The recent alert issued by public health officials in Tokyo about the escalating number of invasive group A Streptococcus infections, including cases of streptococcal toxic shock syndrome (STSS), has brought to light some critical concerns regarding the epidemiology of this severe infection. Having encountered numerous cases of STSS in my practice as an infectious disease, emergency medicine, and critical care physician, I have witnessed firsthand the devastating impact of this condition. Despite initial presentations that may appear to be benign streptococcal bacteremia, the reality of STSS quickly unfolds with a ferocity that can be likened to a destructive tornado tearing through the body.
In the span of just over three months in 2024, Japan has reported a staggering 500 cases of STSS, a number that has already surpassed half of the previous year’s record high. These cases in Japan seem to be associated with skin and soft tissue infections, although any site of group A streptococcal infection can potentially trigger the aberrant immune response characteristic of STSS. The predominant strain responsible for these infections in Japan is identified as M1UK, a highly toxic and transmissible variant that has been proliferating globally. Measures are being taken in Japan to not only warn the public but also to cancel large events in an effort to prevent the spread of infection.
The underlying factors contributing to the changing epidemiology of STSS and invasive group A Streptococcus infections remain unclear. Speculations include increased diagnosis rates following the COVID-19 pandemic, which may have created a larger pool of susceptible individuals due to reduced social interactions. The phenomenon observed in Japan underscores the importance of understanding the carriage rates of the M1UK strain, as carriers serve as potential reservoirs for infection. If carriage rates are on the rise, it could signify a shift in the dynamics of Streptococcus epidemiology, prompting the need for decolonization strategies among high-risk carriers.
The surge of group A streptococcal infections post-pandemic in Japan mirrors similar trends observed in other countries, including the United States. Enhanced surveillance for invasive group A streptococcal infections and STSS, along with strain characterization, is crucial in the post-pandemic era. Clinicians worldwide must remain vigilant and familiarize themselves with the complexities of STSS, including optimal treatment approaches such as the use of intravenous immunoglobulin (IVIG) to mitigate the severe outcomes associated with this infection. It is imperative for healthcare providers to recognize STSS as a distinct entity that requires prompt and intensive intervention, rather than conflating it with other forms of sepsis. The alarm raised by the events in Japan serves as a stark reminder for clinicians globally about the looming threat posed by this formidable infection.