What you should know about strep A, the usually mild infection killing kids in the U.K.

Health agencies are issuing warnings to parents about invasive group A streptococcus (iGAS), a common bacterium that usually causes mild illness but can sometimes result in severe cases and even death in young children.

Last week, the Centers for Disease Control and Prevention said it is “looking into a possible increase” in iGAS infections among children in the U.S., and on Monday the World Health Organization said a number of European countries have reported an increase in iGAS disease among children under 10 years old.

In France and the United Kingdom, the number of iGAS cases observed in children “has been several-fold higher than pre-pandemic levels for the equivalent period of time,” the WHO said.

Earlier this month, the UK Health Security Agency (UKHSA) said the U.K. is experiencing “an out of season increase” in strep A infections. Since September, 85 iGAS cases have been reported in children ages 1 to 4 years old throughout the U.K., and in England 13 children under the age of 18 have died.

What is strep A?

Strep A is responsible for a number of different infections, including scarlet fever and common illnesses like strep throat. It spreads easily through contact with an infected person or exposure to respiratory droplets after an infected person sneezes or coughs.

Dr. Wafaa El-Sadr, a professor of epidemiology and medicine at Columbia University, told Yahoo News that strep A infections are usually mild and often involve symptoms such as a sore throat or localized skin rash. But, very rarely, strep A can become more invasive, entering the bloodstream and causing severe illness or death.

“The mild skin infections and sore throats are not considered invasive because they're superficial to the surface of the mucosa in the throat or the surface of the skin,” El-Sadr said. “But once you get a deeper infection, then it can be quite serious. For example, dissemination into the bloodstream could also cause pneumonia sometimes in some people. So anything beyond the surface of the upper respiratory tract and surface of the skin is considered invasive, and that usually means that it's more severe.”

The CDC says infections stemming from iGAS include necrotizing fasciitis and streptococcal toxic shock syndrome — two rare, invasive bacterial infections that spread swiftly through the body and can result in death. Unlike a typical strep A infection, an iGAS infection is indicated by signs including high fever, confusion, difficulty breathing, nausea, vomiting and a rash that spreads to the entire body, with the illness quickly worsening soon after symptoms appear.

While anyone can be susceptible, iGAS is usually found in young children, adults over 65 years old and immunocompromised people. Still, UKHSA deputy director Colin Brown said in a statement that while an increase in cases may be “concerning for parents,” iGAS “remains very uncommon.”

Why is there a possible uptick in iGAS cases?

UKHSA said last week that it's investigating the increase in iGAS cases in children, but that “currently, there is no evidence that a new strain is circulating.”

“The increase is most likely related to high amounts of circulating bacteria,” the agency said. “It isn’t possible to say for certain what is causing higher than usual rates of these infections. There is likely a combination of factors, including increased social mixing compared to the previous years as well as increases in other respiratory viruses.”

Respiratory viruses such as RSV, influenza and COVID-19 have been wreaking havoc on health care systems since September. El-Sadr explained that while it’s hard to pinpoint a reason for a possible uptick in iGAS cases, the respiratory viruses currently circulating can weaken the body’s defenses — making it easier for bacteria like strep A to penetrate and cause severe illness like iGAS.

“The hypothesis is that when you get influenza, the virus can then compromise the various layers of the respiratory tract that are protective, and that makes the individual more susceptible,” she said. “Then, if they're exposed to [strep A], it can then move on to causing an iGAS infection.”

What should you do if you think your child has strep A?

If you or your child is experiencing strep A symptoms, you should visit your health care provider or an urgent care center to do a rapid test, which can determine if strep A is the culprit. If you receive a positive test result, your doctor will prescribe antibiotics, and you should begin to feel better within a day or two of starting treatment.

If you think you or your child may have iGAS, El-Sadr said you should seek medical attention immediately. But she reiterated that in general parents don’t need to panic.

“It's very rare,” she said of iGAS. “And I think that's why it's important to put this in perspective. The vast majority of people have the milder manifestations of [strep A] that are easily treatable with antibiotics.”

What can you do to protect your kid?

There is no vaccine for strep A, but the WHO notes that coinfection of viruses with strep A “may increase the risk of iGAS disease,” so it’s important to make sure your child gets the seasonal flu vaccine.

“People often think influenza vaccination is just to prevent severe influenza, but it also can prevent potential severe consequences of [other] infections,” El-Sadr said.

She said it’s also important to return to some of the measures used early in the COVID-19 pandemic that were effective at preventing illness, such as washing your hands, keeping your hands away from your face and mouth and staying home when you’re sick. Some health experts in the U.K. are also encouraging the use of face masks to reduce transmission of strep A by respiratory droplets.

“We can remind everybody the mantra from COVID: If you're sick, don't go to work, don't go to school, don't go to day care. Keep your child at home,” El-Sadr said. “If all parents do this, then that will prevent transmission to others.”