Woman Dies a Month After Falling Ill With the Flu and Developing Rare Immune System Condition: 'She Couldn't Be Saved'

A 25-year-old woman died weeks after developing flu-like symptoms that preceded a rare and potentially life-threatening immune disorder, with her mother saying doctors eventually told the family that 'she couldn't be saved.' Daisy Catterall, from Cirencester, Gloucestershire, died on 22 February 2025 after developing haemophagocytic lymphohistiocytosis, known as HLH.

Her mother, Rachel Catterall, said her daughter had been fit and active before becoming ill in January that year, when she first reported swollen glands in her neck. Doctors initially treated Daisy's illness as a viral infection, but she later developed aching joints and rashes as her condition continued to worsen.

Rapid Health Decline

Daisy returned for medical care several times before abnormal blood results led to her admission to hospital. She initially remained well enough that her parents, Rachel and Sam, travelled to Cambodia and Vietnam after Daisy was discharged for outpatient treatment.

Two days into the parents' trip, however, they were told that Daisy had been readmitted, and a consultant said doctors wanted to perform a bone marrow biopsy, according to a report by Gloucestershire Live.

Her parents immediately began travelling home, but Daisy's condition rapidly deteriorated. By the time Rachel and Sam returned to Britain, their daughter had been transferred to critical care, and doctors had diagnosed HLH.

Daisy's kidneys subsequently failed, requiring dialysis, and doctors placed her in an induced coma before she suffered a cardiac arrest and died hours later.

Rachel said that she watched medical staff try to save her daughter before being told there was nothing more they could do. She described seeing how severely the illness had affected Daisy's body and said the speed of her decline was difficult to comprehend.

Shortly before her medical emergency, Daisy had bought a home with her long-term boyfriend, Matty Ballinger, and had been making plans for their future together.

What Is HLH?

HLH is a life-threatening disorder in which a person's immune system becomes excessively activated and begins damaging the body's own tissues and organs. University College London Hospitals says secondary HLH can be triggered by infections, cancers, immune disorders and some medical treatments.

On the other hand, some cases have no clearly identified trigger. Symptoms can include fever, rash, fatigue, swollen lymph nodes and enlargement of the liver or spleen.

The condition can be difficult to recognise because its early symptoms overlap with other serious illnesses, particularly sepsis. Gloucestershire Hospitals NHS Foundation Trust advises clinicians to consider HLH in patients with persistent fever, falling blood-cell counts and raised ferritin levels.

Early specialist assessment and treatment are important because patients can deteriorate quickly and develop multiple-organ failure, as per the NHS Foundation Trust.

Family Raises Money for HLH Research

Since Daisy's death, her family and friends have raised more than $114,000 (£85,000) for HLH research at University College London Hospitals, according to local reporting. The fundraising has included endurance events and other challenges organised in her memory.

Researchers have said that the support helped make further research funding possible. Rachel has also spoken publicly about her late daughter's illness in an effort to increase awareness of the rare condition.