Common Mould Species

Aspergillus spp

Aspergillus is the most common genus of fungi in our environment with more than 160 different species of mould. Sixteen of these species have been documented as causing human disease. Aspergillosis is now the 2nd most common fungal infection requiring hospitalization in the United States .

Aspergillus fumigatus. The most encountered species causing infection. It is seen abundantly in decomposing organic material, such as self-heating compost piles, since it readily grows at temperatures up to 55 C. People who handle contaminated material often develop hypersensitivity to the spores of Aspergillus and may suffer severe allergic reactions upon exposure.

Aspergillus flavus. The 2nd most encountered fungi in cases of Aspergillus infection. It is also known to produce the mycotoxin aflatoxin, one of the most potent carcinogens known to man. In the 1960s, 100,000 turkey poults in Great Britain died from ingesting contaminated feed. Most countries have established levels for aflatoxin in food. However, the risks associated with airborne exposure are not adequately studied and no exposure standards exist.

Aspergillus niger. The 3rd most common Aspergillus fungi associated with disease and the most common of any Aspergillus species in nature due to it’s ability to grow on a wide variety of substrates. This species may cause a “fungal ball”, which is a condition where the fungus actively proliferates in the human lung, forming a ball. It does so without invading the lung tissue.

Stachybotrys chartarum (atra)

This group of moulds can thrive on water damaged, cellulose-rich material in buildings such as sheet rock, paper, ceiling tiles, insulation backing, wallpaper, etc. In the majority of cases where Stachybotrys is found indoors, water damage has gone unnoticed or ignored since it requires extended periods of time with increased levels of moisture for growth to occur. Stachybotrys is usually black and slimy in appearance. Events of water intrusion that are addressed quickly tends to support the growth of more xerophilic fungi such as Pencillium and Aspergillus.

Stachybotrys is another fungi that has the ability to produce mycotoxins, ones that are extremely toxic, suspected carcinogens, and immunosuppressive. Exposure to these mycotoxins can result through inhalation, ingestion, and dermal exposure. Symptoms of exposure include dermatitis, cough, rhinitis, nose bleeds, cold and flu-like symptoms, headache, general malaise, and fever.

Cladosporium spp.

These genera of mould are pigmented dark green to black in the front, and black on the reverse with a velvety to powdery texture. One of the most commonly isolated from indoor and outdoor air, Cladosporium spp. are found on decaying plants, woody plants, food, straw, soil, paint, textiles, and the surface of fiberglass duct liner in the interior of supply ducts.

There are over 30 species in the Cladosporium genus. The most common are C. elatum, C. herbarum, C. sphaerospermum, and C. cladosporioides. These fungi are the causative agents of skin lesions, keratitis, nail fungus, sinusitis, asthma, and pulmonary infections. Acute symptoms of exposure to Cladosporium are edema and bronchiospasms, and chronic exposure may lead to pulmonary emphysema.

Fusarium spp.

A common soil fungus and inhabitant on a wide array of plants, this fungi is often found in humidifiers and has been isolated from water-damaged carpets and a variety of other building materials. Human exposure may occur through ingestion of contaminated grains and possibly through the inhalation of spores. Fusarium spp. are frequently involved with eye, skin, and nail infections. More severely it can produce hemorrhagic syndrome (alimentary toxic aleukia) in humans which is characterized by nausea, vomiting, diarrhea, dermatitis, and extensive internal bleeding.

Several species can produce the trichothecene toxins which target the circulatory, alimentary, skin, and nervous systems. Vomitoxin is one such tricothecene mycotoxin that has been associated with outbreaks of acute gastrointestinal illness in humans. Zearalenone is another mycotoxin produced by Fusarium. It is similar in structure to the female sex hormone estrogen and targets the reproductive organs.

Penicillium spp.

These fungi are commonly found in soil, food, cellulose, grains, paint, carpet, wallpaper, interior fiberglass duct insulation, and decaying vegetation. Penicillium may cause hypersensitivity pneumonitis, asthma, and allergic alveolitis in susceptible individuals.

The genus Penicillium has several species. The most common ones include Penicillium chrysogenum, Penicillium citrinum, Penicillium janthinellum, Penicillium marneffei, and Penicillium purpurogenum.

This fungi has been isolated from patients with keratitis, ear infections, pneumonia, endocarditis, peritonitis, and urinary tract infections. Penicillium infections are most commonly exhibited in immunosuppressed individuals. For example, P. marneffei is a fungus abundant in Southeast Asia that typically infects patients with AIDS in this area. Infection with P.marneffei is acquired via inhalation and initially results in a pulmonary infection and then spreads to other areas of the body (lymphatic system, liver, spleen, and bones), and is often fatal. An indication of infection is the appearance of papules that resemble acne on the face, trunk, and extremities.

Penicillim spp. do have the ability to produce mycotoxins. The mycotoxin known as Ochratoxin A, which is nephrotoxic and carcinogenic, may be produced by Penicillium verrucosum. Verrucosidin is another mycotoxin produced by this fungus that exhibits neurotoxity. Penicillic acid is another mycotoxin that is nephrotoxic (causes kidney and liver damage).