Absidia
A zygomycete fungus. Reported to be allergenic. May cause mucorosis in
immune compromised individuals. The sites of infection are the lung, nasal
sinus, brain, eye and skin. Infection may have multiple sites.
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Acremonium(Cephalosporium)
Reported to be allergenic. Can produce a trichothecene toxin that is toxic
if ingested. It was the primary fungus identified in at least two houses
where the occupant complaints were nausea, vomiting and diarrhea. Asexual
state of Emericellopsis sp., Chaetomium sp., and
Nectripsis sp. It can produce mycetomas, infections of the cornea and
nails.
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Alternaria
Aw - 0.89. Conidia dimensions: 18-83 x 7-18 microns. A very common
allergen with an IgE mediated response. It is often found in carpets,
textiles and on horizontal surfaces in building interiors. Often found on
window frames. Outdoors it may be isolated from samples of soil, seeds and
plants. It is commonly found in outdoor samples. The large spore size, 20
- 200 microns in length and 7 - 18 microns in sizes, suggests that the
spores from these fungi will be deposited in the nose, mouth and upper
respiratory tract. It may be related to bakers' asthma. It has been
associated with hypersensitivity pneumonitis. The species Alternaria
alternata is capable of producing tenuazonic acid and other toxic
metabolites that may be associated with disease in humans or animals.
Common cause of extrinsic asthma (immediate-type hypersensitivity: type
I). Acute symptoms include edema and bronchiospasms; chronic cases may
develop pulmonary emphysema.
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Amerospore
A spherical or
oval single-celled fungal spore that is practically unidentifiable by
itself. Genera with this type of spore include, but are not
limited to, Aspergillus, Penicillium, and Trichoderma.
For example, Penicillium is easily identifiable when sampling
using culturing techniques. However, when sampling with non-culturing
techniques, such as spore traps or tape-lifts, the free spores with no
remnants of the fungal structure are indistinguishable from Aspergillus
and various other genera that also produce small round and oval spores
with little or no pigmentation. Due to this fact, Penicillium will often
be categorized on laboratory reports in an "amerospore" and/or "Aspergillus/Penicillium"
group.
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Arthrinium
Widespread
saprophyte found on decomposing plant material, particularly grasses, and
on soil. It is a white, fuzzy mold. It should be considered to be an
allergen. This fungus has also been documented in various subcutaneous
infections. No diseases related to toxic effects have been recorded to
date.
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Ascospore
A spore borne
in a special cell called an ascus. Spores of this type are reported to be
allergenic.
All ascomycetes, members of a group of fungi called Ascomycotina, have
this type of spore. The minute black dots on rotting wood and leaves or
the little cups on lichens are examples of ascomycetes; another is the
"truffle" mushroom.
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Aspergillus caesiellus
This
species is only occasionally pathogenic.
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Aspergillus candidus
Aw 0.75.
Conidia dimensions: 2.5-4 microns. Found in warm soils, grain and in the
secondary decay of vegetation. Associated with respiratory complaints in a
recent house investigation. Can produce the toxin petulin that may be
associated with disease in humans and other animals.
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Aspergillus carneus
This
species is only occasionally pathogenic.
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Aspergillus clavatus
Conidia
dimensions: 3-4.5 x 2.5-4.5 microns. Found in soils and animal manure.
Can produce the toxin petulin that may be associated with disease in
humans and other animals. This species is only occasionally pathogenic.
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Aspergillus deflectus
This
species is only occasionally pathogenic.
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Aspergillus flavus
Aw 0.78.
Conidia dimensions: 3-6 microns or 3-5 microns. It grows on moldy corn and
peanuts. It can be found in warm soil, foods and dairy products. Some
strains are capable of producing a group of mycotoxins- in the aflatoxin
group. Aflatoxins are known animal carcinogens. There is limited evidence
to suggest that this toxin is a human carcinogen. The toxin is poisonous
to humans by ingestion. It may also result in occupational disease via
inhalation. Experiments have indicated that it is teratogenic and
mutagenic. It is toxic to the liver. It is reported to be allergenic. Its
presence is associated with reports of asthma. It can be found in
water-damaged carpets. The production of the fungal toxin is dependent on
the growth conditions and on the substrate used as a food source. This
fungus is associated with aspergillosis of the lungs and/or disseminated
aspergillosis. This fungus is occasionally identified as the cause of
corneal, otomycotic and nasoorbital infections.
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Aspergillus fumigatus
Aw 0.82; Optimum> 0.97. Conidia dimensions: 2-3.5 microns. Considered a
human pathogen, this organism causes both allergic aspergillosis and
invasive aspergillosis (invasive aspergillosis usually affects individuals
who are immune compromised). It is commonly found outdoors on cereal
grains, in cool to warm soils, and in compost piles (even with
temperatures exceeding 40 degrees C).
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Aspergillus glaucus
Conidia
dimensions: 5-6.5 microns. Common outdoor fungus in the winter. It is
reported to be allergenic. This species is only occasionally pathogenic.
It can grow on leather. This fungus can grow at low moisture levels on
grains, sugary food products, meat and wool. The ascomycetous state is
Eurotium sp.
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Aspergillus nidulans
Aw 0.78.
Conidia dimensions: 2-4 microns. Found in mild to warm soils and on slowly
decaying plants. Can produce the mycotoxin sterigmatocystin. This toxin
has been shown to produce liver and kidney damage in lab animals. This
fungus is associated with aspergillosis of the lungs and/or disseminated
aspergillosis. This species is only occasionally pathogenic.
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Aspergillus
niger
Aw 0.77;
Optimum> 0.97. Conidia dimensions: 3.5 - 5 microns or 4 to 5 microns. Less
common cause of aspergillosis. It has a musty odor. It is commonly found
in the environment on textiles, in soils, grains, fruits and vegetables.
It has been reported to cause skin and pulmonary infections. It is a
common cause of fungal related ear infections, including otomycosis.
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Aspergillus ochraceus
Aw 0.77.
Conidia dimensions: 2.5 - 3 microns. Found in grains, soil and salted food
products. It is not usually associated with decaying vegetation. Can
produce a kidney toxin ochratoxin A that may produce ochratoxicosis in
humans. This is also known as Balkan nephropathy. The toxin is produced at
optimum growth conditions at 25 degrees C and high moisture conditions.
The ochratoxin may also be produced by other Aspergillus sp.
and Penicillium sp. Other toxins that can be produced by
this fungus include penicillic acid, xanthomegnin and viomellein. These
are all reported to be kidney and liver toxins.
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Aspergillus oryzae
This
species is only occasionally pathogenic.
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Aspergillus parasiticus
Some
strains are capable of producing a group of mycotoxins- in the aflatoxin
group. Aflatoxins are known animal carcinogens. There is limited evidence
to suggest that this toxin is a human carcinogen. The toxin is a poisonous
to humans by ingestion. Experiments have indicated that it is teratogenic
and mutagenic. It is toxic to the liver. The production of the fungal
toxin is dependent on the growth conditions and on the substrate used as a
food source.
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Aspergillus/Penicillium-Like
This category is included on laboratory analysis reports for air samples
containing certain free spores without other identifying structures.
The free spores of
Aspergillus and
Penicillium (and other genera with small, round or ovoid, and
colorless spores) are essentially indistinguishable, using standard
microscopic examination methods.
If required, cultured
specimens can provide additional characteristics that will enable
technicians to determine what genus is represented. If sporulating
structures are present, Aspergillus
is readily identifiable on tape samples. [Discovery of the
Aspergillus species requires
the culture of the fungus under different conditions of media, humidity,
and temperature. Identifying
Penicillium species is difficult, but, in some cases,
possible.]
These two allergenic
molds are among those most often found in contaminated buildings.
Aspergillus is represented by numerous species, many of which produce
toxic substances. It may be associated with symptoms such as sinusitis,
allergic bronchiopulmonary aspergillosis, and other allergic symptoms. As
if not to be outdone, Penicillium too is found in increased numbers
in interiors. Some of its many species produce toxic substances that can
cause allergic reactions, mucous membrane irritation, headaches, vomiting,
and diarrhea.
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Aspergillus penicilloides
Conidia
dimensions: 3-3.5 x 4-5 microns. Can grow in areas with low water
activity. It is found in house dust and food.
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Aspergillus restrictus
This
species is only occasionally pathogenic.
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Aspergillus
Aw 0.75 -
0.82. Reported to be allergenic. Members of this genus are reported to
cause ear infections. Many species produce mycotoxins that may be
associated with disease in humans and other animals. Toxin production is
dependent on the species or a strain within a species and on the food
source for the fungus. Some of these toxins have been found to be
carcinogenic in animal species. Several toxins are considered potential
human carcinogens. Common cause of extrinsic asthma (immediate-type
hypersensitivity: type I). Acute symptoms include edema and bronchiospasms;
chronic cases may develop pulmonary emphysema; may also be associated with
sinusitis, allergic bronchiopulmonary aspergillosis, and other allergic
symptoms.
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Aspergillus sydowi
This
species is only occasionally pathogenic.
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Aspergillus terreus
Aw 0.78.
Conidia dimensions: 1.8-2.4 microns or 2 - 2.5 microns. Aleurospores 6 - 7
microns in diameter are also produced. Found in warmer soil and in grains,
straw, cotton and decomposing vegetation. Can produce the toxin patulin
and citrinin that may be associated with disease in humans and other
animals. This fungus is associated with aspergillosis of the lungs and or
disseminated aspergillosis. Found as an isolate from otomycosis - ear
infection, and onychomycosis - infection of finger or toenails.
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Aspergillus ustus
This
species is only occasionally pathogenic.
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Aspergillus versicolor
Aw 0.78.
Conidia dimensions: 2-3.5 microns. Mostly in temperate zones, it is
commonly found in air, house dust, foods (including dairy products), soil,
hay, and cotton. It sometimes produces the mycotoxin "sterigmatocystin",
which can cause diarrhea and upset stomach, and is a possible carcinogen,
affecting the liver and kidneys. Various other toxins are associated with
A. versicolor, such
as aspercolorin, averufin, cyclopiazonic acid, and versicolorin.
Additionally, the volatile organic compound (VOC) "geosmin" is generated
by the action of this mold. Often an irritant to mucus membranes of humans
and pets, geosmin has a musty, earthy odor.
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Aureobasidium
Found in soil,
forest soils, fresh water, aerial portion of plants, fruit, marine estuary
sediments, wood. Allergen, Type I allergies (hay fever, asthma). Type III
hypersensitivity pneumonitis: "humidifier fever", "sauna taker's lung".
Growth indoors is widespread where moisture accumulates- especially
bathrooms and kitchens- on shower curtains, tile grout, windowsills,
textiles, liquid waste materials. Potential toxic production is not known.
Rare reports of: isolates from skin lesions, keratitis, spleen abscess in
a lymphoma patient, blood isolate from a leukemic patient.
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Basidiomycetes
Taxonomic designation for fungi of the subdivision "Basidiomycotina",
which includes mushrooms and puffballs. They produce spores that are
formed on the outside of a special cell, called the "basidium".
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Basidiospore
An exogenous sexual spore (meiospore) borne on a basidium. Or, a spore
from a basidiomycete (a member of Basidiomycetes). Many varieties are
reported to be allergenic.
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Bipolaris
A fungus with
large spores that could be expected to be deposited in the upper
respiratory tract. This fungus can produce the mycotoxin -
sterigmatocystin, which has been shown to produce liver and kidney damage
when ingested by laboratory animals.
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Blastomyces
Human
pathogen. The fungus is commonly found in soil. It is a dimorphic fungus
that has filamentous fungus when grown at 25 degrees C. and a yeast form
at 37 degrees C.
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Botrytis
Aw 0.93.
Conidia dimensions: 7-14 x 5-9 microns. It is parasitic on plants and soft
fruits. Found in soil and on house plants and vegetables, it is also known
as "gray mold". It causes leaf rot on grapes, strawberries, lettuce, etc.
It is a well-known allergen, producing asthma type symptoms in greenhouse
workers and the symptoms of "wine grower's lung".
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Candida
Part of the
normal flora of mouth and other mucous membranes in the body. Thrush and
other diseases caused by Candida albicans usually occur after
prolonged treatment with antibiotics or steroids. The environment is not a
likely source of exposure for this fungus. Cells from the organism are
usually not airborne. Reported to be allergenic.
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Cephalosporium
See
Acremonium
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Chaetomium
Large
ascomycetous fungus producing perithecia. It is found on a variety of
substrates containing cellulose, including paper and plant compost. It has
been found on paper in sheetrock. It can produce an Acremonium-like
state on fungal media. Varieties are considered allergenic and have been
associated with peritonitis, cutaneous lesions, and system mycosis.
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Cladosporium fulvum
(Fulvia fulva)
Conidia dimensions: 12-47 x 4-10 microns. It is found on the leaves of
tomatoes.
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Cladosporium herbarum
Aw 0.88.
Conidia dimensions: 5-23 x 3-8 microns. It is found on dead plants, woody
plants, food, straw, soil, paint and textiles.
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Cladosporium macrocarpum
Conidia
dimensions: 9-29 x 5-13 microns. It is found on dead plants, woody plants,
food, straw, soil, paint, and textiles.
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Cladosporium (Hormodendrum)
Aw 0.88; Aw
0.84. Most commonly identified outdoor fungus. The outdoor numbers are
reduced in the winter. The numbers are often high in the summer. Often
found indoors in numbers less than outdoor numbers. It is a common
allergen. Indoor Cladosporium sp. may be different than the species
identified outdoors. It is commonly found on the surface of fiberglass
duct liners in the interior of supply ducts. A wide variety of plants are
food sources for this fungus. It is found on dead plants, woody plants,
food, straw, soil, paint, and textiles. Produces greater than 10 antigens.
Antigens in commercial extracts are of variable quality and may degrade
within weeks of preparation. Common cause of extrinsic asthma
(immediate-type hypersensitivity: type I). Acute symptoms include skin
lesions, eye ulceration, mycosis (including onychomycosis, an infection of
the nails of the feet or hands) edema and bronchiospasms; chronic cases
may develop pulmonary emphysema.
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Cladosporium sphaerospermum
Conidia
dimensions: 3-4.5 microns. It is found as a secondary invader of plants,
food, soil, paint and textiles.
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Conidium
A thin-walled,
asexual spore borne exogenously on an often specialized hypha (conidiophore)
and is deciduous at maturity. (plural form: conidia.)
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Conidia, unidentified
These are mold
spores that do not show morphological characteristics that allow
identification. Because there are tens of thousands of types of fungi,
many fall into the "other" or "unknown" category. If they are present in
significant numbers, additional measures can be taken to identify them.
When spore counts are listed in the category: "Unidentified Conidia" their
numbers are considered "normal".
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Conidobolus
Can cause a
chronic inflammatory disease of the nasal mucosa (entomophthoromycosis).
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Cryptococcus neoformans
A
basidiomycetous encapsulated fungal organism found
worldwide, mainly around pigeon roosts and soil contaminated with decaying
pigeon or chicken droppings. It is generally accepted that the organism
enters the host by the respiratory route in the form of a dehydrated
haploid yeast or as basidiospores. Hematogenously spreading to
extrapulmonary tissues, its predilection for the brain means infected
persons usually contract meningoencephalitis, which can be fatal.
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Cryptostroma corticale
Conidia
dimensions: 4-6.5 x 3.5-4 microns. Found on the bark of maple and sycamore
trees and on stored logs.
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Cunninghamella
Can cause
disseminated and pulmonary infections in immune compromised hosts.
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Curvularia
Reported to be
allergenic and has been associated with allergic fungal sinusitis. It may
cause corneal infections, mycetoma, and infections in immune compromised
hosts.
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Dreschlera
Conidia
dimensions: 40-120 x 17-28 microns. Found on grasses, grains and decaying
food. It can occasionally cause a corneal infection of the eye.
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Epicoccum
Conidia
dimensions: 15-25 microns. A common allergen. It is found in plants, soil,
grains, textiles and paper products.
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Epidermophyton
Can cause
infections of skin (including ringworm) and nails.
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Fungus
Neither animals nor plants, these saprophytic and parasitic
spore-producing organisms rate a taxonomic kingdom of their own. Fungi
include molds, rusts, mildews, smuts, mushrooms, puffballs, and yeasts. It
is estimated that more than 1.5 million species of fungi exist.
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Fusarium solani
Aw 0.90.
Macroconidia dimensions: 27-52 x 4.4-6.8; Microcondia dimensions: 8-16 x
2-4 microns. Found in plants and soils. Can produce trichothecene toxins
that may be associated with disease in humans and animals.
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Fusarium
Aw 0.90. A
common soil fungus. It is found on a wide range of plants. It is often
found in humidifiers. Several species in this genus can produce potent
trichothecene toxins. The trichothecene (scirpene) toxin targets the
following systems: circulatory, alimentary, skin, and nervous. Produces
vomitoxin on grains during unusually damp growing conditions. Symptoms may
occur either through ingestion of contaminated grains or possibly
inhalation of spores. The genera can produce hemorrhagic syndrome in
humans (alimentary toxic aleukia). This is characterized by nausea,
vomiting, diarrhea, dermatitis, and extensive internal bleeding. Reported
to be allergenic. Frequently involved in eye, skin, and nail infections.
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Geotrichum
Aw 0.90.
Conidia dimensions: 6-12 x 3-6 microns. Aw 0.90. A common contaminant of
grains, fruits, dairy products, paper, textiles, soil, and water; often
present as part of the normal human flora. The species Geotrichum
candidum can cause a secondary infection (geotrichosis) in association
with tuberculosis. This rare disease can cause lesions of the skin,
bronchi, mouth, lung, and intestine.
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Gliocladium
A fungus that
is structurally similar to Penicillium sp. It is reported to be
allergenic.
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Helicomyces
A mitosporic
mold often encountered on decaying plant matter. The genus name prefix "helico"
is derived from the shape of the mold's microscopic structure; certain
filaments (sometimes the conidia) curve into a helical path.
Reported effects upon
human health in the indoor environment are not available at this time.
Scientists have shown
the interaction of Helicomyces roseus
with nitrogen-fixing bacteria to be a vital component of an effective soil
enriching system (where sugar cane litter is the decomposition target).
Helicomyces lilliputeus
has long been known as an important sewage treatment systems decomposer,
so it is not unexpected that other members of this genus have been
observed living on wood submerged in water.
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Helminthosporium
Reported to be
allergenic.
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Histoplasma
A fungus that
has filamentous growth at 25 degrees C. and yeast growth at 37 degrees C.
It is reported to be a human pathogen. It may be associated with birds.
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Humicula
Grows on
products with a high cellulose
content. These fungi are also found in soil and on plant debris.
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Hyaline mycelia
Mycelia
that are transparent, translucent, or colorless. If no reproductive
structures are present, identification is difficult. Often associated with
allergic symptoms.
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Memnoniella
A cellulolytic fungus that is very closely related to Stachybotrys
sp. Both fungi have a worldwide distribution and are often found together
and are commonly found in soil. Recent studies on mycotoxins revealed that
Memnoniella echinata can have a toxicity similar to that of some
isolates of Stachybotrys chartarum. Both produce varying amounts of
simple trichothecenes. Thus, it is suggested that Memnoniella sp.
should also be considered potentially dangerous in indoor air. The major
difference between the two fungi is that the conidia of Memnoniella
sp. are in long persistent chains while those of Stachybotrys are
aggregated in slimy heads. Also the aerodynamic diameter of Memnoniella
sp. conidia is smaller and it would be expected to have an even greater
potential to penetrate deep into lungs than the conidia of Stachybotrys
sp.
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Microsporum
Causes
ringworm in humans.
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Mold
Molds are a group of organisms that belong to the taxonomic
kingdom of Fungi. There
are over 20,000 species of mold. Molds reproduce by making spores. Mold
spores waft through the indoor and outdoor air continually. When mold
spores land on a damp spot indoors, they may begin growing and digesting
whatever they are growing on. Molds can grow on virtually any organic
substance, as long as moisture and oxygen are present.
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Monilia
Reported to be
allergenic. This fungus produces soft rot of tree fruits. Other members
produce a red bread mold. It is infrequently involved in corneal eye
infections.
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Mucor
Often found in
soil, dead plant material, horse dung, fruits and fruit juice. It is also
found in leather, meat, dairy products, animal hair, and jute. A
Zygomycetes fungus that may be allergenic (skin and bronchial tests). This
organism and other Zygomycetes will grow rapidly on most fungal media. May
cause mucorosis in immune compromised individuals. The sites of infection
are the lung, nasal sinus, brain, eye, and skin. Infection may have
multiple sites.
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Mycelium
A mass of interwoven hyphae (a hypha is a filamentous part of a fungus
that usually has several cells in linear succession with dividing walls in
between) that is often submerged in soil or organic matter or the tissues
of a host.
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Myxomycetes
A taxonomic
designation for fungi that are included in the category of "slime molds".
They're occasionally found indoors, but mainly reside in forested regions
on decaying logs, stumps, and dead leaves. Myxomycetes display
characteristics of fungi and protozoans. In favorable (wet)
conditions they exhibit motile, amoeba-like cells, usually bounded only by
a plasma membrane, that are variable in size and form. During dry spells,
they form a resting body (sclerotium) with dry, airborne spores. These
fungi are not known to produce toxins, but can cause hay fever and asthma.
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Nigrospora
Commonly found
in warm climates, this mold may be responsible for allergic reactions such
as hay fever and asthma. It is found on decaying plant material and in the
soil. It is not often found indoors.
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Oidium
The asexual
phase of Erysiphe sp. It is a plant pathogen causing powdery
mildews. It is very common on the leaves stems, and flowers of plants. The
health effects and allergenicity have not been studied. It does not grow
on non-living surfaces such as wood or drywall.
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Paecilomyces
Commonly found
in soil and dust; less frequently in air. P. variotii can cause
paecilomycosis. Linked to wood-trimmer's disease and humidifier associated
illnesses. They are reported to allergenic. Some members of this genus are
reported to cause pneumonia. It may produce arsine gas if growing on
arsenic substrate. This can occur on wallpapers covered with Paris green.
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Papulospora
These fungi are found in soil, textiles, decaying plants, manure, and
paper.
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Penicillium
Aw 0.78 -
0.88. A wide number of organisms have been placed in this genus.
Identification to species is difficult. Often found in aerosol samples.
Commonly found in soil, food, cellulose and grains. It is also found in
paint and compost piles. It may cause hypersensitivity pneumonitis,
allergic alveolitis in susceptible individuals. It is reported to be
allergenic (skin). It is commonly found in carpet, wallpaper, and in
interior fiberglass duct insulation. Some species can produce mycotoxins.
Common cause of extrinsic asthma (immediate-type hypersensitivity: type
I). Acute symptoms include edema and bronchiospasms; chronic cases may
develop pulmonary emphysema. It may also cause headaches, vomiting, and
diarrhea.
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Periconia
Found in soil,
blackened and dead herbaceous stems, leaf spots, grasses, rushes, and
sedges. Almost always associated with other fungi. Rarely found growing
indoors. Reportedly associated with a rare case of mycotic keratitis.
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Perithecium
A fruiting
body of a fungus in which some types of spores (including ascospores) are
produced. (plural form: perithecia)
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Peronospora
These species
are plant pathogens and the genus is one that causes downy mildews.
Peronospora is very common and is an obligate parasite (obligate
parasites cannot grow on non living environmental surfaces) found on
leaves, stems, flowers, and fruits of living higher plants. Peronospora
sp. may be identified in air on spore trap samples since spores have a
distinctive morphology. The spores may also be seen in dust as part of the
normal influx of outdoor microbial particles. As of this writing,
allergenicity has not been studied and no information is available
regarding health effects or toxicity.
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Phaeohyphomycosis
A hyphomycosis (infection by a mold of the taxonomic designation "Hyphomycetes")
in which the infiltrating microbes are usually of the mold family "Dematiaceae",
and are characterized by the coloring of their mycelium; the prefix "phaeo"
means "dusky-brown". Various forms of the disease involve different areas
of the body, such as the skin or respiratory tract. Intrusion of the mold
in the eye, brain, bone, or subcutaneous tissue typically occurs as a
result of trauma to the affected area.
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Phoma
A common
indoor air allergen that can cause hay fever, asthma, and a type of
hypersensitivity pneumonitis commonly called "shower curtain disease"
(shower surfaces being among those frequented by this fungal organism).
Phoma infections in humans
also have been reported; usually affecting the immunocompromised, they
include mycotic keratitis (where it refers to an infection of the skin)
and phaeohyphomycosis (see
phaeohyphomycosis).
For a positive
identification of this genus, the specimen must contain the pycnidia (a
round to pear-shaped fruiting structure containing conidia) to confirm the
presence of simple phialides (a cell from which conidia are extruded). A
cultured sample would provide these components. Colonies are rapid
growing, appear powdery to velvety, and exhibit many different colors.
This mold is known to grow on butter, rice, potatoes, paint (sometimes
seen as pink and purple spots on painted walls), cement, rubber, wood,
paper, and under linoleum. In nature, the species are found in soil,
manure, on fruit, dead plants, and as parasites on live plants.
Researchers have
discovered that when Phoma macrostoma
is sprinkled onto the soil in areas with no preexisting weeds, it acts as
an earth-friendly herbicide, inhibiting the ability of many broadleaf
plants (including dandelions) to produce chlorophyll; the young broadleaf
plants turn white and die while grass seems to be unaffected.
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Pithomyces
A native of
mostly tropical environments, it commonly grows on dead plants, soil,
wood, and especially the dead leaves and grasses of livestock fodder.
Pithomyces chartarum produces
sporidesmin (a piperazinedione), a mycotoxin known to cause animal liver
damage, and it causes facial eczema in cattle, sheep, and goats. For
humans, it is considered a possible allergen, and a potential infectious
agent in immunocompromised patients.
Not known to be prolific indoors, this mold can sometimes be found on
paper. It exhibits distinctive multi-celled brown conidia.
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Rhizomucor
The
Zygomycetous fungus is reported to be allergenic. It may cause mucorosis
in immune compromised individuals. It occupies a biological niche similar
to Mucor sp. It is often linked to occupational allergy. May cause
mucorosis in immune compromised individuals. The sites of infection are
the lung, nasal sinus, brain, eye, and skin. Infection may have multiple
sites.
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Rhizopus
The
Zygomycetous fungus is reported to be allergenic. It may cause mucorosis
in immune compromised individuals. It occupies a biological niche similar
to Mucor sp. It is often linked to occupational allergy. May cause
mucorosis in immune compromised individuals. The sites of infection are
the lung, nasal sinus, brain, eye, and skin. Infection may have multiple
sites.
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Rhodotorula
A reddish
yeast typically found in moist environments such as carpeting, cooling
coils, and drain pans. In some countries it is the most common yeast genus
identified in indoor air. This yeast has been reported to be allergenic.
Positive skin tests have been reported. It has colonized terminally ill
patients.
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Rusts
(and
smuts)
These fungi are associated with plant diseases. In the classification
scheme of the fungi, the smuts have much in common with the rusts, and
they are frequently discussed together. Both groups produce wind-borne,
resistant teliospores that serve as the basis for their classification and
their means of spread. Rusts usually attack vegetative regions (i.e.,
leaves and stems) of plants; smuts usually are associated with the
reproductive structures (seeds). They can cause hay fever and asthma.
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Saccharomyces
Reported to be
allergenic. Baker's yeast.
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Scopulariopsis
It may produce
arsine gas if growing on arsenic substrate. This can occur on wallpapers
covered with Paris green. It has been found growing on a wide variety of
materials including house dust. It is associated with type III allergy.
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Sepedonium
Most easily
recognized by the spores, which are colorless to yellow, spiny, round,
1-celled, and produced singly at the ends of short filaments. Sometimes
phialides of the Acremonium or Gabarnaudia type may also
occur. A few species of Mortierella, as well as the human pathogen
Histoplasma capsulatum, produce spores resembling those of
Sepedonium. Isolated from soil, but most commonly parasitized
mushrooms.
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Serpula lacrymans
Common
cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute
symptoms include edema and bronchiospasms; chronic cases may develop
pulmonary emphysema.
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Smuts
See
rusts.
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Spore
The means by which molds reproduce. Spores are microscopic (2-100
micrometers) and various shapes. Distribution can be accomplished by a
breeze, water droplet, or a person or animal passing by. They can even be
discharged by the mold (usually under moist conditions or high humidity).
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Sporobolomyces
Reported to be
allergenic.
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Sporothrix
The species
Sporothrix schenckii can cause sporotrichosis, but usually
only in individuals that are immune compromised. Sporotrichosis is a
chronic fungal infection that results when the mold enters the body where
the skin is damaged or via the lungs. If it reaches the bloodstream, it
can affect many other parts of the body.
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Sporotrichum
Reported to be
allergenic. Additionally, Sporotrichum
pruinosum has been observed in the respiratory secretions of
some human patients, indicating a possible ability to colonize the
bronchopulmonary pathways. This genus does not cause sporotrichosis (see
also
Sporothrix, for there is some taxonomic confusion
between these two genera).
Rarely found in cooler
regions, Sporotrichum is prevalent in warm-temperate and tropical
zones, and grows (rapidly) on soils, decaying plant matter, wet or rotting
wood, grasses, and landscaping mulch. Colonies may appear white,
rosy-beige, or orange, and have a velvety to granular texture.
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Stachybotrys
Aw - 0.94 ,
optimum Aw ->0.98. Several strains of this mold (S. atra, S. chartarum,
and S. alternans are synonymous) may produce macrocyclic
trichothecenes (one of which is Satratoxin H) that are poisonous by
inhalation. These mycotoxins, when present, are primarily associated with
the mold's spores.
Individuals with chronic exposure to Stachybotrys's toxins reported
cold and flu symptoms, sore throats, diarrhea, headaches, fatigue,
dermatitis, hair loss, general malaise, and psychological depression. For
infants, the toxins create a vulnerability to a serious condition called
pulmonary hemosiderosis (bleeding in the lungs) where severe bleeding can
result in coughing blood or nosebleeds, and low grade bleeding can cause
chronic coughs and congestion with anemia. People who unknowingly handled
material contaminated with this mold described symptoms of cough,
rhinitis, burning sensations of the mouth and nasal passages, and
cutaneous irritation at the point of contact, especially in areas of
abundant perspiration. The toxins produced by this mold will suppress the
immune system, affecting the lymphoid tissue and the bone marrow. Animals
injected with macrocyclic trichothecenes exhibited the following symptoms:
necrosis and hemorrhage within the brain, thymus, spleen, intestines,
lung, heart, lymph nodes, liver, and kidneys.
This is a dark-colored fungus that grows on building materials with a high
cellulose content and a low nitrogen content. It is slow growing when
compared to other common molds, and may not appear to compete well in
their presence. Yet, when moisture levels are high for prolonged periods,
Stachybotrys may gradually become the dominating genus (possibly
because of its yield of mycotoxins, which are believed to be directed
against other molds and bacteria). This organism is usually difficult to
find in indoor air samples unless it is physically disturbed, but when it
does appear it is an alert to find the source, as it will likely be found
growing in abundance. Its spores--which can be found in a gelatinous
mass--will die readily after release, but are still allergenic and can be
toxigenic. Areas with a relative humidity above 55%, and are subject to
temperature fluctuations, are ideal for toxin production.
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Stemphylium
This genus is
included in the taxonomic designation "Hyphomycetes". It is a known
allergen, causing Type I allergies (examples: hay fever, asthma).
Phaeohyphomycotic sinusitis has been reported in connection with this
mold. (See
phaeohyphomycosis.)
Existing mainly in the
temperate northern hemisphere, it can be found in soil, moist wood or
cellulose materials, on decomposing plants, and as pathogens on living
plants (leaf spots are one example). Colonies grow rapidly, and appear
velvety to cottony in texture; coloring is light brown or olive green to
black. Though it is rare to find indoor colonization, it has been found in
dust that is transferred in from outside, including dust on air filters.
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Syncephalastrum
Can cause a
respiratory infection characterized by a solid intracaitary fungal ball.
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Torula
Found outdoors
in air, soil, on dead vegetation, wood, and grasses. Also found indoors on
cellulosic materials. Reported to be allergenic and may cause hay fever
and asthma.
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Trichoderma
It is commonly
found in soil, dead trees, pine needles, paper, and unglazed ceramics. It
often will grow on other fungi. It produces antibiotics that are toxic to
humans. It has been reported to be allergenic. It readily degrades
cellulose.
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Trichophyton
Can cause
ringworm, athlete's foot, jock itch, and other infections of the skin,
nail, beard and scalp. Reported to be allergenic. Found on soil and skin.
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Trichothecium
Aw 0.90.
Conidia dimensions: 12-23 x 8-10 microns. Found in decomposing vegetation,
soil, corn seeds, and in flour. The species Trichothecium roseum
can produce a trichothecene toxin that may be associated with disease in
humans and other animals. Reported to be allergenic.
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Tritirachium
Reported to be
allergenic.
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Ulocladium
Aw 0.89. This
mold is reported to be a major allergen, capable of causing hay fever and
asthma. It is also known to rarely cause subcutaneous infections. The
University of Adelaide, Australia, categorizes this microbe in the
classification group "Dematiaceous Hyphomycetes", which includes it as a
possible causative agent of phaeohyphomycosis (see
phaeohyphomycosis).
Widely distributed in
nature and considered a saprobe (weak parasite), some of its growth sites
are soil, grasses, dead or dying plants (mainly herbaceous vegetation),
manure, and compost. In interior environments it has been found on paper,
painted surfaces, gypsum board, textiles, jute, straw materials, carpets,
cellulose building materials (including wood), and in dust and air
samples. Colonies are moderately fast growing, usually appearing
olive-brown (or rusty-brown) to black (or grayish), with a texture that is
granular to velvety.
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Verticillium
Conidia
dimensions: 2.3-10 x 1-2.6 microns. Found in decaying vegetation, on
straw, soil and arthropods. A rare cause of corneal infections.
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Wallemia
Aw 0.75.
Conidia dimensions: 2.5-3.5 microns. Found in sugary foods, salted meats,
dairy products, textiles, soil, hay and fruits.
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Yeast
Various yeasts
are commonly identified on air samples. Some yeasts are reported to be
allergenic. They may cause problems if a person has had previous exposure
and developed a hypersensitivity. Yeasts may be allergenic to susceptible
individuals when present in sufficient concentrations.
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