A disease caused by a rare “flesh-eating bacteria” that can kill people within 48 hours is spreading in Japan. A total of 977 cases of streptococcal toxic shock syndrome (STSS) have been discovered in the country by June 2.

This is 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.

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

The rare flesh-eating bacteria—Group A Streptococcus or GAS—typically causes swelling and sore throat. However, in some cases, the bacteria can lead to rapidly developing symptoms, including limb pain and swelling, fever, and low blood pressure, which can be followed by necrosis, breathing problems, organ failure, and death. 

Kikuchi added that 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 also urged people to maintain hand hygiene and to treat any open wounds. People with an open wound are at increased risk for STSS, the US CDC said on its website. People with diabetes or alcohol use disorder, previously known as alcohol dependence or alcoholism, are at increased risk for STSS, it adds.