Download Management of localised viral skin infections

Management of localised
viral skin infections
Forum
Dermatology
Herpes simplex and varicella zoster are the two most common localised skin
conditions that present in general practice, writes David Buckley
Picture 1: Erythema multiforme rash with the typical target lesions on
the back post cold sores in a 46 year old
The two most common localised skin conditions caused
by viral infections are herpes simplex and varicella zoster.
Cold sores (herpes simplex virus type 1)
Herpes simplex virus (HSV) type 1 causes cold sores,
which are characterised by recurrent eruptions of a vesicular rash that crusts over and heals completely without
scarring over the course of one or two weeks. Although the
lips are the most common area affected (herpes simplex
labialis), cold sores can occur on any part of the body. The
only other eruption to repeatedly come up in the same area
would be a fixed drug eruption. This is very rare and not
usually vesicular.
The first attack of HSV type 1 is usually in childhood
and often asymptomatic. However, it may cause a painful
stomatitis in the mouth and lips that can cause difficulty
eating and swallowing (herpetic gingivostomatitis). This
usually resolves spontaneously within one to two weeks
without treatment.
Once infected, the virus will remain dormant and resistant to treatment in the basal root ganglion for the rest of the
patient’s life. It may erupt at any stage to cause the classical cold sores. There are many possible triggers for cold
sores (see Table 1), but often they can erupt for no particular reason. Treatment is difficult as usually the damage is
done as soon as the rash appears.
Avoidance of triggers is the best way to manage cold
sores but this is not always possible. Treatment with topical
antivirals such as acyclovir can be of some benefit but will
only work if the treatment is started at the earliest possible
stage; preferably at the tingling stage (if it occurs) before
the visible vesicles are seen. It has to be applied five times
a day for five days and for those with frequent attacks;
having a tube at home or in their handbag is useful so that
they can start treatment at the earliest possible time.
Picture 2. Postherpetic neuralgia with scarring in a 77-year-old woman
who had shingles three years ago
Table 1: Triggers for a HSV infection
• Minor trauma at the site of infection
• Febrile illness
• Excessive ultraviolet light
• Hormonal triggers (eg. with periods every month)
• Emotional stress (eg. with exams)
• Post-surgery on the face (eg. laser, deep chemical peel,
dermabrasion)
• Post-dental surgery
Once the vesicles have appeared it is questionable if
topical acyclovir will help. There are very few good clinical
trials on the value of topical acyclovir. It may well be that
a simple anti-inflammatory with a topical antibiotic may be
as effective or even more effective at this stage.
HSV type 1 can cause severe, extensive, painful, monomorphic vesicles and erosions with glands and a fever,
especially in patients who have a background of atopic
eczema (eczema herpeticum or Kaposi varicelliform eruption). For severe extensive infection, systemic antivirals
should help but again should be started at the earliest possible stage in an attack (see Table 2).
For patients with frequent recurrent severe attacks of cold
sores, prophylactic treatment with systemic antivirals may
be necessary. This can also be used for patients who are
at high risk of developing cold sores after procedures such
as chemotherapy, radiotherapy, laser treatment, chemical
peels, dermabrasion, etc.
When HSV type 1 affects the finger, it can cause a herpetic whitlow, which can sometimes be an occupational
hazard for dentists and dental assistants. This is why dentists should wear gloves for all oral examinations.
FORUM August 2013 31
Forum Dermatology
Table 2: Dosage of valaciclovir for viral infections in adults*
Immunocompetent
Immunosuppressed
HSV first attack
500mg BD x 10 days
1g BD x 10 days
HSV subsequent attack
500mg BD x 3-5 days
1g BD x 7 days
HSV prophylaxis
500mg OD x 6-12 months
(or 250 mg BD x 6-12 months)
500mg BD x 6-12 months
Herpes labialis (cold sores)
2,000 mg BD x 1 day
Varicella zoster virus (VZV)
1g TID x 7 days
1g TID until two days post-crusting of lesions
(minimum 7 days)
HSV = Herpes simplex virus; * Reduced dose for patients with renal impairment
Genital herpes (HSV type 2)
Genital herpes is a much less common but more serious
HSV infection, which is caused by a type 2 virus. Like cold
sores, the diagnosis can often be made clinically, with the
characteristic vesicular eruption recurring time and again
in the same area (penis or vagina) and healing without scaring. The eruption is painful and can take a few weeks to
heal. It is usually sexually transmitted and, like all STDs,
the patient should have a complete STD screen and contact tracing, which is probably best carried out in an STD
clinic, especially if it is a first attack. The diagnosis can
be confirmed by taking swabs using special viral swabs,
but it is only possible where there are fresh lesions. Treatment of genital herpes usually requires a systemic antiviral
treatment to be started as early as possible in an attack.
For those with frequent attacks, suppressive maintenance
treatment with an oral antiviral medication for six to 12
months may be helpful.
Patients are infectious during an attack and so should
avoid sex at this time. Childbirth during an attack of genital
herpes could possibly infect the new born child. Once the
lesions are fully healed, they are not usually infectious until
the next attack of herpes.
Erythema multiforme
This is a hypersensitivity reaction typified by a generalised rash that has the characteristic target lesions (see
Picture 1). HSV (cold sore) is the most common trigger.
This can sometimes be associated with blisters, erosions
and ulcers in the lips, mouth and genitalia, which can be
painful and debilitating. The rash should clear spontaneously after a few weeks but can recur with every attack of
cold sores in some patients. Treatment of erythema multiforme is usually with topical or oral steroids combined
with systemic antivirals for a severe attack. Prevention may
require treatment with long-term oral antivirals so as to prevent cold sores.
HSV may also trigger an attack of erythema nodosum
with the characteristic red, tender, maculopapular, nonscaly rash on the front of the shins and sometimes on the
forearms.
Chickenpox (varicella zoster)
Chickenpox (varicella zoster) is considered a harmless
childhood viral infection that occurs in most children.
It causes the typical generalised vesicular eruption and
mainly affects the face and trunk. It can be associated with
a low grade fever but most children recover spontaneously
without complications within one to two weeks. It has an
32 FORUM August 2013
Table 3: Indications for systemic
antivirals for shingles
• Patients more than 50 years of age
• History of the rash less than 72 hours (possibly seven
days in severe cases)
• Ophthalmic zoster
• Non-trunkal disease (eg. the face)
• Immunosuppressed patients
incubation period of 10 to 21 days. It is infectious from two
days before the appearance of the rash until all the vesicles
have crusted over, which usually takes five to 10 days. If a
person has a severe attack or is immunocompromised (diabetes, chemotherapy, leukaemia, HIV, etc), they should be
treated with systemic antivirals. The varicella virus can be
harmful to an unborn child, so children with chickenpox
should avoid contact with pregnant women if possible.
If a pregnant woman or an immunocompromised person
is exposed to a case of chickenpox and their immune status
is unknown, they should be considered for varicella zoster
immune globulin and systemic antivirals.
Chickenpox can leave small punched out scars, which
can be unsightly and permanent, particularly if they occur
on the face. Prevention of scarring may be helped by using
a topical anti-inflammatory with an antibiotic on the facial
lesions twice a day for seven to 14 days.
Shingles (herpes zoster)
Once chickenpox clears, the virus will remain dormant
in the anterior horn cells of the spinal cord. It can remain
dormant there for the rest of the patient’s life. It may be
reactivated spontaneously or by various triggers and when it
erupts it causes shingles. This can occur at any age but is
more common and more problematic in older people.
Shingles usually presents with the characteristic unilateral, vesicular or bullus eruption running in a dermatomal
distribution (eg. one side of the face, one side of the chest,
or down one arm or one leg). It can be painful and sore and
usually settles spontaneously in two to three weeks. Occasionally it can be very inflammatory and leave permanent
scars and chronic pain and tenderness in the area, which
lasts more than one month (see picture 2). This is known as
postherpetic neuralgia. It is more common in patients over
the age of 50.
There is some evidence that treating shingles with oral
antivirals at an early stage may be lessen the incidence
and severity of postherpetic neuralgia and so systemic
treatment should be considered for shingles, particularly in
those over the age of 50 once it can be started within 72
hours from the first appearance of the rash (see Table 3).
There is some limited evidence that systemic treatments
with antivirals may be effective even up to seven days after
the onset of the rash, particularly in the high risk groups.1
Shingles can be preceded by pain or discomfort in the
area involved for a few days before the rash appears. The
prodromal pain can be confused with many other conditions, depending on where the eruption occurs: For
example, if on the face, it may be confused with migraine;
on the chest – myocardial infarction, and on the abdomen
– cholecystitis or appendicitis, etc.
When shingles affects the ophthalmic branch of the facial
nerve, the eye could be in danger of corneal scarring and
so an ophthalmic opinion should be sought immediately.
The varicella zoster virus (VZV) may be shed from shingles
lesions and can cause chickenpox in a non-immune child or
adult. Despite popular myth, it is not possible to get shingles from another patient with shingles. However, clusters
of cases with shingles have been reported. It is suggested
that contact with someone with chickenpox or shingles may
cause one’s own virus to reactivate.
Postherpetic neuralgia
Postherpetic neuralgia causes neuropathic pain which
can be described as burning, shooting, itching or stabbing hypersensitivity in the area, which can last for more
than one month after an attack of shingles. This can be
a very painful and debilitating condition, particularly
when it occurs on the face. It does not usually respond to
standard analgesics such as paracetamol or non-steroidal
anti-inflammatories. Tramadol may be more effective in
some patients. Tricyclic antidepressants such as amitriptyline taken at night can be very helpful, particularly if there
is night pain or insomnia. The dose should be started at
10mg one or two hours before going to bed, and gradually
increased until the patient has a good night’s sleep without
drowsiness the following morning.
However, more specific treatments with antiepileptic
drugs, such as gabapentin or pregabalin, may be necessary.2 These should be started at a low dose and gradually
titrated up until a therapeutic response is obtained or side
effects ensured against. Topical treatments such as lidocaine patches are of limited value and are not practical
on the face. Topical capsaicin, which is derived from chilli
peppers, can act as a counterirritant, which may be of help
in some patients.
Transcutaneous electrical nerve stimulation (TENS) or
nerve blocks may be required in severe cases. Combining
treatments such as pregabalin, amitriptyline and capsaicin
cream may be tried, but at this stage the patient should
probably be referred to a pain clinic. In some countries
there are vaccines against chickenpox for children and
against shingles for people over the age of 50.
David Buckley is in practice in Tralee, Co Kerry
References
1. Forbes HJ et al. Prescription of antiviral therapy after herpes zoster in
general practice: who receives therapy? Br J Gen Pract 2012; 62: 632-633
2. Pawulska B. An update on the drug treatment of neuropathic pain (Part
II – Antiepileptics and other drugs). Drug and Therapeutics Bulletin 2012;
50(11): 126-129