A record high 263 patients are suffering from streptococcal toxic shock-like syndrome (STSS), a deadly infection that causes necrosis in limbs and a consciousness disorder, as of mid-December, according to a survey that began in 1999.
The National Institute of Infectious Diseases (NIID) is calling on people to visit a doctor or a medical institution immediately after a possible STSS symptom is detected, such as a severe sore throat and swollen limbs.
According to a survey carried out by the NIID, a maximum of 100 patients suffered from the disease annually until 2010, but the figure soared to over 200 after 2012.
This year, that number reached 263 as of Dec. 14, topping the previous worst record of 242 in 2012.
By prefecture, Tokyo ranked first with 41, followed by Kanagawa with 19 and Aichi with 18.
The infection is mainly caused by Group A Streptococcus, which causes pharyngitis and impetigo in children.
It is believed to infect patients through the mucous membranes of the throat and other body parts, as well as open wounds, but details remain unclear.
It is unknown what triggers the disease.
The initial symptom includes a fever higher than 38 C and severe pain and swelling around wounds.
The condition may lead to a state of shock, multiple organ failure and other results in a few days.
Twenty people died from the disease last year, and early treatment using antibacterial drugs is essential.
It is also called "flesh-eating bacteria" as it may bring about necrosis in fascia tissues such as on limbs and the face.
"We ask people to avoid getting infected with STSS taking such measures as washing their hands every day," a NIID official said.
"They should seek immediate treatment at medical institutions should STSS symptoms appear."