Invasive group A strep infections are on the rise in the United States, particularly among children. Here's what you need to know about the spread, prevention, and treatment of these infections. 

Cases of iGAS are on the rise

Streptococcus pyogenes, or strep A, is a common bacterial infection that typically leads to mild symptoms, such as rash, fever, or swollen tonsils.

However, when strep A invades parts of the body where bacteria is not typically found, such as the blood, bone marrow, brain, or heart, it can spread quickly and lead to severe symptoms—even death.

Last month, CDC issued a health advisory warning about a "recent increase in pediatric invasive group A streptococcal (iGAS) infections." According to the agency, the rise has "occurred in the setting of increased circulation of respiratory syncytial virus (RSV), influenza viruses, SARS-CoV-2, and other respiratory viruses" in some instances.

The first reports of unusual invasive strep A activity came from the Netherlands between March and July. Since then, more cases of serious illness from invasive strep A have been reported in the United States, France, the United Kingdom, Ireland, and Sweden.

In the United States, cases of invasive strep A have been reported in Colorado, Minnesota, Missouri, and Texas. In November, there were 46 cases in Minnesota, more than double the average 20 cases in prior months. Similarly, Texas Children's Hospital reported more than 60 cases of invasive strep A in October and November, a fourfold increase from the same time last year.

In addition, the Colorado Department of Public Health and Environment (CDPHE) reported an increase in iGAS cases in November. While the increase was reported among individuals ranging from 10 months to 6 years old, CDPHE noted that any age group can become infected with strep A.

Still, the World Health Organization (WHO) noted that children under age 10 are the most impacted group. "Enhanced surveillance activities have been implemented in the countries reporting an increase in iGAS cases," WHO said last month. "An alert has been issued to other countries to be vigilant for a similar rise in cases and to report any unexpected increased national or regional incidence of iGAS infections to WHO."

What you need to know about iGAS

The streptococcal bacteria is spread through contact with an infected individual, including through coughing, kissing, sneezing, or touching. Outbreaks often occur in facilities with frequent close contact, such as schools or care homes.

Health experts have said that good hand washing hygiene, covering the nose and mouth when coughing or sneezing, and using alcohol-based hand sanitizer, can help prevent the spread.

Currently, there is no vaccine for strep A, but most infections can be treated with antibiotics.

"Keeping up to date on vaccines for COVID-19, flu, and chickenpox can help protect your child from developing complications from a group A strep infection," said Rachel Herlihy, state epidemiologist at CDPHE. "Stay home when you are sick and practice good hand hygiene … Call your child's doctor if they are experiencing new or worsening symptoms of an illness."

In CDC's advisory, the agency encouraged members of the public to learn about the symptoms of serious infections caused by strep A, including necrotizing fasciitis, streptococcal toxic shock syndrome, and cellulitis.

Many experts agree that the rise in strep A and iGAS are associated with the "tripledemic" of Covid-19, influenza, and RSV.

During the 2020 and 2021 winters, Covid-19 prevention measures led to low infection rates for many viruses. As a result, a large number of children were never exposed to standard childhood viruses during that time. Then, an early outbreak of RSV and influenza predisposed children to higher rates of group A strep.

While the rise in strep A and iGAS are associated with other respiratory illnesses, experts have noted there is no connection between the flu vaccine and strep throat. In fact, an influenza infection can lead to group strep A as a secondary bacterial infection. (Daignault, USA Today, 12/30; Suliman, Washington Post, 12/23)