CDC Finds Significant Increase in Invasive Strep Throat Strain in Several States

A study found that rates more than doubled over a nearly decade-long period. The incidence was high among those 65 and older, among others.

The Centers for Disease Control and Prevention headquarters in Atlanta on April 23, 2020. (Tami Chappell/AFP via Getty Images

The frequency of invasive group A strep infections more than doubled over a nearly 10-year period, according to a study published by the U.S. Centers for Disease Control and Prevention this week.

The study, led by CDC researchers and published in the JAMA Network on April 7, looked into invasive group A streptococcus bacterial infections (GAS) collected through a network known as the Active Bacterial Core, which covers 10 states and around 35 million people.

Invasive GAS infections can cause a wide range of symptoms, including strep throat, but they can develop into life-threatening conditions such as necrotizing fasciitis, a flesh-eating disease that can rapidly spread.

The study noted that cases of the bacterial infection in the United States stood at 3.6 per 100,000 people in 2013. But the rate increased to 8.2 per 100,000 by 2022, they found. They looked at more than 21,000 total cases of the infection over the nine-year period.

“Incidence was particularly high among those 65 years or older, American Indian or Alaska Native persons, residents of long-term care facilities, people experiencing homelessness, and people who inject drugs,” the authors wrote, adding that “accelerated efforts to prevent and control GAS are needed.”

“In any of its forms, from skin and soft tissue infections, pneumonia, bone and joint infections, or sepsis without a clear clinical focus, invasive GAS can be insidious and unpredictable, testing the lifesaving capacity of even the world’s most advanced medical facilities,” Joshua Osowicki, researcher with the Royal Children’s Hospital Melbourne, wrote in an accompanying editorial published in JAMA.

“Surges of invasive and noninvasive GAS disease in 2022 and 2023 have been reported in countries spanning the Northern and Southern Hemispheres, with new reports of the same phenomenon still coming to light.”

In an article published on the CDC’s website last year, preliminary data collected in 2023 showed “the number of serious infections caused by group A strep reached a 20-year high” and that the “number of serious group A strep infections has been increasing in the United States over the past decade.” Cases have also occurred “primarily in adults,” it added.

Health officials, including the Mayo Clinic, say that “mild” strep infections include cellulitis, an infection that impacts tissues underneath the skin; impetigo, sores and blisters around the mouth, nose, or arms and legs; sore throat; strep throat; and erysipelas, an infection that impacts the upper layers of the skin.

But severe forms of the condition can include bloodstream infections; scarlet fever, which causes a rash, sore throat, and high fever; toxic shock syndrome, an infection that impacts several organs; rheumatic fever, which causes inflamed joint and heart tissues; and necrotizing fasciitis, the flesh-eating disease.

Severe symptoms include diarrhea, dizziness, fever, nausea or vomiting, skin color changes from red to purple, swelling skin that can be warm to the touch, or large wounds, blisters, or black spots on the skin, according to the clinic.

Outside the United States, Japanese health officials warned in March 2024 about a jump in potentially deadly strep throat infections, with cases running about three times higher than a year earlier in Tokyo.

Reuters contributed to this report.