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

The number of patients with fulminant streptococcal toxic shock syndrome (STSS) has exceeded 1,000 since January, which can cause necrosis and has a high fatality rate.

This exceeds last year’s total, which was the highest number since 1999, when data first became available.

The outbreak currently has no end in sight.

According to the preliminary figures released by the National Institute of Infectious Diseases on June 18, this year's number of cases stood at 1,019 as of June 9.

In six months, the number has already surpassed last year’s 941 cases.

There are several strains of streptococcus, such as group A streptococcus and group B streptococcus.

Group A causes pharyngitis (strep throat), an epidemic that spreads mainly among children every winter and from spring to early summer. Severe cases are rare and it is a well-known pathogen.

However, if the bacteria enters the body through a wound, it can cause the much deadlier fulminant STSS. The "flesh-eating bacterium" can infect patients through wounds on the hands and feet, causing rapid necrosis and multiple organ failure. 

Death can occur within a few dozen hours of its onset; the fatality rate is an estimated 30 percent, which is considered extremely high.

Pharyngitis and STSS caused by group A streptococcus have been increasing since the second half of 2023.

According to the NIID, typically, more than 70 percent of patients with STSS are 50 or older. However, from July to December 2023, the percentage of patients under 50 increased.

Experts believe that the cause is the “M1UK strain,” a highly toxic and highly infectious strain of group A streptococcus.

Many cases caused by this strain have been reported in the U.K. and other countries since the 2010s.

Experts believe this particular strain entered Japan from overseas and suggested this a possible cause for its spread. 

“We don’t know the exact reason, but the number of patients with pharyngitis caused by streptococcus is increasing, and (that increase) is believed to be contributing to the increase in the number of STSS patients," said a health ministry representative.

The number of reports of STSS patients is also on the increase overseas.

Strep throat and similar symptoms are typically the only side effects of streptococcus, so the exact link between how it leads to STSS is unknown. 

The ministry has urged the public to take basic infection control measures such as washing one's hands, wearing a mask and keeping injuries clean.

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