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Reviewed by Dr John Pillinger, GP
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What is scabies?
Scabies is a contagious, intensely itchy, skin disease caused by a mite
(Sarcoptes scabiei), which is becoming increasingly common
for reasons that are unknown.
Scabies spreads from person to person usually by close
skin-to-skin contact or shared clothing or bed linen.
It is now accepted that mites can spread when a non-infected
person stands too close to an infected person. Mites are 0.1mm in
diameter.
How can you be infected with scabies?
Scabies is transferred when fertilised female mites gnaw their
way through the skin, usually within 30 minutes of mating, and create little passageways or burrows in the process.
In these passageways, they lay their eggs and die. Approximately
three weeks later the eggs hatch and a new generation of itch mites are ready
to reproduce. I t takes a hatched larva less than two weeks to become a mature adult with a life expectancy of up to six weeks.
It will also take about three weeks from the time of infection
before the itch starts. It will make the victim scratch the skin day and night
and can cause bleeding. The itching is due to an allergic reaction to the itch mites and their body fluids (ie, faeces and saliva).
Itch mites have their favourite areas of the body – the web
spaces of the fingers and toes; palms and soles; the wrists; the armpits; the
skin around the navel; and women's nipples and under the breasts.
How does the doctor make the diagnosis?
It is difficult for a doctor to diagnose scabies with 100 per
cent certainty unless a mite can be found and examined under a
microscope.
What are the prospects for the future?
Scabies will not disappear by itself; it requires treatment.
There is a risk of developing
eczema or other kinds
of chronic skin diseases.
How is scabies treated and what medicaton is used?
The treatment for scabies is simple and efficient. The medicines
used are
malathion liquid (eg Derbac-M, Prioderm or
Quellada-M)
or 5 per cent
permethrin dermal
cream (Lyclear dermal cream), all of which can be bought from pharmacies without a
prescription.
Medical advice should be sought before using malathion on
children under six months of age, and before using permethrin on children under
two years. In this age group the itch mites can affect the head and neck and the soles of the feet. An aqueous preparation of permethrin is the treatment of choice in children of all ages.
Malathion is applied to the whole body and washed off after 24
hours. Permethrin is applied to the whole body and washed off after 8 to 12
hours. Make sure you carefully follow the directions for use supplied with the
medicine.
When there is an outbreak of scabies, it is important that the
whole family is treated at the same time. Otherwise, the itch mites may return
after two to three weeks because they have survived on the skin of some of the
family and infected the others again.
Let people who have visited in the previous three weeks know
that they may be infected. It would be a shame if family and friends later
found they had scabies.
Also inform the children's schools. They need to take
precautions.
The itch of scabies may persist for some weeks after the
infection has been eradicated. This can be relieved by applying crotamiton (Eurax cream or
lotion), providing the skin has not been damaged by scratching.
Sedating antihistamines may also be useful to relieve
itching at night. Your pharmacist will be able to give you advice on the most
appropriate treatments for you and your family.
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Based on a text by Dr Flemming Andersen
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Last updated 06.10.2008
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