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 Viral
Warts/Verrucae
Definition
Viral warts are an infection of the surface layer of the skin
(epidermis) caused by a virus. The virus which causes warts
(verrucae) in humans is called the human papilloma virus of
which there are many different variants.
Incidence, Age and Sex
Viral warts (verrucae) occur more commonly in children than
in adults. The majority of adults have been exposed to the
virus responsible for warts (verrucae) as a child and as a
result may have formed their own immunity (antibodies) to
the virus without necessarily having clinically visible apparent
warts (verrucae) at any stage on their skin. In practice 95%
of adults develop immunity to the wart virus.
Causes and Preventions
Viral warts (verrucae) are caused by external contact occurring
with the human papilloma virus. As an electron microscope
is required to visualize the human papilloma virus it is therefore
not visible to the naked eye. Therefore in practice where
the wart virus is acquired from usually remains a mystery.
It takes time for the virus to multiply within the skin, for
it to enter the skin cells, and for a visible wart (verruca)
to become apparent. The virus is acquired from external contact
and does not pass internally, and is not passed through the
blood stream. In practice therefore it can be passed from
hand to hand contact or be acquired from communal changing
facilities, for example swimming baths where the risks of
verrucae are increased.
As it may take several months for a visible wart (verruca)
to become apparent, restrictions on that individual from coming
in contact with other people are worthless. This is because
when the virus enters the skin cells, the virus becomes locked
up within the individual cells causing an increased rate of
cell turnover in the surface of the skin with the typical
wart (verruca) appearing above the surface. The virus at this
stage is locked up within the cells and at a deeper level
and therefore poses very little risk to any individuals coming
in contact with them. Before the wart (verruca) becomes apparent
then some shedding of virus may occur resulting in the potential
for infection to occur to other individuals but this is at
the stage when the skin looks normal. Therefore no restriction
should ever be placed upon an individual with warts or verrucae
from engaging in any communal activities which include swimming.
Signs and Symptoms
A common wart is usually easily recognizable from its raised
up craggy appearance above the skin. These commonly occur
on the hands but can occur at other sites. When they occur
on the face they may have a long stringy appearance (called
a filiform wart). When verrucae occur on the feet they may
be obvious or sometimes appear as a hard callus. These may
be painful when they are on the feet because of pressure through
the hard skin impinges on the underlying nerves.
Warts on the hands tend not to have any associated discomfort
unless the skin heats up, becomes dry and then splits and
cracks which can result in subsequent discomfort.
Complications of the Disorder.
There are no complications to be concerned about in respect
of common warts or verrucae. The main problem with warts (verrucae)
is their social embarrassment and how other people react to
the cosmetic appearance of a wart when there realistically
is minimal risk involved with any contact.
Tests
No specific tests are indicated for cases of viral warts (verrucae).
Treatment
No exclusion is required of sufferers of viral warts (verrucae).
The condition is self-limiting, usually spontaneously improving
with the passage of time. This however is dependent upon the
age of an individual. In practice sufferers who are under
the age of 20 will usually expect to see spontaneous involution
occurring within a 2 year period on average. This means that
some people are quicker and some people are slower. Between
the ages of 20 and 30 it will take on average 3 years for
spontaneous involution to occur. Above the age of 30 it can
run a more unpredictable course and periods of 5, 10 years
or even longer may pass before spontaneous involution does
occur. This is usually because an adult’s immune system
may not be as effective as a child’s immune system.
It should therefore always be remembered that in young children
and teenagers that the condition will disappear spontaneously
with no scars remaining. If the condition is allowed to disappear
spontaneously this is due to the acquisition of antibodies
against the human wart papilloma virus. Once these antibodies
have been acquired then second infections rarely occur. Therefore,
encouragement should always be given to allow nature to run
its course.
If active treatment however is considered then in children
and young adults, improving the appearance by regularly paring
with a pumice stone, emery board etc. can help to flatten
the lesions if this is undertaken on a daily basis. If the
lesions are kept flat then the appearance is improved, there
is less tendency for splitting and cracking to occur, and
less pain from pressure when verrucae are involved.
This is also the principle of using so-called wart paints.
Wart paints are aimed primarily at peeling at the surface
of the skin, causing flattening to occur but rarely do the
wart paints adequately penetrate into the skin to have any
real effect on killing off the wart virus. The usual reason
that warts disappear in individuals who are using wart paints
is that the individual’s antibodies have switched on
which then dispose of the virus. There is a large range of
wart paints available over the counter and on prescription.
More aggressive treatment can be considered but this is really
only justified in adults when the condition is likely to run
a long extended course.
Surgical intervention (excision) should in practice never
be considered because any virus remaining could seed itself
back into the site of the scar resulting in an almost immediate
recurrence.
One of the most common treatments used for aggressive treatment
of viral warts (verrucae) is cryotherapy which uses liquid
nitrogen as a source for freezing. In effect liquid nitrogen
can cause localized frost bite of the skin from intense freezing
cold. Liquid nitrogen if used correctly kills off the cells
containing the virus but does not actually kill the virus
off itself. Therefore it has to be used to ensure that the
depth of freezing is adequate to destroy the roots of the
wart (verruca) itself. This may required extended freezing
time and possibly repeat freezing after a few minutes of thawing
to ensure adequate cell damage. This will result in blistering
of the skin occurring. In practice if blistering does not
occur after cryotherapy the chances of cryotherapy working
are minimal. Blistering of the skin with cryotherapy can result
in a slow healing area and on dark skin can permanently damage
the skin pigment. In other areas caution is required with
cryotherapy, particularly around the nail folds caution is
required because of the potential of liquid nitrogen to permanently
damage any nail plate.
An alternative treatment for warts is cauterization. This
involves using the equivalent of a red hot medical soldering
iron to physically destroy the wart itself and to burn over
the base of the wart. This then results in a small area which
heals up like a bad graze. There is always a risk with cauterization
of scarring occurring. Cauterization may be useful with warts
on the face, as the face with its good blood supply is more
difficult to freeze with liquid nitrogen. The results of cauterization
can be immediate whereas cryotherapy takes at least 4 weeks
to know whether or not it has worked.
Long filiform (stringy) warts occurring on the face of children
are best treated by trimming the long dead skin with a sharp
pair of scissors in the same way that individuals cut toe
nails. By keeping these trimmed the appearance can be improved
and eventually spontaneous resolution will occur.
Many other treatments have been claimed to be of benefit for
warts and verrucae. There have been recent reports of laser
treatment using a pulsed tunable dye laser being of benefit.
By shutting down the blood supply to a wart then individual
warts may then shed off following laser treatment. This may
be of benefit for a few stubborn warts which have not responded
to conventional treatment or have persisted beyond the normal
time scale expected for a viral wart.
Other experimental treatments including injecting anti-cancer
drugs into viral warts can be considered in some instances
but this is under the supervision of a hospital consultant
dermatologist.
Outcome
It should always be remembered that for the majority of individuals
viral warts (verrucae) are a self-limiting condition. Nature
is therefore the best healer. Active treatment can be considered
if there are problems with a particular wart or if it is not
resolving within the normal time scale as discussed above.
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