Infectious disease detectives are puzzled by a mysterious spike in brain infections in Nevada children. One doctor said she's never seen anything like it.

• Last year the CDC investigated a cluster of brain abscesses among children that occured in Nevada.
• One area reported 18 brain abscesses in kids last year — more than four times the usual amount.

Health officials are puzzled by an increase in a rare type of children's brain infection that occured last year in Nevada, according to research presented at a Centers for Disease Control and Prevention conference April 27.

Researchers at the Southern Nevada Health District recorded 18 cases of brain abscesses, or pus-filled pockets of infection, in young Clark County residents in 2022 — mostly boys around 12 years of age.

Doctors working in the area said that the cases shared "striking" similarities, according to a CNN report. Fortunately, all 18 patients survived.

"In my 20 years' experience, I've never seen anything like it," Dr. Taryn Bragg, a pediatric neurosurgeon who treated all of the cases, told CNN.

Normally, Clark County health officials see about four brain abscesses a year, according to data from 2015-2021. During the COVID-19 pandemic, the number of abcesses was slightly higher, at around 7 a year. But Bragg told CNN there was a "huge increase" in brain abscesses in March 2022.

Many of the kids were sick with cold symptoms before they had abscesses

CDC investigators said that most of the children with brain abscesses had been sick with cold symptoms before they were diagnosed with a brain abcess. Some developed headaches and fevers, and a few were also diagnosed with ear and sinus infections.

But their symptoms either grew more serious or persisted. According to the CDC report, 11 kids sought medical care before hospitalization, and 15 of the 18 cases required a skull surgery to treat the abcess, also known as a craniotomy.

Brain abcesses are pockets of pus in your brain

Brain abscesses are pockets of pus in your brain, according to Johns Hopkins Medicine, usually caused by a bacterial or fungal infection. According to the Children's Hospital of Philadelphia, the abcess usually stems from a nearby site like an ear, sinus, or dental infection. An open head wound, or a heart or lung infection, may also give bacteria a chance to enter the brain.

In the Nevada cases, the most common cause of the brain abcesses seemed to be the Streptococcus intermedius bacteria, though it did not cause all of the cases.

Symptoms of a brain abscess may include headaches, fevers, and chills, as well as changes to a patient's vision, coordination, and balance. Loss of consciousness, partial weakness or paralysis, seizures, nausea, and vomiting may also occur, according to Johns Hopkins Medicine. If a child or adult has these symptoms, they should go to the hospital right away.

The CDC is still investigating the underlying cause of these cases

Investigators with the CDC said more research is needed to identify risk factors and causes of the increased number of brain abscesses. In the meantime, doctors in other parts of the country are also seeing an unusual number of pediatric cases, according to CNN.

An earlier look at the possible increase in pediatric brain abscesses, published in Morbidity and Mortality Weekly Report in September 2022, found a decline at the start of the pandemic followed by an increase in the summer of 2021 and a peak in March 2022. The authors said that pattern was consistent with seasonal fluctuations and the overall effects of the pandemic, but that they would continue to monitor the trend.

Bragg, however, noted that the CDC investigation ended as cases in Nevada were continuing to spike in 2022. She told CNN that the pace of cases appears to have declined lately, and just two kids have required treatment for brain abscesses in 2023.