Fungi are microscopic, single-celled organisms which - contrary to bacteria - have cell nuclei. Fungi do not contain chlorophyll and therefore cannot photosynthesise. Instead, they get all their nutrition from their growth medium.
It is estimated that there are about 100,000 fungus species - possibly even more. Fungi contribute to the breakdown of organic material. They are found everywhere in nature; in the soil, in the air, in the water, and in people. One gram of soil can contain up to 100,000 living fungal spores.
Some fungi exist in colonies and can therefore be seen with the naked eye. Examples of fungal colonies are mildew on bread or mould on bathroom tiles. Other fungal colonies resemble plants. These are found in nature as mushrooms and puffballs. Some of them are edible, others are very poisonous.
Fungi can be divided into 4 categories: Phycomycetes, ascomycetes, basidiomycetes, and imperfect fungi. They propagate in several ways, both sexually and asexually, by simple transverse partition, by means of a kind of germination, and by several kinds of spore formation. Fungi require stabile humidity in order to thrive. They also require nutrition and proper temperature.
We use fungi for all sorts of everyday things. Yeast fungi are used to make bread, beer, and wine. Mould fungi are used to make moulded cheese, penicillin, and various enzymes for industrial use. In the wastewater industry, fungi help clean the water of various impurities.
An estimated 300 fungal species are involved in diseases in humans and animals. Disease-provoking fungi can be subdivided into three groups: mould fungi, yeast fungi, and dimorphic fungi.
Mould fungi
These are filiform growths that form a coherent network, called a mycelium, which grows down into a growth medium but can also be seen on its surface. This causes these fungal colonies to have the woollen or hairy appearance we know as mildew. Mould fungi thrive in poorly constructed, insufficiently maintained, and poorly ventilated residences. They live on wood, wallpaper, glue, plaster, paint, cork, and other organic materials in all of the places where moisture often accumulates. These fungi produce enzymes which break down their growth medium. The also produce many fungal toxins (mycotoxins) which are given off to the surround air, even when they dry out. These mycotoxins are smaller than fungal spores and dangerous if inhaled. They can stress the liver, kidneys, nervous system, and immune system. Typical symptoms in people who live in buildings with these fungi are therefore chronic tiredness, asthma-like symptoms, and irritation in the nose and eyes. Some mould fungi, however, require quite a lot of moisture to thrive. They all require oxygen in order to grow, and quite often you can smell their presence.
Yeast fungi
These can do without oxygen. They are characterized by being round and separated. However, they can also form filiform offshoots resembling those of mould fungi. See Candida albicans further down on this page.
Dimorphic fungi
These are a group of fungi that can take the form of both yeast- and mould fungi according to the temperature. In the body, which normally has a temperature of 37 degrees C (98.6 degrees Fahrenheit), they appear yeast form-like. Dimorphic fungi are usually not seen in Europe, but in North- and South America they cause lung- and skin infections.
Mycosis
Under certain conditions, microscopic fungi can cause disease in humans. Fungal diseases are collectively called mycosis. In residences attacked by mould fungi, liberated fungal particles and -spores are mixed with the air and inhaled. Fungi or fungal spores that are inhaled can cause cancer, meningitis, kidney disease, skin diseases, allergy, blood sugar problems, and mental sufferings. In less dangerous but still bothersome cases they can cause skin fungus, epidermophytosis, and onychomycosis, dandruff, chronic sinusitis, and thrush in babies. They are also called superficial mycosis. Severe fungal infections in which the internal organs are attacked are called deep mycosis. These are normally only observed in people with a severely reduced immune defence.
Mycotoxins
Harmful fungi excrete a group of metabolic products which are collectively called mycotoxins. They are produced by the fungus itself and usually not by its spores. Mycotoxins can be very different in structure and properties. The more moisture and warmth, the stronger the toxicity. However, we can benefit from certain mycotoxins; penicillin is an example of this. Alcohol is also a mycotoxin. Other examples of mycotoxins:
Mycotoxin - Most common damages - Can be found in / originate from
- Aflatoxin - The liver - Maize, nuts, and dried fruits from warm climates.
- Ochratoxin - The kidneys - Insufficiently dried cereals, pulses, coffee beans, wine.
- Ergot alkaloid - The vascular system - Cereals; rye in particular.
- Patulin - The gastro-intestinal tract - Fruits and products made from fruits.
- Fumonisin - The body's enzymes - Maize.
One fungus can produce several different toxins and thereby cause different symptoms and diseases. Mycotoxins are produced in large amounts in cereal that is too wet and have not been properly dried after harvest. They can be found in all kinds of tainted foods including rotten fruit. Mycotoxins can be found in meat- and dairy products from animals that have been given feed infected with fungi, and mycotoxins can be found on nuts. Mildew and mould on provisions are a clear indication of the precense of mycotoxins. Moulded cheese, however, is not toxic.
When foodstuffs are being heated, the fungi are destroyed but their toxins are not. Mycotoxins can damage nervous tissue and skin but especially they can destroy kidney tissue and cause liver cancer. The problem is particularly big in Africa.
Symptoms
Common symptoms of fungal attacks can be tiredness, headache; including migraine, runny and itching eyes, itching nose and skin, reddening, difficulties breathing; including asthmatic symptoms, concentration difficulties and memory problems.
Aspergillus
These are a family of mould fungi. Mostly known are A. flavus, A. fumigatus, A. niger, and A. terreus. The mycotoxin aflatoxin from some aspergillus fungi is one of the strongest toxins in the world. It is not produced, however, until the temperature reaches 25 degrees C (77 degrees Fahrenheit). An aspergillus infection in the airways can be the cause of allergy. If left untreated, an aspergillus infection can be deadly to persons with a reduced immune system.
Normally, the yeast fungus Candida albicans is present on skin and mucous membranes without causing any problems. In the human intestinal canal, however, it can in some cases spread inexpediently and form filiform offshoots that grow into and perforate the intestinal wall making substances flow into the bloodstream which should normally have been kept out. This strains the immune system and can cause a cascade of symptoms. This suffering is described separately as "Candidiasis".
Mouth Fungus
Is often caused by the above-mentioned Candida-fungus. In infants it is referred to as thrush. Fungus mouth can arise as an accompanying symptom after treatment with antibiotics, weakened immune system, after chemotherapy, badly regulated diabetes, accumulation of heavy metals in the body (for example after many years of smoking), dry mucous membranes (for example Sjogren's syndrome) and poor oral hygiene (Absence of tooth brushing or cleaning of mouth prosthesis).
Skin fungus
Skin fungus on the skin can be difficult to distinguish from eczema. A rule of thumb states that if the affected area of skin is sharply defined it is a fungal infection. If the borderline between the affected skin and the normal skin, however, is more diffuse it is a case of eczema. The fungi that attack skin, hair, and nails are collectively called dermatophytes but they belong to the mould fungi family. Skin fungus can also be caused by the yeast fungus Candida which thrive in folds of the skin in which there is a warm and moist environment. Skin fungi subsist on dead skin cells. The symptoms are reddening, stinging, and itching - sometimes with little blisters and small cracks.
Epidermophytosis
This is a common form of skin fungus and is typically caused by too much heat and moisture in your shoes. It is often a case of a fungus of the Trichophyton family but it can also be the candida fungus. The symptoms are itching and excoriation between the toes and there can be cracks in the skin. The fungus can spread to the sole of the foot and to the nails. Epidermophytosis can spread from person to person - especially where there are small cracks in the skin.
Ringworm (Tinea corporis)
This is a misleading designation for a fungal infection attacking the skin. The disease presents itself as round, well defined, red, desquamating dots. The infection often comes from pets - very often from cats.
Pityriasis versicolor
The yeast fungus Pityriasis versicolor presents itself on the body as small dots which can resemble a lack of skin pigment (vitiligo). The infection can develop in people using solariums.
