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Dr
Colin Michie
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Should
you get rid of those house dust mites?
Folk suffering from allergic problems inevitably try to find and
remove anything in their surroundings which appear to make their
condition worse. House dust mites have become a popular target.
There are great temptations to invest in a new vacuum cleaner, flooring
and bedding in an attempt to remove house dust mites from homes.
But how useful are such measures? This subject is worth careful
consideration before spending substantial sums of money and effort.
Our
world teems with small creatures thriving on tiny particles of organic
matter. Not only plants and fungi, but small insects and mites exist
in their thousands within our homes. Most are barely visible, and
usually cause us no concern. In temperate homes with the advent
of central heating, increased humidity, together with vast food
traps in the fabric of carpets, these organisms tend to multiply
rapidly. They have no predators, and so little to limit their numbers.
One mite, the house-dust mite (Dermatophagoides pteronyssinus or
HDM) has been shown to be a source of allergens which can cause
eczema, asthma and rhinitis. This mite lives off human skin particles
and is particularly common in bedding, upholstered furniture and
carpets. Some of the proteins in the excrement of these creatures
can lead to a range of allergic reactions in susceptible humans.
So
should we all get rid of HDM? This question is difficult. In order
to reduce allergies in the average home it may be important to remove
sources of smoke, nitrogen dioxide (from gas flames), damp (which
encourages moulds) furry pets and larger insects such as cockroaches.
Obvious sources of pollen may have to be restricted in some way.
These measures will require the removal of old carpets and textiles
and the provision of good ventilation, perhaps with a filter. It
will also require regular cleaning of the home - never a popular
topic!
So
how does one specifically get rid of HDM? Ideally cleaning should
remove all mite particles and not only living mites. An initial
extensive steam cleaning of carpets and furnishings is recommended,
together with freezing then washing of soft toys. Several treatments
reduce further exposures to allergenic HDM particles at least ten-fold.
Chemical acaricides, air filters, or a combination of regular bedroom
laundry with specific bedding covers are effective. Regular vacuum
cleaning and dusting will be needed, as well as special attention
to soft toys. At present there are no comparative clinical studies
of vacuum cleaners or bedding products; consumer magazines may guide
you to find those products that have been formally tested.
Children
with asthma, eczema or rhinitis or adults suffering from rhinitis
will probably benefit from removing HDM. Sadly there are no clear
large studies showing similar benefits to adults with asthma or
eczema.
Surely
treating HDM should help everyone with an allergy? Several reasons
may explain why this is not the case. Firstly many with allergic
conditions are sensitive to many allergens. Secondly many suffer
deterioration in their conditions because of factors other than
allergens. For instance stress and nutrition can have dramatic effects
on all allergies, particularly those which have been established
for some time. Thirdly, as the underlying problem is allergy, the
sufferer may remove one allergen, only to react to another because
the underlying cause remains unchanged and untreated. Removal of
HDM for instance may be followed by an increased allergy to moulds.
Removing
house dust mites may be of value, but please discuss the problem
first with your medical advisors. Perhaps a formal consultation
and possibly a skin test would help you decide whether to invest
in mite eradication.
Useful
sources of further information:
National
Asthma Helpline 0845 701 0203
National
Asthma Campaign 0207 226 2260 Website: http://www.asthma.org.uk
Consumer
Association website: http://www.which.net
Information
sites relating to the relevance of House Dust Mites: http://www.jr2.ox.ac.uk/bandolier/band41/b41-4.html
http://www.niaid.nih.gov/publications/allergens/title.htm
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