Where mould hides - Strefa Alergii
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Where mould hides

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Autumn. For some, it is a period of rest due to the end of the tree and grass pollen season, while for others it is the beginning of the annual malaise. What is responsible for the appearance of allergy symptoms during this period? It is the filamentous fungi, or moulds.

Where can we find mould?

Alternaria alternata and Cladosporium herbarum are quite abundant in the outdoor environment as well as in libraries, archives, and museums. Furthermore, the colonisation of fruit and vegetables by Alternaria, contributes to large economic losses among farmers. Often crops, especially potatoes, suffer from fungal infection. In addition, our homes and dwellings can be a source of exposure. Poor or insufficiently ventilated rooms, pets, carpets, and potted plants create ideal conditions for the growth of Aspergillus and Penicillium fungi in our homes. This situation can lead to the so-called Sick Building Syndrome, which becomes full of biologically active, harmful substances. Symptoms that appear among people living in such a building are:

  •  headaches
  • skin rashes
  • rhinitis
  • cough
  • memory disorders
  • asthma-like symptoms [1,2].

What allergy symptoms can moulds cause?

Allergic rhinitis can be observed in people with an allergy to filamentous fungi. This manifests itself as a feeling of nasal congestion, leakage of watery discharge, sneezing and itching. Mould spores are also a cause of bronchial asthma. 45% of children and up to 70% of adults with asthma have a known allergy to moulds [2]. Alternaria is responsible for severe asthmatic episodes and the occurrence of treatment-resistant asthma. In addition, ingestion of moulds by people with a known allergy may be associated with an acute reaction including anaphylactic shock [1]. Hypersensitivity to Aspergillus may also be implicated in the occurrence of AD. Why? Because one of the proteins found in this mould has a similar structure to a protein found in both one of the yeasts that make up the physiological bacterial flora of human skin and in the skin itself. As a consequence, this leads to inflammation of the skin [3].

Mould and possible cross-reactions

  • One of the cross-reacting proteins is enolase. It is widely distributed among filamentous fungi. For this reason, cross-reactivity is suggested between Alternaria alternata, Cladosporium harbarum, Aspergillus fumigatus, Saccharomyces cerevisiae, and Candida albicans [1]. This means that a person with an allergy to one type of filamentous fungi may exhibit allergy symptoms after contact with others. The literature of the subject describes a case of an 8-month-old boy with an allergic reaction after consuming one of the probiotic yeasts, Saccharomyces boulardii. Within 2 hours, he developed a severe allergic reaction requiring medical intervention. Upon another attempt to administer the yeast to the boy, the symptoms recurred. Therefore, based on the symptoms, Saccharomyces boulardii-induced fungal enteritis syndrome was diagnosed. Allergic reactions after consuming probiotic yeasts are rare but possible. Another fungus, Saccharomyces cerevisiae, is present in bakery products and, in turn, contributes to the occurrence of asthma symptoms among bakers [4].
  • The next cross-reactivity we may see among people with an allergy to filamentous fungal enolase is a reaction with latex. An allergic person may experience unpleasant symptoms after contact with latex, which will not be due to a direct allergy to this substance. They will be caused by the above-described cross-reactivity occurring between the proteins of the stroma and latex [1,3,5].
  • A rather surprising cross-reaction that can be observed in people with an allergy to Alternaria is an allergic reaction after eating spinach. This is due to the similarity of one of the proteins found in both spinach and Alternaria.
  • The literature of the subject also indicates that it is possible for people with an allergy to Alternaria to develop symptoms after eating mouldy cheese and ripened sausages [1].
  • As indicated in some studies, there is a possibility of an allergic reaction following the ingestion of raw and cooked mushrooms in people with a mould allergy [1,6].

Mycotoxins of filamentous fungi – is there anything to fear?

Mycotoxins are substances produced by filamentous fungi that are very harmful to the health of both healthy and allergic people. Mycotoxins are produced by Alternaria, Aspergillus, Penicillium and other filamentous fungi. Their negative effects on the body are quite widespread, as they show toxic effects on the kidneys, liver and nervous system and have carcinogenic and mutagenic effects on the developing foetus. Alternaria toxins can be found in vegetables such as potatoes, tomatoes, carrots, and peppers, and in fruit, for example dried figs, sultanas, olives, citrus fruits, strawberries, apples, pears, apricots, and melons. Prepared juices and jams are also another source of mycotoxin exposure [1].

Diagnosis of mould allergy

To confirm or exclude an allergy to filamentous fungi, skin spot tests, a lip test and molecular tests performed from blood are performed [1,6]. The ALEX platform offers the possibility to quantify the amount of antibodies present against mould and yeast molecules and extracts, which significantly facilitates the diagnosis of people experiencing symptoms after contact with moulds.

How do you minimise the risk of developing symptoms of an allergy to filamentous fungi?

  • Allergy sufferers should avoid rooms with traces of mould. Mould can hide on the walls of rooms, in exposed bathrooms and around windows, so attention should be paid to these problem areas in our homes.
  • Garden work should be avoided: weeding and planting plants and raking up grass and leaf debris, as this can trigger allergy symptoms.
  • Plants that decorate the windows of our houses and flats can unfortunately be a source of mould. It is necessary to periodically check the appearance of the soil in which they grow. It is often necessary to remove the flowers from the house altogether.
  • Aquariums also require our great attention due to the possibility of mould proliferation.
  • In addition, the Alternaria allergen can hide in heavily ripe watermelon, so this must be kept in mind when deciding to eat this fruit.
  • Food with visible mould should not be eaten. Cutting off a piece of mould does not remove it from the fruit or vegetable. Such a product is not fit for consumption and should definitely be discarded [1].


translation: Julia Majsiak

[1] K. Buczyłko, Nie tylko alergeny: Alternaria alternata. Alergia, 2016, 4: 17-22.
[2] Birgit Simon-Nobbe, Ursula Denk, Verena Pöll, Raphaela Rid ,,Michael Breitenbach, The Spectrum of Fungal Allergy, Int Arch Allergy Immunol 2008;145:58–86
[3] P. M. Matricardi, J. Kleine-Tebbe, H. J. Hoffmann, R. Valenta et all, EAACI Molecular Allergology User’s Guide, Pediatric Allergy and Immunology 2016:137-142, 281.
[4] Jin-Bok Hwang, Kyung JI Kang, Yu Na Kang, Ae Suk Kim, Probiotic Gastrointestinal Allergic Reaction Caused By Saccharomyces Boulardii, Annals Of Allergy, Asthma & Immunology, Volume 103, JULY, 2009, 87-88.
[5] S. Wagner, H. Breiteneder, B. Simon-Nobbe, M. Susani, M. Krebitz, B. Niggemann, R. Brehler, O. Scheiner, K. Hoffmann-Sommergruber, Hev b 9, an enolase and a new cross-reactive allergen from Hevea latex and molds, Purification, characterization, cloning and expression, Eur. J. Biochem. 267.
[6] P. A. L Dauby, B. A Whisman, L. Hagan, Cross-reactivity between raw mushroom and molds in a patient with oral allergy syndrome, Ann Allergy Asthma Immunol. 2002 Sep;89(3):319-21.