A rare flesh-eating bacteria with a ‘terrifying’ mortality rate that can kill people in 48 hours is spreading in Japan

Cases of streptococcal toxic shock syndrome (STSS) reached 977 this year by June 2, higher than the record 941 cases reported for all of last year, according to the National Institute of Infectious Diseases, which has been tracking incidences of the disease since 1999. 

Group A Streptococcus (GAS) typically causes swelling and sore throat in children known as “strep throat,” but some types of the bacteria can lead to symptoms developing rapidly, including limb pain and swelling, fever, low blood pressure, that can be followed by necrosis, breathing problems, organ failure and death. People over 50 are more prone to the disease.

“Most of the deaths happen within 48 hours,” said Ken Kikuchi, a professor in infectious diseases at Tokyo Women’s Medical University. “As soon as a patient notices swelling in foot in the morning, it can expand to the knee by noon, and they can die within 48 hours.”

Other countries have experienced recent outbreaks. In late 2022 at least five European nations reported to the World Health Organization an increase in cases of invasive group A streptococcus (iGAS) disease, which includes STSS. The WHO said the rise in cases followed the end of Covid restrictions.

At the current rate of infections, the number of cases in Japan could reach 2,500 this year, with a “terrifying” mortality rate of 30%, Kikuchi said.

Kikuchi urged people to maintain hand hygiene and to treat any open wounds. He said patients may carry GAS in their intestines, which could contaminate hands through feces.