A deadly outbreak of a “flesh-eating bacteria” is spreading rapidly across Japan, alarming health officials with how quickly it can lead to death.

Close to 1,000 cases of Streptococcal toxic shock syndrome (STSS) have been reported in the Asian country this year, and doctors warn symptoms can be fatal within 48 hours.

As of June 2, Japan reported 977 STSS cases, already surpassing last year’s total of 941 cases within the first six months of 2024, according to the country’s National Institute of Infectious Diseases.

Local newspaper Asahi Shimbun reports that the outbreak has hit Tokyo particularly hard, with 145 cases in the first half of this year already. The majority of cases have been reported in adults over 30, and the death rate is around 30 per cent.

The disease is a response to Group A Streptococcus (GAS), the same bacteria that causes strep throat in children. Some strains of the bacteria can lead to rapidly developing symptoms like fever, low blood pressure, limb pain and swelling. If untreated, these symptoms can develop into necrosis, organ failure, difficulty breathing and even death.

“Most of the deaths happen within 48 hours,” said Ken Kikuchi, a professor in infectious diseases at Tokyo Women’s Medical University, in an interview with Bloomberg. “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.”

Kikuchi warns that at this rate of infection, the number of cases in Japan could soar to more than 2,500 this year. Individuals over the age of 50 are particularly susceptible to severe disease and death, health officials warn.

Treatment for STSS involves high-dose IV antibiotics and supportive care, but prompt attention and intervention is crucial.

According to the National Institute of Infectious Diseases, the best protection against GAS and STSS is good hygiene, including thorough hand washing, treating any GAS infections promptly, and keeping a close eye on any wounds, cuts or infections of the skin.

The U.S. Centers for Disease Control (CDC) says “people with an open wound are at increased risk for STSS,” including those recovering from surgery and operations, as well as those with viral infections that cause open sores.

Earlier this year, the Public Health Agency of Canada revealed that invasive Group A Streptococcus (iGAS) disease activity was higher in 2023 compared to pre-pandemic years, and has been identified collectively by the federal, provincial and territorial governments as a priority for monitoring and control and must be reported to the public health authorities.

Around the world, other countries have also reported an uptick in both GAS and iGAS infections, post-pandemic. In late 2022, at least five European countries reported an increase in iGAS cases to the World Health Organization, coinciding with the lifting of COVID restrictions in each country.