Doctors watching for more cases after mysterious cluster of brain infections strikes kids in southern Nevada by Brenda Goodman

Dr. Jessica Penney is the CDC Epidemic Intelligence Service officer, or “disease detective,” assigned to Southern Nevada Health District, the health department that investigated the cases. She presented her investigation of the Clark County cluster at the CDC’s annual Epidemic Intelligence Service conference on Thursday.

Penney says as they tried to figure out what was driving the increase, they looked at a slew of factors – travel, a history of Covid-19 infection, underlying health, any common activities or exposures – and they didn’t find anything that linked the cases.

Then, she says they decided to look back in time, looking for brain abscess cases in children under 18 all the way back to 2015.

“I felt like that helped us get a better sense of what might be contributing to it,” Penney said in an interview with CNN.

From 2015 to 2020, Penney says the number of cases of brain abscesses in Clark County was pretty stable at around four a year. In 2020, the number of brain abscesses in kids dipped, probably because of measures like social distancing, school closures, and masking – things that shut down the spread of all kinds of respiratory infections, not just Covid-19. In 2021, as restrictions began to lift, the number of these events returned back to normal levels, and then in 2022, a big spike.

A link to the pandemic?

“So the thoughts are, you know, maybe in that period where kids didn’t have these exposures, you’re not building the immunity that you would typically get previously, you know with these viral infections,” Penney said. “And so maybe on the other end when we you had these exposures without that immunity from the years prior, we saw a higher number of infections.”

This is a theory called the immunity debt. Doctors have recently seen unusual increases in a number of serious childhood infections, such as invasive group A strep. Some think that during the years of the pandemic, because children weren’t exposed to the number of viruses and bacteria they might normally encounter, it left their immune systems less able to fight off infections.

Sood said he’s not sold on the theory that there’s some kind of immunity debt at work. Instead, he thinks Covid-19 temporarily displaced other infections for a while, essentially crowding others out. Now, as Covid-19 cases have fallen, he thinks other childhood infections are roaring back – he points to unprecedented surge in RSV cases last fall and winter as an example.

Sood says brain abscesses normally follow a very small percentage of sinus infections and inner ear infections in kids. Because they are seeing more of those infections now, the number of brain abscesses has increased proportionally, too.

If immunity debt or a higher burden of infections were to blame, it stands to reason that brain abscesses might have increased in other places, too.

Last year, the CDC worked with the Children’s Hospital Association to find and count brain abscesses in kids, to see if there was any sort of national spike. Data collected through May 2022 did not detect any kind of widespread increase, according to a study published in the Morbidity and Mortality Weekly Report last fall.

But Bragg thinks the data cutoff for the study may have been too early. She says spring 2022 was when she saw cases in her area really take off. She says the CDC is continuing to collect information on brain abscesses and evaluate local and national trends.

About a third of the brain abscesses in the Clark County cluster were caused by a type of bacteria called Streptococcus intermedius that normally hangs out harmlessly in the nose and mouth, where our immune system keeps it in check. But when it gets into places it shouldn’t be, like the blood or brain, it can cause problems.

That can happen after dental work, for example, or when someone has an underlying health condition that weakens their immunity, like diabetes.

That wasn’t the case with the kids in the Clark County cluster, however.

“These are healthy children. With no prior significant medical history that would make them more prone…there wasn’t any known immunosuppression or anything like that,” Bragg says.

Like the cases in Clark County, Sood says most of the kids they are seeing are older, in grade school and middle school. He says until kids reach this age, their sinus cavities are underdeveloped, and haven’t yet grown to their full size. This may make them particularly vulnerable to infection. He thinks these small spaces may become filled with pus and burst. When that happens over the eyebrow, or behind the ear, where the barrier between the brain and sinuses is thinner, the infection can travel to the brain.

Sood says the signs of a sinus infection in kids can be subtle and parents don’t always know what to watch for. If a child gets a cold or stuffy nose and then the next day wakes up with a red and swollen eye, or an eye that’s swollen shut, it’s a good idea to seek medical attention. They may also complain of a headache and point to the spot above their eyebrow as the location of the pain.

On the lookout for new cases

Bragg says so far, in 2023, she’s treated two more kids with brain abscesses, but the pace of new cases seems to be slowing down – at least she hopes that’s the case.

Some of the children she treated needed multiple brain and head and neck surgeries to clear their infections.

Sood says in his hospital, doctors have a patient who has been there for two to three months and had five surgeries, although he says she was an extreme case.

Penney says the CDC continues to watch the situation closely.

“We’re going to continue to monitor throughout the year working very closely with our community partners to see you know what, what happens down in Southern Nevada,” she said.