As respiratory viruses surge around the country, some states are also seeing an unusual rise in a rare and potentially deadly bacterial infection among children, Ariana Eunjung Cha writes for the Washington Post.

When a common bacterial infection turns dangerous

Streptococcus pyogenes, or strep A, is a common bacterial infection that typically leads to mild symptoms, such as rash, fever, or swollen tonsils. In the United States, several million people are infected by strep A every year, and with antibiotic treatments, it is "mostly a nuisance," Cha writes.

However, cases of a rare and potentially lethal form of strep A, or invasive strep A, among children have been rising in several European countries and the United States. 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.

The symptoms of invasive strep A are also not uniform, making it difficult for physicians to diagnose. Some symptoms that have been reported include skin rashes, fever, a racing heartrate, and unexplained swelling.

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 has reported more than 60 cases of invasive strep A in October and November, a fourfold increase from the same time last year.

"We were very surprised," said Angela Myers, director of infectious diseases at Children's Mercy Kansas City Hospital, which saw seven children arrive with invasive strep A infections in the last month. "We just don't see this many together in such a short time."

Around the world, over 25 children have died from the infection, including two deaths in young children in Denver, Colorado, which were reported last week.

Although invasive strep A remains relatively rare, providers are urging parents to lookout for potential warning signs as cases continue to rise.

"If a child looks sicker than they should be after they develop a fever, it's always a good idea to bring them to a doctor if they have trouble breathing, or you notice something else—even a swollen eye," Myers said.

"We don't want to raise too many alarms, but these infections can progress very rapidly," said James Versalovic, pathologist in chief at Texas Children's Hospital.

What's causing these 'superinfections'?

So far, it is not clear exactly what is driving the rise in these "superinfections" among children, Cha writes. One supposition is that the surge of respiratory viruses, including Covid-19, flu, and respiratory syncytial virus (RSV), may be impacting people's immune systems, making it easier for a secondary bacterial infection to occur and make its symptoms more severe in some cases.

According to Versalovic, many of the children with invasive strep A in the hospital have also had current or recent viral infections. However, he noted that there could also be other factors contributing to the severity of the children's strep A infections.

"It could be we have altered patterns of immunity due to the pandemic that may have increased our vulnerability. But it could also be … different variants" of strep, Versalovic said. "It could be a combination of factors. No one knows."

Myers agreed, saying, "I think there are a lot of things at play we don't fully know yet."

Currently, both the World Health Organization and CDC are investigating the invasive strep A cases, including whether the "viral storm" that has been plaguing many people may be partially responsible for the rise in cases.

According to CDC spokesperson Kate Grusich, it is still too early to tell whether cases of invasive strep A "are just returning to pre-pandemic levels, or if they are rising beyond what we would normally expect."

"CDC is watching these data closely, and talking with surveillance sites and hospitals in multiple states to learn more about any trends," Grusich said. (Cha, Washington Post, 12/21)