By LUKE ANDREWS U.S. SENIOR HEALTH REPORTER
Ahead of flu season, parents are being warned that healthy children could develop a life-threatening condition after being infected with the virus.
More than 6million children are infected with flu every year. Most recover without medical care, but among patients under five years old, between 6,000 and 25,000 are hospitalized annually while about 37 to 199 died from the disease.
But in 2023 doctors anecdotally reported an uptick in acute necrotizing encephalopathy, or a dangerous brain swelling that kills about one in four patients.
The condition happens when the immune system overreacts to a viral infection and damages the blood-brain barrier, causing damage to brain tissue and brain swelling.
A review published this week in JAMA found there were 41 cases in children across the last two flu seasons, making it ‘extremely rare.’
But three-quarters of those affected were considered healthy, and most were around five years old.
Of the children, all were hospitalized and 11, or 27 percent, died from the disease, with death occurring within three days of symptoms starting.
Only 16 percent of patients had received the flu vaccine, which the CDC recommends children aged six months and older get once a year.
Doctors are sounding the alarm over acute necrotizing encephalopathy that can, in rare cases, strike healthy children who develop the flu (stock image)
Dr Nicholas Dragolea, a primary care physician in the UK who was not involved in the research, told DailyMail.com: ‘I see a lot of adults and children with flu every winter.
‘Acute necrotizing encephalopathy is one of those extremely rare but extremely serious complications that happens predominantly in children.’
The warning comes ahead of then next flu season, which typically begins in October. Up to 40million Americans are infected with the disease every year.
Acute necrotizing encephalopathy is caused by an overreaction from the immune system to a viral infection, most commonly the flu.
This triggers high levels of inflammation in the body that disrupts the blood-brain barrier and causes damage and swelling in brain tissue.
Patients initially suffer from congestion, a cough, diarrhea or fever, but within days they develop fainting, seizures, trouble breathing and difficulty with movement.
Treatment involves anti-viral medications to kill the virus and steroids or anti-inflammatory drugs to calm the immune system.
In the study published in JAMA, researchers contacted 76 academic organizations across the US to ask members to submit reports of cases of acute necrotizing encephalopathy.
Millions of children catch flu every year and most recover without needing medical care (stock image)
They received reports of 41 cases detected between October 2023 and May 2025 from 23 hospitals nationwide.
The patients had an average age of five years old, and three out of four were considered to be healthy and had no previous health conditions. Twenty-three of the patients were female.
In the group, 38 developed a sudden onset of fever, while 41 patients had encephalopathy, or swelling in the brain, and 28 suffered from seizures.
Eleven of the patients died, or 27 percent.
Among those who were hospitalized, they were on wards for between 11 and 22 days before being discharged.
Of the 38 patients with vaccination history, six were vaccinated against the disease, equivalent to 16 percent.
Children are more at risk from the disease because their immune systems are still developing and may overreact to a virus, causing the complication.
Older people and those with weaker immune systems are also more at risk, as their weaker immune systems raise the risk of an infection that could then cause an overreaction.
It isn’t clear why there may have been an uptick in cases, but doctors say this could be linked to lockdowns which led to children receiving fewer exposures to ‘good microbes’ which can cause their immune systems to overreact to other infections.
It comes after the CDC raised the alarm over the condition in March, saying a dozen children had contracted the rare brain disorder.
In a report, it said of the 68 children who died of the flu during the 2024 to 2025 season, nine had encephalopathy and four had acute necrotizing encephalopathy.
This article was originally published by a www.dailymail.co.uk . Read the Original article here. .