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The evaluation of patients with mould-related complaints is often difficult. Real illness and simply anxiety are often intermingled. This situation is made even more difficult by the absence of easily applied diagnostic tools. This FAQ list addresses some of the more common questions in this area.


What sorts of moulds are typical in the environment?

Aspergillus, Alternaria, Cladosporium, and Penicillium are the most commonly found moulds. Stachybotrys is usually present in only small amounts [96, 745].

Do I need to know what sort of mould is in the environment?

Not always. All of them should be treated with respect, as many can serve both as allergens and as sources of toxins. You might want to have detailed culture data if you were doing an outbreak investigation or other more detailed studies.

What sorts of diseases do moulds really cause?

Outside of the very different realm of true invasive mould infection, moulds produce two broad categories of diseases: Allergies and Toxicoses. The allergies are simply those of the classic forms of hay fever, asthma, rhinitis, and so forth. The toxicoses are much different. There are many, many different highly potent (A):toxins made by some fungi. Generally, these toxins produce disease after their ingestion. Thus, a good clue will be that of a history of ingestion of mould-contaminated foods. The toxicoses appear rare, although some authors have speculated that they may be more common than we think [1804].

How do I diagnose the allergic diseases?

The classic tools of the allergist apply here. These are well discussed in current textbooks.

How do I diagnose the toxicoses?

This one is much harder. There are no current tests that definitively diagnose any of the mycotoxin-related toxicoses. One can show that the fungus is in the environment and that it makes toxins (HPLC is usually required for this assay), but finding the toxins in people or animals is much more difficult. And, the issue of causality is always extremely difficult.

For example, Stachybotrys chartarum clearly makes toxins [1648, 2321]. It has clearly been associated with veterinary illness following ingestion of heavily contaminated foodstuffs [1046] and exposed farm workers have on occasion exhibited symptoms similar to those in the animals [1046]. However, linking the usual amounts of S. chartarum in the environment to disease in people has been difficult. For example, a (A):recent CDC investigation into a possible cluster of S. chartarum-related illnesses was confounded and confused by the typical problems of epidemiological investigation.

A key challenge in linking environmental moulds to the toxicoses is to figure out how the toxin gets into the patient. Short of ingestion of mould-contaminated foods or inhalation of large amounts of mould-containing dust, it can be difficult to understand the mode of spread. Aerosolization of spores by intermittent use of fans and airborne dispersal of volatile mycotoxins are two possibilities, but this area is poorly understood [745].

How do I approach the investigation?

First, the EPA publication entitled (E):Indoor Air Pollution: An Introduction for Health Professionals is a guide for physicians that specifically addresses the issues of evaluating building-related symptoms. It is highly recommended.

Having reviewed those data, the investigative approach should begin with a standard search for standard illnesses. If nothing is found and unexplained symptoms remain, you could consider the possibility of a mould-related illness. However, always keep in mind that mould are only one of many possible indoor pollutants that can cause symptoms. We provide a more detailed discussion of this on our sick building page, but things such as allergies to dust mites, photocopier fumes, carbon monoxide from stoves, and volatile organic compounds can all cause symptoms that are identical to those produced by mould infestation.

What advice should I offer the patient?

If you conclude that a mould might be causing the symptoms, the best advice is to point the patient in the direction of information that will assist him or her in removing visible mould from his or her environment. It is not possible to eliminate all traces of moulds–the goal is an environment that is clean, dry, free of visible moulds, and free of mould odors.

Other Resources

We provide specific literature references on most of our pages. However, we also have a separate page devoted just to a critical summary of the mould-related literature that is readily found on the web. Check it out!

About These Pages

The material and ideas here are drawn from many sources, including our own experience. However, this is an area with few guidelines and even fewer hard facts. So, you must always apply common sense in choosing how to adapt the ideas presented here to your own situation. When in doubt, please consult with a knowledgeable colleague. At times, there is simply no substitute for experience and personal knowledge.