Are Deadly Strep Infections on the Rise? Here's What to Know

Japan has been experiencing a dramatic rise in cases of streptococcal toxic shock syndrome (STSS), according to the country's National Institute of Infectious Diseases (NIID) and as reported in the Japan Times.

In 2023, a record 941 cases of STSS were reported in Japan, outpacing the record 894 cases that occurred in 2019. So far this year, 517 cases have been documented in the country, with cases occurring in 45 of 47 of the country's prefectures.

This week, the Tokyo Metropolitan Government issued a warning to residents about the disease, as 88 cases have already occurred in the city since the beginning of the year -- more than half of last year's total number. Specific factors that are fueling the surge remain unknown. The mortality rate for STSS in Japan is 30%, according to the NIID.

Japan's health authorities are now urging people to take basic preventive measures to ward off infection with group A Streptococcus (GAS), the bacteria that causes STSS, such as hand-washing and appropriate wound care. Aside from STSS, GAS causes other invasive infections such as cellulitis, necrotizing fasciitis, and pneumonia.

Invasive GAS Infections in the U.S.

"We've had issues in the U.S. with this organism ... so we've been aware of this for some time now," George Diaz, MD, an infectious diseases specialist and division chief of medicine at Providence Regional Medical Center in Everett, Washington, told MedPage Today.

Diaz pointed to recent CDC data that showed a decrease in invasive GAS infections during the COVID-19 pandemic, most likely due to preventive measures, such as isolation and quarantining. "We believe there's a resurgence in cases after those sorts of measures have been relaxed," he said.

Overall, invasive GAS infections have been increasing in the U.S. over the past decade, primarily in adults, and preliminary data from 2023 indicated that the number of invasive GAS infections reached a 20-year high. However, during the COVID pandemic, cases decreased by up to 25% compared with the years right before the pandemic, and infection numbers were especially low in children. In late 2022, that trend reversed, with invasive GAS infections increasing to levels higher than those seen in pre-pandemic years, particularly for children. In December 2022, the CDC issued a health advisory about recent increases in pediatric invasive GAS infections in multiple states.

CDC data from the last 5 years showed that approximately 14,000 to 25,000 cases of invasive GAS disease occurred each year in the U.S. and 1,500 to 2,300 people died annually from these infections. In contrast, several million cases of milder GAS-associated illnesses, such as strep throat, scarlet fever, and impetigo, occur annually in the U.S.

Diaz noted that the apparent spike in cases of STSS in Japan may be in part due to heightened vigilance in diagnosing the condition there. "It could be that what Japan is seeing is that they're being very careful about identifying these cases. And so they're seeing these high numbers, especially in mortality, versus in the U.S. where we may not be quite as good as Japan in identifying and tracking these cases," he explained. It is not uncommon for milder forms of STSS to be underdiagnosed, he added.

STSS can result from invasive or noninvasive GAS infection, but typically occurs when bacteria enter through compromised skin or mucus membranes, with the main sites of entry being the vagina, pharynx, mucosa, and skin or soft tissue, and then spreads systemically and in the bloodstream. However, the route of entry remains unknown for up to 50% of cases.

Early symptoms of STSS include influenza-like symptoms, such as fever, myalgia, nausea, and vomiting. As the disease progresses, it is associated with soft tissue necrosis, as well as multi-organ involvement, including renal impairment, coagulopathies, liver involvement, and acute respiratory distress syndrome. Mortality rates from STSS range from 30% to 70%, even with aggressive antibiotic treatment and hospitalization.

STSS is more common in people ages 65 and older, those who have recently had surgery, and in people with diabetes or alcohol use disorder. GAS can be transmitted via droplets and contact with contaminated surfaces, but transmission can be reduced by standard infection control practices, including good hand hygiene and respiratory etiquette.

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