Strefa Alergii | ABC of allergies

Cladosporium. How do we know it’s sensitising us?

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Data publikacji: 2024-08-20
To be read in 5 minutes
Cladosporium herbarum is a fungus that produces microscopic spores that are often responsible for mould allergies. Although we sometimes see mould at first glance, we are mostly unaware of the presence of its allergenic spores in the air. How does an allergy to Cladosporium manifest itself? And what effects can it have?

Cladosporium herbarum and other types of microscopic fungi

Cladosporium is a large and diverse family of microscopic fungi that are widespread throughout the world and significantly affect the environment. They number about 800 species and are biologically adapted to spread freely over long distances [1]. They tend to grow on decaying vegetation and in soil.

jabłka w koszyku, na skórce jabłek pleśń cladosporium

They have a pathogenic effect on plants, meaning that they contribute to lesions such as leaf spot (they attack cereals, pumpkins, tomatoes). They are also not indifferent to human health. They live in our immediate surroundings, but they also penetrate the body and can therefore – under certain circumstances – lead, for example, to the development of allergies, asthma and lung fungus [1]. Fungi of the genera Alternaria and Cladosporium, followed by Penicillium and Aspergillus, are the most important sources of mould allergens [2]. Species that are most commonly responsible for inhalant allergy are:

  • Alternaria alternata,
  • Cladosporium herbarum,
  • Cladosporium cladosporioides,
  • Aspergillus niger [3].

Alternaria is very abundant in Mediterranean climates. In Poland, it predominates in the south of the country. Cladosporium, on the other hand, multiplies mainly in the Baltic and North Sea regions [4].

Scientific studies indicate that about 10 per cent of people worldwide develop antibodies to moulds and that the rate of sensitisation is steadily increasing [3]. New mould allergens are also constantly being discovered [2].

Microscopic spores, invisible allergens

pleśnie w domu, cladosporium

Fungi can sometimes be seen with the naked eye, e.g. in the form of variously coloured patches on walls and food. If the colour of the mould is brown, one may suspect a Cladosporium fungus [4]. However, allergen sources are not only mycelium, but also spores, which are the end product of the fungal reproduction process [2]. Such microscopic particles easily enter the respiratory tract, are invisible and thus difficult to detect [4]. One grain of grass pollen corresponds in volume to as many as 200 spores of Cladosporium herbarum species! [2].

Mould spores – unlike pollen – are present in the atmosphere practically all year round (in varying concentrations). However, mould allergy symptoms may only appear seasonally, especially in autumn and winter, when we spend most of the day in poorly ventilated closed rooms. Reservoirs of allergenic microscopic fungal particles are house dust and air-conditioning systems [2]. Cladosporium fungi can also form in refrigerators and on window frames [5]. People working in swimming pools, saunas and palm houses are particularly exposed to these fungi [4].

However, the period of maximum concentration of mould spores in the air is, contrary to appearances, not in autumn and winter, but in summer (June to August) [2]. In the second half of summer, mould spores may even be more important allergens in the outdoor environment than pollen. The temperature range favourable for fungal growth is 18-28 degrees C [5]. Their concentration outdoors increases with increasing average daily temperatures and rainfall [6]. With species of the genera Alternaria and Cladosporium being able to survive even in dry environments. Other factors, such as wind speed and atmospheric pressure, also influence fungal abundance [6].

Mould allergy – symptoms and diagnosis

The number of days on which the concentration of Cladosporium spores in air samples in Poland exceeds the trigger for allergic reactions in susceptible individuals (2800 per 1 m3 of air) ranges from 61 to 93 (depending on location) [7]. This means that the spores of these fungi can induce allergic symptoms in us for 2-3 months of the year. What the sites with the highest annual Cladosporium concentrations have in common is their location on agricultural plains [7]. Up to 10,000-15,000 spores per m3 of air float over agricultural fields [7,8].

The predominant symptom in people with an allergy to mould spores is nasal obstruction. At the highest concentrations of these allergens in the air, shortness of breath and paroxysmal cough also occur [8]. It is interesting to note that Cladosporium – in contrast to Alternaria allergens – gives virtually no conjunctival complaints [8].

If symptoms of an allergy to Cladosporium are present, it is advisable to visit an allergologist and begin diagnosis. To detect an allergy, point skin tests (PTS) are performed to identify hypersensitivity to multiple mould species. These tests can be performed either with single mould species or with a mixture of allergens of different species. A second option is blood tests for the determination of allergen-specific class E antibodies in serum. Less frequently, spirometrically monitored provocation tests are performed. In addition, the physician may order cytological and biochemical tests for the composition of nasal washings, bronchoalveolar lavage or sputum [9].

Cladosporium – cross allergy

In most people with mould allergy, hypersensitivity to several fungal species coexists, e.g. to both Cladosporium and Alternaria. Sensitisation to Cladosporium alone is rare [6]. In addition, mould allergens show cross-reactivity [2]. This means that with inhalant allergy to moulds, the ingestion of some cross-reacting proteins may cause food allergy symptoms. The main allergenic molecules Alternaria alternata (Alt a1) and Cladosporium herbarum (Cla h1), for example, are similar to proteins found in edible mushrooms, baker’s yeast and spinach. Bee products that are sometimes contaminated with Cladosporium fungi may also pose a risk. Hidden or cross-reactive allergens can even cause anaphylaxis [6]. Anaphylactic reactions in people with a mould allergy occur, for example, after eating yeast-based pasta sauces [10].

[1] Bensch K., Braun U., Groenewald J.Z., Crous P.W., The genus Cladosporium (2012). Studies in Mycology, 72, 1–401.

[2] Grzyby mikroskopowe. OBAS – Serwis Alergologiczny. Online: http://www.alergen.info.pl/Alergeny/Grzyby_mikroskopowe

[3] Durska G., Alergia na Cladosporium (2012). Medycyna Praktyczna. Online: https://www.mp.pl/pacjent/alergie/lista/71776,alergia-na-cladosporium

[4] Bogacka E., Alergia na grzyby pleśniowe: diagnostyka i leczenie (2008). Polski Merkuriusz Lekarski Medpress, XXIV, supl. 1, 11–14. Online: https://medpress.com.pl/pml/ePUBLI/T24S1/02.pdf

[5] Grinn-Gofroń A. i in., Zarodniki Cladosporium w powietrzu wybranych miast Polski w 2014 r. (2014). Alergoprofil, 10, 32–34.

[6] Xing H., Wang J., Sun Y., Wang H., Recent Advances in the Allergic Cross-Reactivity between Fungi and Foods (2022). Journal of Immunology Research, 1, 1–10. Online: https://onlinelibrary.wiley.com/doi/epdf/10.1155/2022/7583400

[7] Weryszko-Chmielewska E. i in., Health hazards related to conidia of Cladosporium – biological air pollutants in Poland, central Europe (2018). Journal of Environmental Sciences, 65, 271–281. Online: https://www.sciencedirect.com/science/article/abs/pii/S100107421630345X

[8] Rapiejko P. i in., Progowe stężenie pyłku roślin niezbędne do wywołania objawów alergicznych (2007). Otolaryngologia Polska, 61(4), 591–594. Online: https://www.sciencedirect.com/science/article/pii/S0030665707704912

[9] Wiszniewska M., Alergia dróg oddechowych na grzyby pleśniowe uwarunkowana ekspozycją komunalną i zawodową: występowanie, czynniki ryzyka, obraz kliniczny. Rozprawa na stopień doktora nauk medycznych (2007). Łódź.

[10] Popescu F.-D., Cross-reactivity between aeroallergens and food allergens. World Journal of Methodology, 5(2), 31–50. Online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4482820/

[11] Ogórek R. i in., Characteristics and taxonomy of Cladosporium fungi (2012). Mikologia Lekarska, 19 (2), 80–85. Online: https://www.researchgate.net/publication/233818972_Characteristics_and_taxonomy_of_Cladosporium_fungi

[12] Breitenbach M., Crameri R., Lehrer S.B. (eds.), Fungal Allergy and Pathogenicity (2002). Chemical Immunology and Allergy, 81, 48–72.