Disease detectives from the US Centers for Disease Control and Prevention (CDC) are investigating a cluster of rare and serious brain abscesses in children in and around Las Vegas, Nevada.
Doctors in other parts of the country are also reporting a possible increase in cases.
In 2022, the number of brain abscesses in children in Nevada tripled, increasing from an average of four to five cases annually to 18.
“In my 20 years’ experience, I’ve never seen anything like it,” said Dr. Taryn Bragg, an associate professor at the University of Utah who treated the cases.
Pediatric neurosurgeons like Bragg are rare. She is the only one for the entire state of Nevada, and because she treated all the cases, she was the first to notice the pattern and to alert local public health officials.
“After March of 2022, there was just a huge increase in brain abscesses,” Bragg said. “I was seeing large numbers of cases, and that’s unusual.”
“And the similarities in terms of the presentation of cases were striking,” Bragg said.
In almost every case, children would develop a common childhood ailment, such as an earache or a sinus infection, along with a headache and fever. Within about a week, it would become clear that something more serious was occurring.
After a presentation on the Nevada cases at the Epidemic Intelligence Service Conference on Thursday, doctors from other regions said they are also seeing similar increases in brain abscesses in children.
“We’re just impressed by the number of these that we’re seeing right now,” said Dr. Sunil Sood, a pediatric infectious disease specialist at Northwell Health in New York.
He estimates they are seeing at least twice as many cases as usual, though they haven’t conducted a formal count. He urged the CDC to continue investigating and work to spread the word.
Brain abscesses are not reportable conditions, meaning doctors aren’t required to notify public health departments when they encounter these cases. They typically only come to the attention of public health officials when doctors notice increases and reach out.
Brain abscesses are pus-filled pockets of infection that spread to the brain. They can cause seizures, visual disturbances, or changes in vision, speech, coordination, or balance.
The earliest symptoms are headaches and a fever that comes and goes. Abscesses often require several surgeries to treat, and children may spend weeks or even months in the hospital recovering.
In the Clark County cluster, roughly three-quarters of the cases were in boys, and most were around age 12.
Dr. Jessica Penney, the CDC Epidemic Intelligence Service officer assigned to the Southern Nevada Health District, the health department that investigated the cases, presented her investigation of the Clark County cluster at the CDC’s annual Epidemic Intelligence Service conference on Thursday.
Penney says they looked at various factors to determine the cause of the increase, including travel history, prior Covid-19 infection, underlying health conditions, and common activities or exposures. They found no common links.
Penney and her team then decided to review historical brain abscess cases in children under 18 going back to 2015.
From 2015 to 2020, the number of brain abscess cases in Clark County remained stable at around four per year. In 2020, the number of cases dipped, likely due to social distancing, school closures, and masking measures
implemented during the pandemic, which reduced the spread of all respiratory infections, not just Covid-19. In 2021, as restrictions eased, the number of cases returned to normal levels, but in 2022, there was a significant spike.
“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 had these exposures without that immunity from the years prior, we saw a higher number of infections.”
This idea is part of a theory called immunity debt. Some doctors believe that during the pandemic, because children weren’t exposed to the usual number of viruses and bacteria, their immune systems became less capable of fighting off infections.
This may explain the recent increases in several serious childhood infections, including invasive group A strep.
However, Sood is skeptical of the immunity debt theory. He thinks Covid-19 temporarily displaced other infections, essentially crowding them out.
Now, as Covid-19 cases have declined, other childhood infections are resurging. He points to the unprecedented surge in RSV cases last fall and winter as an example.
Sood says brain abscesses usually follow a very small percentage of sinus infections and inner ear infections in children. With the increase in these infections, the number of brain abscesses has also risen proportionally.
If immunity debt or a higher burden of infections were to blame, it would make sense for brain abscesses to increase in other regions as well.
Last year, the CDC worked with the Children’s Hospital Association to monitor and count brain abscesses in children nationwide to determine if there was a national spike.
Data collected through May 2022 did not detect any 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 noticed a significant rise in cases in her area starting in spring 2022.
She says the CDC continues 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 Streptococcus intermedius, a type of bacteria that normally exists harmlessly in the nose and mouth.
However, when it enters the bloodstream or brain, it can cause problems, such as after dental work or in individuals with weakened immune systems.
In the Clark County cluster, the affected children were healthy with no prior significant medical history that would make them more susceptible. There wasn’t any known immunosuppression or similar conditions, Bragg says.
Sood adds that most of the children they are seeing with brain abscesses are older, in grade school and middle school.
At this age, children’s sinus cavities are still developing, making them particularly vulnerable to infection. These small spaces can fill with pus and burst.
When this occurs over the eyebrow or behind the ear, where the barrier between the brain and sinuses is thinner, the infection can spread to the brain.
Parents may not always recognize the signs of a sinus infection in children. If a child develops a cold or stuffy nose and then wakes up with a red and swollen eye, or an eye swollen shut, it’s essential 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.
Bragg reports that in 2023, she has treated two more children with brain abscesses, but the pace of new cases seems to be slowing down, which she hopes continues.
Some children needed multiple brain and head and neck surgeries to clear their infections.
Sood mentions that in his hospital, there is a patient who has been hospitalized for two to three months and undergone five surgeries, although this is an extreme case.
Penney says the CDC will continue to monitor the situation closely.
“We’re going to continue to monitor throughout the year, working very closely with our community partners to see what happens in Southern Nevada,” she said.
