Japan Sees New Record Number of Deadly Streptococcal Toxic Shock Infections

In 2017, Japan’s National Institute of Infectious Diseases reported its highest number of cases of toxic shock syndrome from Group A Streptococcus bacteria since record-keeping began. Now, Japanese health officials are trying to figure out why these deadly infections have been on the rise.

Group A strep causes a wide range of infections, from mild cases of strep throat, to scarlet fever, to life-threatening infections that can lead to organ failure. In rare cases, the bacteria can cause necrotizing fasciitis, a serious and sometimes deadly skin infection that quickly spreads and kills soft tissue. Invasive or noninvasive group A strep can lead to an illness called streptococcal toxic shock syndrome (STSS), typically caused by the Streptococcus pyogenes bacterium; it is known that these bacteria are capable of entering the body through wounds, however, sometimes, the cause of infection can remain unclear. Early symptoms of STSS can arise abruptly and include fever, chills, swelling, vomiting, diarrhea, muscle aches, and rash. The infection can quickly progress, leading to soft tissue necrosis, acute respiratory distress, shock, and multiple organ failure. The Centers for Disease Control and Prevention (CDC) notes that 30% to 70% of STSS cases are fatal, but when caught quickly the illness can be treated with intravenous antibiotics or via surgery to remove dead tissue.

According to recent news reports, Japan saw more cases of STSS in 2017 than it has since the country began keeping a record of these infections in 1999; Japan reported its first case of STSS in 1992. A surveillance report of notifiable diseases for week 50 of 2017 from Japan’s National Institute of Infectious Diseases (NIID) noted that 10 new cases of severe invasive streptococcal infections reported that week brought the year’s total to 539 cases. Tokyo and Kanagawa prefectures each reported 2 new cases that week, bringing the case count to 68 in Tokyo and 42 in Kanagawa—the 2 highest case counts of the 47 prefectures. Other prefectures reporting a high number of STSS cases include Aichi with 35 cases and Fukuoka with 31 cases.

In 2013, the country reported a total of 203 cases, and the annual case count has since continued to steadily rise. According to the NIID, in 2015, the number of cases reached 204 within the first 24 weeks of the year. The reason for the country’s recent rise in STSS cases remains a mystery to health officials. STSS infections in Japan tend to most commonly occur during the months from January to June. “It is conceivable that a growing number of patients with STSS are infected with bacteria other than group A streptococcus,” said Ken Kikuchi, a professor of infectious diseases at Tokyo Women’s Medical University, in a recent news report.

Japan’s National Epidemiological Surveillance of Infectious Diseases collects serotype isolates to better understand the growing number of streptococcal infections and monitor the isolates’ susceptibility to antibiotics. Because the disease can progress and become fatal within 24 hours even in individuals who are healthy, patients with STSS must receive antibiotics such as penicillin or clindamycin as soon as possible.