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'Unbelievable pain and suffering': How a common throat infection can rewire children's brains

Strep throat is jogo do bicho federal pernambucoa common childhood illness, but in a few children this bacteria infection can lead to alarming, lasting changes in behaviour. Scientists are now starting to unravel how it affects the brain.

On Charlie Drury's eighth birthday, his life changed forever.

It was November 2012 and the day had all the usual birthday fun – cake, presents and themed party food. But as the day wore on, Charlie's mother, Kate Drury, noticed something strange about her son's behaviour. It started with an eye twitch and then he kept sniffing his hands. Later in the day, he developed a fever. Drury took him to an urgent care clinic near the family's home in Illinois, US, where he was diagnosed with Streptococcal pharyngitis, also known as strep throat.

In the weeks that followed, Charlie's health deteriorated in ways that baffled Drury. He became so sensitive to smells that Drury had to stop cooking in the house. He developed extreme separation anxiety, yet his own mother's touch caused him to scream and scrub vigorously at the spot where their skin had met. He barely slept, became anorexic and refused to bathe. He hurled objects around their home. He hallucinated. He struggled to read and write. Drury barely recognised her son, who had previously been a promising student and athlete with no behavioural issues.

"I lost my child in a day," Drury says.

After more than a month of agony and confusion, physicians diagnosed Charlie with a little-known condition called "paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections", or Pandas.

Children with Pandas experience a stark and sudden onset of tics and/or signs of obsessive-compulsive disorder (OCD), with symptoms often appearing seemingly overnight. Just as suddenly, a child with Pandas may develop a litany of other issues including regressions in developmental or motor skills, aggressive and erratic behaviour, mood swings, pain, irritability and sleep disturbances, among others.

The condition's exact prevalence is hard to pin down, but experts agree Pandas is not common. One estimate says one in every 11,800 children might develop Pandas or a related condition called paediatric acute-onset neuropsychiatric syndrome (Pans) in a year, although the numbers do vary dramatically from study to study. They do, however, seem to be more prevalent among boys than girls, according to data from an international patient registry, and strikes children before puberty.

"For obvious reasons, parents are completely terrified" when these issues emerge, says Shannon Delaney, a child and adolescent neuropsychiatrist in private practice who treats patients with the condition in New York City, US. "I frequently hear them describe it as, 'It feels like my kid is not there. It feels like they're possessed'."

Researchers from the US National Institutes for Health (NIH) first described Pandas in the 1990s. Even at that time, the idea that streptococcal infections could cause neurological complications was not new. Doctors in 1894 had described patients with a neurological condition called Sydenham chorea after developing throat infections. Around 100 years later, a group led by Susan Swedo, then chief of the paediatrics and developmental neuroscience branch at NIH, published evidence that suggested strep infections were also linked to the startling and abrupt appearance of neuropsychiatric symptoms that are typical in Pandas patients.

How could strep throat – a routine illness contracted by hundreds of millions of children around the world each year – cause such an intense response among a small subset of kids?

This has been the subject of active scientific debate in the years that have followed. But Swedo, who is now chief science officer at the Pandas Physicians Network in the US, sums it up like this: "The wrong strep, in an unlucky child… leads to a misdirected immune response."

In other words, some children's immune systems – perhaps those with a genetic susceptibility – seem to misfire when trying to fight off a strep infection, producing antibodies that attack the body's own healthy tissues. These antibodies seem to get inside the brain and wreak havoc. Studies in animals suggest this may occur in some cases because immune cells produced in response to strep travel along nerves that run from the nose to the brain and weaken the brain's protective barrier.

Some scientists continue to question this hypothesis. But multiple research teams have published studies pointing to inflammation and other changes in the brains of children with Pandas – specifically in the basal ganglia, which plays a role in motor control, learning, decision-making and emotional responses. OCD has also been linked to dysfunction in the basal ganglia.

Jennifer Frankovich, a paediatric rheumatologist who directs the Stanford Immune-Behavioral Health Program in the US and whose team has produced some of the research on Pandas-related brain inflammation, says such findings are important because they indicate "this is a real disorder" caused by an autoimmune response, rather than a psychological condition.

For parents struggling with a child whose behaviour has suddenly and dramatically changed, that revelation alone can be valuable, particularly as there can be a tendency to blame it on poor parenting, says Frankovich.

Other common respiratory illnesses, including influenza, have been linked to Pandas-like symptoms, too. Preliminary research also suggests Sars-CoV-2, the virus that causes Covid-19, can either worsen existing symptoms or cause new ones – perhaps by increasing inflammation throughout the body and/or reactivating other dormant viruses in the body, one 2023 study theorised. Delaney's research and clinical experience suggests that tick-borne infections that cause Lyme disease may be a catalyst for symptoms, too.

When a pathogen other than strep seems to trigger sudden-onset neuropsychiatric symptoms – or when doctors can't identify a specific trigger – children are given the more general diagnosis of Pans. Although there are other differences in their diagnostic criteria, Pandas is considered a subtype of Pans.

Infections can prove disastrous for Pans/Pandas patients for years on end, says Sarah O'Dor, a clinical psychologist who directs the Pediatric Neuropsychiatry and Immunology Program at Massachusetts General Hospital in Boston, US. Pans/Pandas symptoms wax and wane, with children experiencing periods of near or total remission that can last years. But then, "if the child gets sick again with something – it might be strep, it might be Covid – suddenly these symptoms come back," O'Dor says.

Finding treatments for those symptoms, either when they first emerge or when they flare, can be an odyssey for patients and their families. Few clinicians specialise in Pans/Pandas, and some refuse to treat it or argue it doesn't exist at all. A study of children in the International Pans Registry found that 87% struggled to access appropriate care, for reasons including lack of experienced healthcare providers and difficulty securing insurance coverage.

When a child is taken for treatment, clinicians may see psychiatric symptoms and automatically prescribe psychiatric drugs. These medications can help in some cases, but they can also hurt – research suggests many Pans/Pandas patients are prone to side-effects even at relatively low doses. Others simply don't respond to them. Most patients need a "multi-pronged approach" that also addresses the infection that caused their initial or flaring symptoms and the immune effects thought to stem from that infection, O'Dor says.

If treatment starts early, routine medications like antibiotics, steroids, and even over-the-counter painkillers can make a world of difference, says Frankovich, who helped draft clinical guidelines for treating Pans/Pandas.

But when Pans/Pandas goes untreated for a long time or is particularly severe, patients may need more intensive and invasive therapies, like intravenous immunoglobulin (infusions of donated antibodies, often abbreviated to IVIG) or plasma exchange therapy (a procedure that removes and replaces tainted plasma in a patient's blood), according to these clinical guidelines.

In 1999, Swedo published research suggesting that IVIG and plasma exchange therapy are effective against Pandas symptoms. Nearly 30 years later, "it's ridiculous that children are not getting help", she says.

But the science on Pans/Pandas treatment isn't entirely settled. A small?2016 study that Swedo co-authored did not find a statistically significant difference between IVIG treatment and a placebo. Two years later, a European research review concluded that more rigorous research on treatment is needed.

Nonetheless, many patients swear by the results provided by treatments like IVIG. When Drury's son developed Pandas more than a decade ago, she was willing to pay thousands of dollars for his first IVIG treatment – which, she says, "brought him back to us". The experience prompted her to become an advocate, pushing for a state law that requires insurers to cover treatments including IVIG for Pans/Pandas patients.

"Charlie's Law" passed in Illinois in 2017 – but to this day, Drury says, it can be a struggle to get the right treatments for her son, who is now 20. Charlie has had long periods of remission, but also multiple severe flare ups. Clinicians have told him he will need regular IVIG infusions, as well as plasma exchange therapy, for the rest of his life, says Drury.

"We'd be in these hospitals and they're like, 'We can't help you'," Drury says. "Even though there's a law in his name."

Pans and Pandas are today recognised by global health authorities – the World Health Organization has added Pandas to its disease classification system, for example – and researchers and patient support groups across the world are working to improve quality of care and access to it. In the UK, Pans and Pandas were the subject of a 2023 parliamentary hearing.

But skepticism still remains in some areas. In a 2025 report, the American Academy of Pediatrics described Pans as "likely" to be a valid diagnosis, but added that "the diagnostic process is challenged by a lack of well-accepted evidence to guide the clinician" and that "much remains unknown about the condition".

It's true that there is no single test that can diagnose Pans or Pandas, nor a biomarker that definitively signals their presence. Brain changes associated with these conditions are also so subtle that they don't show up to the naked eye on imaging tests, Frankovich says. "When the radiologist reads the MRI, they're looking with their eyeballs and they're like, 'Oh, this is a normal brain'," Frankovich says. "So these poor patients are getting dismissed."

Researchers continue to study Pans/Pandas, hoping to learn more about why they happen, what goes on in the bodies of patients who have these conditions, and whether there are biomarkers that could enable easier diagnosis and open the door to new treatments. One is Brent Harris, a neuropathologist at Georgetown University in Washington DC, US, who oversees the Pandas/Pans and Other Neuroimmune Disorders Brain Bank.

The brain bank fills an important research gap. Studying the brains of Pans/Pandas patients who have died allows for more granular analysis than doctors could perform when they were alive, he says. Through this work, Harris and his colleagues have found additional evidence of inflammation in the basal ganglia and other parts of the brain. Harris hopes such discoveries could eventually provide new targets for treatment.

Still, Harris stresses that far more research is required. His laboratory, for example, is working with only nine donated brains, and a much larger number would be needed to make generalisations about these diseases.

One of those donors is Alissa Johnson, who lives in New Jersey, US. Her daughter, Louisa "Lulu" Johnson, died in 2021 after "two and a half years of unbelievable pain and suffering" brought on by Pandas, made worse by "lack of awareness" and "difficulty accessing care", Johnson says.

Lulu's Pandas symptoms began just after New Year's Day in 2019, when she was 11. "We came home [from a trip] on the first," Johnson remembers. "On the second, it was like she woke up in a totally different body."

Johnson's previously "happy, healthy, and thriving child" suddenly had no appetite and severe gastrointestinal distress, struggled to sleep and acted in strange, frightening ways – including trying to climb out of a moving car.

Lulu was hospitalised multiple times over the winter and spring that followed, testing positive for strep in February 2019. Still, it took months for the family to receive a Pandas diagnosis, a lull during which Lulu was given drugs that didn't help, including psychiatric medications that triggered bad reactions.

Even once a Pandas diagnosis came, Johnson says, getting proper treatment was not easy. "Our paediatrician's office wanted nothing to do with us following the diagnosis," Johnson says. And one emergency room visit, during which Johnson refused to admit her daughter to a psychiatric institution, resulted in a call to Child Protective Services, she says.

Eventually, Lulu was treated with immune-system-altering drugs, including IVIG, that led to steady improvement. But after a string of medication changes, her condition deteriorated until her death in 2021.

"Her dream was to become an immunologist and help patients like her," Johnson says. Since her passing, Lulu's parents have tried to honour that dream in other ways. They founded the Louisa Adelynn Johnson Fund for Complex Disease to raise awareness for and fund research on neuroimmune conditions. And they have posthumously donated Lulu's blood and brain tissue to Georgetown's brain bank, while allowing her test results to be used in other studies.

It is a cold kind of comfort, Johnson says. "It's really sad," she says, "to have people acknowledge how sick she was only after she's dead."

But as scientists slowly unravel the mystery of Pandas, they inch closer to realising Lulu's dream: sparing other children from lives upended by what should otherwise be a simple throat infection.

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