I am sure you were all horrified to read of the death of a small child in England and to see the press photographs of the mould in his house to which his death was attributed by the coroner. Such awful conditions are not uncommon in both privately and publicly owned flats and in houses rented to the poor and disadvantaged; they are a consequence of damp and poor ventilation.
You may even have seen the beginnings of such infestations in your kitchen or bathroom and will probably know that washing them away with household bleach solves the problem. But I suspect strongly, from past experience, that many people on finding black mould in their flats will be feeling panicky about possible fatal consequences and may be seeking medical advice. Pictures send a strong message, in this case even sending the Secretary of State to visit the bereaved parents.
All of you will have noticed the black colour of the fungus on the walls and some will have made the connection with the black spots on fallen leaves at this time of year. This shows that at least one, and probably the main fungus, was Aspergillus niger
. But before I say more, I should point out that death from inhaling fungal spores is exceedingly rare – indeed, I have never seen or seen reported such a case before. So please don't panic and I'll explain what I think was going on, though I only know what I have read in the press about this distressing individual case.
I first thought about fungal diseases when asked in a postgraduate exam to write an essay on their effects on the lung. At the time, I had no knowledge of the subject and had to bluff my way through with guesswork and some basic biology. But when I became a chest specialist, I started seeing some patients who had developed allergies to Aspergillus
and other patients who had the fungus growing in parts of their lungs that had been damaged by previous tuberculosis. Obviously, the organism was getting into their lungs through spores in the air.
At that time, I also had a small research group interested in airborne allergens, pollens and fungi, and we knew how many different fungi there are in the air that we (and you) inhale every time we take a breath. But only one of those fungi was associated commonly with allergies and lung infestation – Aspergillus
– and only then in predisposed people such as those with asthma, cystic fibrosis, or on immunosuppressant drugs. I discovered that it also affected wild birds and cattle. Why Aspergillus
and not Penicillium
or any number of others in the air? We eventually found an answer.
Most fungi are soil organisms, living on organic matter including other living organisms. For some years, I hosted some on and off between my toes, inaptly in my case called athlete's foot. In the soil, these organisms compete for survival and have mechanisms of attack and defence. Aspergillus
has developed a mechanism of paralysing its attacker, perhaps an amoeba, and then feeding on it. Higher animals are only accidental hosts. Our lungs have also developed defences against inhaled germs – these defences include cells which act like amoebae to swallow and kill the germs.
Fortunately, we also have other defences and when we inhale potentially dangerous fungal spores we eliminate them easily, unless our other defences are impaired as in cystic fibrosis, immunosuppression, and sometimes asthma. In these cases, the balance may be shifted and the Aspergillus
may set up residence in the lungs, causing worsening asthma symptoms or sometimes an allergic inflammation in the deep lung which is easily treated. Only in the seriously immunosuppressed does the fungus become truly infective and cause a form of blood poisoning.
That last sentence seems not to be true of the case of the poor child. Although he was said to have asthma, there is no suggestion that he was immunosuppressed. However, it is pretty clear that he had prolonged and very heavy exposure to spores, and in these extreme circumstances it is likely that his lung defences would have been overwhelmed and the Aspergillus
was then able to invade his blood stream.
There are many young and not so young people now in Britain living in damp flats. A pair of young friends are in one such. It is impossible to ventilate such accommodation well in the Scottish winter and all washing and drying may need to be carried out in the space available. My friends found black mould and eliminated it with bleach and bought a dehumidifier, which extracts seven litres of water each day from their flat.
Changing the relatively low-cost housing stock is a long-term problem. Dreadful episodes such as this recent death are fortunately exceedingly rare but cold and damp accommodation has long been known to be associated with recurrent winter infections and allergies, and must constitute an important burden on health services. Following the recent widespread publicity, I hope landlords and housing authorities will start to take damp seriously. It is yet another of the many disadvantages faced by the poorest in our divided society.
Anthony Seaton is Emeritus Professor of Environmental and Occupational Medicine at Aberdeen University and Senior Consultant to the Edinburgh Institute of Occupational Medicine. The views expressed are his own