recent years, epidemics have occurred in cycles of four or five years, but the exact reasons behind this cycle remain unclear.
Between Jan. 4 and 10, reports from about 3,000 providers of pediatric care showed there were 3,771 patients, or an average of about 1.2 per institution -- surpassing 1 for the first time since July 2011. In over 20 of Japan's 47 prefectures, the average was 1 or more per institution.
Four prefectures passed the warning level of an average of 3 cases per institution: Saga (5.00), Miyazaki (4.23), Ishikawa (3.31), and Okinawa (3.21). In eastern Japan, Yamagata Prefecture had an average of 2.50, while Chiba Prefecture marked a figure of 1.77
Tomimasa Sunagawa, of NIID's Infectious Disease Surveillance Center, commented, "The number of reported cases at this time of the year is the third-highest we've seen in the past 10 years. In years when the disease is prevalent, cases tend to increase from the winter to the summer, and a national epidemic is feared. In addition to washing one's hands, there are effective vaccines, and we ask people to take proper countermeasures."