Photo/Illutration The group A streptococcus (Provided by National Institute of Infectious Diseases)

A record number of cases of a potentially fatal “flesh-eating disease” were reported in Japan in 2023, and health experts warn the figure could rise.

The number of patients diagnosed with streptococcal toxic shock syndrome (STSS) had decreased during the COVID-19 pandemic, but confirmed cases surged to 941 last year, topping the previous record of 894 set in 2019, according to the National Institute of Infectious Diseases (NIID).

An estimated 30 percent of STSS cases end in death because symptoms can suddenly worsen.

There are concerns the disease will spread further in Japan because strains that have high virulence and infectivity have been confirmed here.

The health ministry on Jan. 17 asked local governments to analyze samples taken from STSS patients to determine the strains.

STSS is mainly caused by a bacterium called streptococcus pyogenes, better known as group A streptococcus, which is known to bring on strep throat mainly among children.

In some cases, an infection can turn deadly, especially among adults over 30. Most patients who come down with STSS are senior citizens.

The initial symptoms of STSS are sore throat, fever, diarrhea, vomiting and lethargy.

But some patients have died within dozens of hours due to multiple organ failure or breathing problems.

The bacterium is called flesh-eating because it causes necrosis of a band of tissue that surrounds the muscles of patients.

The bacterium often enters the bloodstream and spinal fluid where bacteria cannot normally be detected. That leads to a sudden decrease in functioning of many organs.

STSS can be caused not only by group A streptococcus but also by the group G strain.

According to the NIID, the group A strain leads to more fatalities among those under 50. Sixty-five patients under 50 were diagnosed with STSS between July and December 2023. About one-third of them, or 21, died.

Although the infection process is still not known, the bacterium has been known to infect patients through wounds on the hands and feet.

“There are many things we do not know, such as why the bacterium becomes fulminant,” said Takashi Nakano, a professor of infectious diseases at Kawasaki Medical School. “Normal measures to prevent infectious diseases, such as washing hands and keeping a wound clean, should be taken.”

He added that immediate medical treatment should be started if the symptoms seem different from normal.

He suggests visiting a medical institution if a wound begins to swell or becomes painful, and if other symptoms of infection, such as a fever, appear.

The highly virulent and infectious UK strain of the bacterium, the main one in the West, has been confirmed in Japan. Nine cases of the UK strain have been found within the same Japanese prefecture since August.

(This article was written by Mirei Jinguji and Kazuya Goto.)

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