After a late-2022 surge in invasive strep A infections left at least two children in the U.S. dead, the Centers for Disease Control and Prevention say it has pinpointed the likely cause of the surprising wave of illness.
In a report published March 9, the agency wrote that last fall's increase in respiratory viruses — in particular respiratory syncytial virus, aka RSV — as well as kids' reduced exposure to Group A strep during the pandemic "might have predisposed children to (invasive strep A) infection when pandemic restrictions were lifted."
“Whenever we see a huge amount of respiratory viruses, we know we are going to see a bump up in bacterial infections,” Dr. Michael Green, medical director of infection prevention and antimicrobial stewardship at the UPMC Children’s Hospital of Pittsburgh, tells TODAY.com.
Group A streptococcus is a type of bacteria that can cause a range of illness, from strep throat and scarlet fever to skin infections. An invasive case of strep A refers to when the bacteria spread to parts of the body that they don't normally reach, like the bloodstream. This can cause severe and even fatal illness and requires immediate treatment with antibiotics, according to a warning the CDC issued about the increase in infections last December.
The CDC said it was first notified about a rise in infections in the U.S. in November 2022, when a hospital in Colorado saw a possible increase strep A cases, followed by a potential increase "in other states," per the warning. It did not specify which states.
"While the overall number of cases has remained relatively low and (invasive Group A strep) infections remain rare in children, CDC is investigating these reports," the agency said in the warning.
The new report from March provides more specific data. It noted that from Oct. 1, 2022, to Dec. 31, 2022, specific surveillance sites in Colorado and Minnesota saw 34 cases of invasive strep A. For comparison, in 2016, 2017, 2018 and 2019, there were 11 cases over the same three-month period. In 2020 and 2021, there were four.
The Colorado patients were also younger on average than in previous years — 3.1 years old versus 5.6. From 2016 to 2021, five children died from invasive strep at the surveillance sites in Colorado in Minnesota, compared to two deaths in 2022 alone.
Of the 34 patients, 21 of them, or 62%, had a recent respiratory infection before developing invasive strep A, and six recently had a sore throat. Fifteen of the 34 had tested positive for a respiratory virus leading up to or at the same time as their strep A infection. The report added that data from 2016 to 2022 show that increases invasive Group A strep infections tend to coincide with increases in RSV and flu hospitalization rates.
Last December, NBC News reported that hospitals in Arizona, Colorado, Texas and Washington confirmed they'd seen more cases than usual of invasive Group A strep. In Texas, one hospital saw an increase of four times in the number cases of invasive strep A.
The CDC estimates there are several million cases of noninvasive strep A in the U.S. every year — which includes strep throat, scarlet fever and the bacterial skin infection impetigo. Over the past five years, there have been between 14,000 and 25,000 cases of invasive strep per year and 1,500 to 2,300 deaths per year.
What is invasive strep A?
Strep A refers to the diseases that come from being infected with the bacteria called Group A streptococcus. Noninvasive illnesses from strep A, according to the CDC, include:
- Strep throat, which causes sore throat, pain with swallowing and fever. It's “a mild and common condition that can be easily treated,” according to the Colorado Department of Public Health and Environment.
- Scarlet fever, which commonly causes rash and fever.
- Impetigo, a highly contagious bacterial skin infection that starts as raised bumps on the skin followed by blisters containing pus followed by crusty lesions.
An invasive strep A infection — what the CDC has been investigating — refers to when the bacteria spread outside the throat or skin (where they tend to cause only mild symptoms) and into the bloodstream, lungs, fluid in the spinal cord or "other places inside the body they would not typically live," per the Colorado health department.
Conditions that result from an invasive strep A infection include:
- Cellulitis (a bacterial infection in the tissue under the skin) with a blood infection.
- Pneumonia, an infection in the lungs.
- Necrotizing fasciitis, popularly known as flesh-eating disease.
- Streptococcal toxic shock syndrome (STSS), "which can develop very quickly into low blood pressure, multiple organ failure, and even death," per the CDC.
Strep A is spread through contact with droplets from an infected person when they cough, sneeze or talk. Cases of Group A strep tend to follow a seasonal pattern, peaking between December and April in the U.S. It's most common in kids 5 to 15 years old.
Signs of severe strep A infections
Because a viral infection can make a bacterial infection more likely, parents of kids who recently had a viral illness should be vigilant about possible Group A strep infections, Dr. Ishminder Kaur, a specialist in pediatric infectious diseases at the UCLA, David Geffen School of Medicine, tells TODAY.com.
Signs of a Group A strep infection, per the Colorado health department, include:
- Sore throat
- New rashes
- Skin bumps
- Painful red patches on the skin
High fever and labored breathing, as well as "difficulty coordinating swallowing with breathing" in young kids, "should trigger parents to call their provider or to seek emergency care, depending on the seriousness of the situation," Kaur says.
Dr. Ethan Wiener, chief of emergency medicine at NYU Langone Health Hassenfeld Children’s Hospital, tells TODAY.com that a high fever by itself doesn't signal Group A strep and is "in no way harmful or dangerous." Parents should remember that if a child is very sick, it could be the flu, he says.
Signs a child's strep A infection may be invasive include:
- A change in mental status. "Maybe you’re not able to arouse the child, or the child may not be responding normally,” Wiener says. “That’s different from the child feeling blah or lying on the couch all day.”
- Early signs of necrotizing fasciitis, which, per the CDC, include: a red, warm or swollen area of skin that spreads quickly; severe pain, including pain beyond the area of the skin that is red, warm, or swollen; fever. Later-stage signs are: ulcers, blisters, or black spots on the skin; changes in the color of the skin; pus or oozing from the infected area; dizziness; fatigue; diarrhea or nausea.
- Early signs of streptococcal toxic shock syndrome, which, per the CDC, include: fever and chills, muscle aches, nausea and vomiting. Later signs, which usually develop 24 to 48 hours after the first symptoms, include: low blood pressure; faster than normal heart rate; rapid breathing; signs of organ failure, such as inability to produce urine or yellowing eyes.
While both necrotizing fasciitis and streptococcal toxic shock syndrome are rare, their symptoms can get worse quickly. So, in light of the strep A investigation, the CDC is urging parents to know the symptoms of both diseases and seek medical care quickly if they think their child has either.
Parents should also contact a health care provider right away if their child develops new or worsening symptoms during a viral infection, the Colorado health department advised.
How to prevent strep A infections
The latest CDC report suggests that getting the chickenpox vaccine and flu shot can reduce risk of invasive strep A because it can be a complication of both viruses. Group A strep infections had been going down since 1995, when the chickenpox vaccine became available, Wiener says.
Some children might need to flu shots this year, and it's not too late in the season to get them, TODAY.com previously reported.
In addition to getting vaccinated, to prevent strep A infections, the CDC recommends washing your hands often for at least 20 seconds or using an alcohol-based hand sanitizer, especially after coughing or sneezing and before preparing food or eating. You should also cover your coughs and sneezes with a tissue and dispose of it right away. If you don't have a tissue, use your upper sleeve or elbow and not your hands.
When in doubt about your child's condition, seek medical care. Even if it turns out it wasn't necessary, “it’s better than having a bad outcome,” Wiener says.