Edition 16 - November, 2004
Edition 16 - November, 2004 |
Allergy to moulds |
The air we breathe contains many micro-organisms, among which fungi are often the most varied and, the most numerous. they sometimes cause cutaneous and respiratory pathologies, mainly allergic reactions.
A wide range of allergic reactions can occur: rhinitis, dermatitis, allergic
bronchitis, asthma, allergic broncho-pulmonary mycoses, and hypersensitivity
reactions. moreover, various components of the fungal wall and several of the
metabolites produced during their growth have toxic or irritant properties,
which may activate or aggravate the allergic reaction.
Five to fifteen% of the population sufferingfrom respiratory allergy have been sensitizedto one or several moulds. Exposureof young children to moulds and their metabolitesmay have a “stimulating” effect onthe onset of later allergies.
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Ever since the first petroleum crisis in the
early 1970s, allergic complaints correlated
with the home environment have been
constantly increasing. Domestic moulds
grow abundantly in moist, poorly ventilated
and dark places, so cellars have always been
a preferred site for various species of Penicilliumand Aspergillus. However, the fungal
flora of dwellings has greatly diversified
over the last 20 years. Excessive insulation
after the petroleum crisis has markedly favoured
condensation areas (cold bridges),
from cellars to attics, which rapidly become
sites of intensive mycelial growth. Accompanying
lifestyle changes have led increasingly
to the production and accumulation of moisture in the home (frequent showers,
new cooking methods, inadequate airing of
bedrooms, etc.).
Figure 2 outlines the incidence in Belgium
of isolated moulds in homes of patients
complaining of the exacerbation of allergic
problems in their homes. More than 90%
of those houses were contaminated by the
genera Penicillium, Cladosporium and Aspergillus(more than 120 different species).
C. sphaerospermum infiltrated 60% of the homes and was responsible for some of the
highest levels of contamination, particularly
in bedrooms and bathrooms (several
100 spores/m³ of air). This species is often
found on window frames together with
Aureobasidium pullulans, Phoma sp., and
Acremonium strictum and various species
of yeasts and Fusarium. While C. herbarum,
a phytopathogen, does not grow in houses,
large numbers of spores enter through windows
and doors mainly during the summer
months.
Aspergillus versicolor, Penicillium chrysogenum,
Penicillium aurantiogriseum, Penicillium
spinulosum, Penicillium brevicompactum,
Chaetomium globosum, Stachybotrys
chartarum, Acremonium strictum, and Alternaria
alternata are other species that are
often found in great abundance on the walls
of bedrooms, living rooms, and kitchens.
Finally, mattresses also constitute an important
reservoir for moulds (see the list of
species) with concentrations of 103 to 107
spores per gram of dust! Like mites, moulds
thrive on the poor ventilation and excessive
dampness of the modern bedroom.
Many workers are exposed to large quantities
of fungal spores in the workplace. Hypersensitivity
pneumopathologies of fungal
origin have often been given the name of
the profession (for example, cheesemaker’s
disease and mushroom grower’s disease; cf.
Figure 3), and are generally associated with
a restricted number of fungal species. The
development of biotechnology has revealed
the extraordinary capacity of moulds to
undergo transformation, biosynthesis and
bioconversion. Many techniques using
yeasts and moulds have been devised and
are used industrially to produce enzymes,
organic acids, and vitamins, and yeasts are
used to degrade fats and oil wastes and so
on. In each case, the incidence of allergies
among the workers has rapidly increased.
In parallel, the list of allergenic species is
becoming ever longer.
In rural environments, particularly at harvest
time, the handling of contaminated
plants in the fields may result in asthmatic reactions. Stocking moist crops or
storing them in ill-ventilated barns may
induce the development of other species. Aspergillus fumigatus is well-known
among allergologists: when damp hay is
worked, clouds of spores are released and
inhaled by the farmers, provoking cases
of hypersensitivity. The same occurs in
dustmen when waste is stocked in closed
containers for too long and for compost
makers.
Mushroom growers may be exposed to
huge quantities of spores released by the
basidiomycetes they cultivate, and the
culture substrate is sometimes also contaminated
by allergenic moulds. Cheese
washers inhale mostly species of Penicillium:
P. casei, P. camembertii and Penicillium
roquefortii. Workers who handle
traditional salami inhale Penicillium nalgiovense,
and those who handle chorizotype
sausages inhale Monascus ruber.
Workers who toss germinating barley in
malteries inhale Aspergillus clavatus.
In industrial and city environments, buildings
and industries equipped with heating, ventilation,
and air conditioning equipment (HVAC)
are generally provided with indoor air of good
microbiological quality. However, poorly maintained
humidification containers, air ducts,
and filters may become contaminated and release
into the air allergens that cause dermatitis,
rhinitis, asthma, or even hypersensitivity.
BCCM/IHEM holds more than a thousand
strains isolated from the air and the environment
of allergic patients as well as reference
strains routinely used in allergology. Most
strains from the BCCM/IHEM collection can
be cultured and supplied as fungal raw material
on special request: the prices are determined
in function of the species and the
quantity ordered
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