Mystery in Japan as dangerous streptococcal infections soar to record levels

Streptococcus pyogenes is behind most cases of streptococcal toxic shock syndrome, or STSS. Record numbers of cases are being reported in Japan, while the cause remains unclear. Photograph: Bsip Sa/Alamy

Experts warn that a rare but dangerous bacterial infection is spreading at a record rate in Japan, with officials struggling to identify the cause.

The number of cases in 2024 is expected to exceed last year’s record numbers, while concern is growing that the harshest and potentially deadly form of group A streptococcal disease – streptococcal toxic shock syndrome (STSS) – will continue to spread, after the presence of highly virulent and infectious strains were confirmed in Japan.