Toddler dies after rapid-onset encephalitis linked to flu, parents say

A 23-month-old girl from Wokingham died after developing encephalitis that clinicians said was triggered by influenza, her parents and doctors said. Lorelei Cowmeadow, who had been described by her family as a lively toddler, was taken ill with what appeared to be a routine winter cold and deteriorated within hours, becoming unresponsive and fitting before she was rushed to hospital.

Lorelei’s parents, Jack and Antonia, said the child had mild cold-like symptoms one Sunday in November and attended nursery the next day. By that evening she had been energetic and was dancing in front of television children’s programmes, but was woken during the night crying and asking for a bottle. Within moments she began to fit in her father’s arms, became difficult to rouse and exhibited abnormal movements and eye-rolls, the parents recounted. They called emergency services and she was taken by ambulance to the Royal Berkshire Hospital in Reading and later transferred to the John Radcliffe Hospital in Oxford for specialist care. She died on November 21, 2024, three days after first becoming critically ill and three days before her second birthday.

Doctors diagnosed Lorelei with encephalitis, a condition in which the brain becomes inflamed and can swell, causing tissue damage because the skull restricts expansion. Encephalitis can be caused by direct viral invasion of the central nervous system or by an overactive immune response that mistakenly attacks brain tissue. In Lorelei’s case, clinicians concluded that influenza had caused the inflammation.

Prof. Benedict Michael, chair of infection neuroscience at the University of Liverpool, said encephalitis affects about 6,000 people a year in the United Kingdom and carries a fatality rate of about 10 to 20 percent. He said the condition is more likely to affect very young children and older people with weakened immune systems. "Any virus has the potential to trigger encephalitis — but not everyone who is infected with these viruses will develop it," Dr. Ava Easton, a senior research fellow in encephalitis at Liverpool and chief executive of Encephalitis Research, said. "It’s not known why one person goes on to develop encephalitis when another doesn’t."

Clinicians said infectious encephalitis is most often caused by herpes simplex and varicella zoster viruses but can be triggered, less commonly, by influenza or measles. In some cases the body’s immune response may release high levels of inflammatory chemicals called cytokines that contribute to brain swelling. Symptoms can begin with nonspecific flu-like signs, including fever, headache, nausea and vomiting, and progress rapidly. More specific neurological features of infectious encephalitis may include sensitivity to light, neck stiffness, difficulty moving or speaking, weakness in limbs or face, seizures and drowsiness. Autoimmune encephalitis can present more slowly and may cause confusion, psychosis, seizures, hallucinations and memory loss.

Diagnosis usually relies on a combination of brain imaging, blood tests and analysis of cerebrospinal fluid obtained through lumbar puncture to detect inflammation. Early treatment is critical, doctors said, because there is often a limited window in which interventions can reduce the risk of death or long-term disability. "In most cases, there is a window of opportunity where early intervention improves survival," Prof. Michael said. For suspected viral causes, clinicians routinely start antiviral agents while investigations proceed. Acyclovir, which targets herpes simplex and varicella zoster, is known to improve outcomes when given promptly and is cited as providing an 80 to 90 percent chance of survival if administered within the first 24 hours for those infections. Ganciclovir may be used in immunocompromised patients with certain viral infections. Autoimmune causes are treated with medicines that suppress the immune response, such as corticosteroids, alongside supportive care for seizures and other complications.

Experts and family members emphasised that encephalitis is often missed because early symptoms can resemble common viral illnesses. Dr. Easton urged greater awareness among clinicians and the public, saying many people in the United Kingdom are unfamiliar with the condition. A 2021 YouGov survey cited by advocacy groups found that an estimated 77 percent of the public did not know what encephalitis was.

Lorelei’s parents said clinicians initially treated her with antivirals and steroids and placed her in an induced coma, but scans and tests showed extensive brain swelling and injury. The family later made the decision to donate her kidneys; hospital officials told them the organs were successfully transplanted into a 40-year-old woman. "We want some good to come out of this tragedy," Jack said. Antonia added that they hoped sharing their experience would prompt parents and clinicians to consider encephalitis when a child’s behaviour changes or they seem unusually unwell.

Medical professionals said anyone concerned about a sudden change in behaviour, worsening headache, seizures or new neurological symptoms should seek urgent medical assessment so encephalitis can be ruled out or treated quickly. Early recognition and rapid initiation of appropriate antiviral or immunosuppressive therapy can alter outcomes in many cases, clinicians said, but the condition remains unpredictable and can progress very quickly despite treatment.