Japan’s health authorities have declared a nationwide influenza epidemic after surveillance showed an abrupt and unusually early surge in cases that began in late September. Japan’s Ministry of Health, Labour and Welfare (MHLW) reported 6,013 influenza cases from about 3,000 designated medical institutions as of October 10, an average of two patients per institution, exceeding the official epidemic threshold of 1.00.
Several prefectures reported much higher local intensity, with Okinawa showing the highest per-institution count (12.18), while Tokyo was also among the worst-hit regions. According to a South China Morning Post report, schools and childcare centres have been especially affected.
Media and public-health summaries indicate that around 135 schools, kindergartens, and childcare facilities were closed across multiple prefectures in the past two weeks, about three times more than at the same time last year. Closures have been concentrated in Tokyo, Okinawa, and Kagoshima.
Flu vs common cold
Seasonal influenza (the flu) is an infection caused by any of the four types of influenza viruses A, B, C, and D, with influenza A and B causing the most common seasonal outbreaks in humans. Symptoms of influenza include acute onset of fever, cough, sore throat, body aches and fatigue.
The flu and the common cold share many similar symptoms. However, the common cold can be caused by several different viruses, including rhinoviruses, according to the US Centres for Disease Control and Prevention (CDC).
Influenza cases are typically higher between December and March and between May and August, according to Singapore’s Communicable Diseases Agency. Meanwhile, the World Health Organisation (WHO) says that in temperate climates, seasonal epidemics occur mainly during winter, while in tropical regions, influenza may occur throughout the year, causing outbreaks more irregularly.
Why are influenza cases more frequent now?
Experts warned that the virus may be evolving faster and spreading more easily or earlier than typical in some regions. Moreover, an early and rapid spread suggests the influenza virus is adapting at an unprecedented pace. Emerging research indicates the virus is not only spreading more efficiently but may also be developing resistance to conventional treatments.
