Friday June 13 2008
Coloured scanning electron micrograph of the fungus Aspergillus fumigatus
“Gardener dies after inhaling killer fungus” is the headline in the Daily Mirror today, describing a case of a 47-year-old man who “went to hospital with chest pains just a day after opening a bag of rotting leaves”. The man died three days later from aspergillosis, which he contracted after inhaling spores from a fungus that grows on dead leaves (Aspergillus fumigatus).
Healthy hobbyist gardeners should not be panicked by this story. Aspergillosis infection is rare and is unlikely at the levels of exposure to compost experienced by most people. Gardeners who are likely to be exposed to large quantities of compost may consider wearing a mask. Health professionals should be aware of this case and investigate whether cases with similar symptoms and history are linked to aspergillosis.
Where did the story come from?
Dr Katherine Russell and colleagues from Wycombe Hospital in Buckinghamshire, UK reported this case, which was presented to their hospital. It was published in the peer-reviewed medical journal The Lancet.
What kind of scientific study was this?
The research behind the news stories was a case study – an observation of a single patient who had reported to the hospital. The clinicians described the man’s medical history, their investigations to identify the problem, their findings, the outcome of the case and their conclusions.
What were the results of the study?
A 47-year-old man – a welder by trade – was admitted with a history of cough, pleuritic chest pain (a sharp pain worsened by breathing, coughing and movement), increasing shortness of breath, fever and myalgia (muscle aches). He had previously been in good health, although he was a smoker. Other features at presentation included high fever, high breathing rate, irregular chest X-rays, high white blood cell count and crackling sounds in the lung while breathing. The initial assumption was that he had pneumonia, so he was put on antibiotics while further investigations took place.
After 24 hours, the patient was transferred to intensive care because of extreme shortness of breath. His condition worsened, and he showed signs of kidney distress and sepsis (high heart rate, low blood pressure and fever in response to infection throughout the body). The clinicians found that a fungus called Aspergillus fumigatus grew from the man’s saliva samples. Aspergillosis – the infection caused by the fungus – is common in immunocompromised people, such as those with HIV; however, this patient was HIV negative.
Clinicians established from his partner that the symptoms started less than 24 hours after he spread rotting tree and plant mulch from a sack around the garden. Clouds of dust had “engulfed him”. The clinicians consequently started him on another antibiotic – amphotericin B – for this infection. Less than 12 hours after admission to intensive care, he was transferred to a specialist unit where he could receive lung and heart support through a machine. Despite this, his blood pressure remained low, his kidneys began to fail and, although his blood was filtered to support his kidneys, his condition worsened to the degree that 72 hours after arrival at the specialist centre, he was withdrawn from the heart-lung machine and died shortly afterwards.
What interpretations did the researchers draw from these results?
The clinicians conclude that the patient experienced an acute invasive pulmonary aspergillosis infection. Although this infection would normally be seen only in immunocompromised patients, they say that “smoking and welding could have damaged his lungs and increased his susceptibility to infection”. The clinicians also say that “because he died so quickly”, they cannot rule out an undiagnosed immunodeficiency.
The clinicians add that although acute aspergillosis following contact with decayed plant matter is rare, it “may be considered an occupational hazard for gardeners”. They recommend that quick and appropriate treatment for the fungal infection is essential.
What does the NHS Knowledge Service make of this study?
There are two issues to keep in mind when taking on board the results of this study and the various newspaper articles about it:
- This is a case study of a relatively rare infection in response to exposure to a fungus. Gardeners should not be overly worried that their occupation or hobby has suddenly become a dangerous one. Gardeners are likely to be exposed to a variety of bacteria and mould, which are present in the soil and the compost that they use. In healthy individuals, these do not usually cause serious infections. As the clinicians acknowledge, they are not sure whether the patient described here may have actually had a compromised immune system; this would have made him more susceptible to the infection. It may be sensible for gardeners who are working with large amounts of compost or leaves to wear a mask. The average healthy hobbyist gardener is unlikely to have to take excessive precautions against exposure.
- Practising healthcare professionals will be interested in this case as it suggests that they should consider this infection in other cases that present with similar symptoms and similar histories.
Sir Muir Gray adds...
Aspergillosis infection is always a risk, but it won’t change my weekly composting work. However, if I worked with compost all the time I would probably wear a mask.