Viral Skin Infections
Herpes simplex
Infection with herpes simplex virus (a DNA virus) is one of the most
prevalent
infections
of
humans
worldwide.
There
are
two
immunologically distinct viruses: herpes simplex virus type 1 (orofacial
type) and herpes simplex virus type 2 (genital type), although there may
be overlap between disease manifestations.
HSV infections have two phases: primary infection phase and the
secondary recurrent infections phase.
Clinically, the first episode may
represent a true primary infection or a recurrence
Both HSV1 and HSV2 reside latent in the sensory ganglion, after
primary infection, undetected by the host immune mechanisms
Spread is by respiratory droplets, direct contact with the active lesion or
contact with the virus-containing secretions (saliva or genital
secretions). Asymptomatic patients shed the virus 100-1000 times less
than the symptomatics with active lesions.
Orolabial herpes simplex
Primary infection: occurs most commonly in children between ages 1-5
years and is usually subclinical. In about 10% of the cases, acute
gingivostomatitis and pharyngitis occurs. Although most cases are mild,
some are severe. Sore throat and fever may precede the onset of
painful vesicles occurring any where in the oral cavity or on the face.
The vesicles rapidly coalesce and erode with a white-yellow superficial
purulent exudate. Tender cervical lymphadenopathy develops and fever
subsides in 3-5 days but oral pain and ersions gone in 2 weeks.
Recurrent infection: Recurrences arise in 30-50% of cases. Triggers
may be fever, URTIs, UVL exposure, trauma, menstruation, stress, or
no evident reason. Recurrent infections appear most frequently on the
face near the mouth. They are characterized by smaller size of vesicles,
close grouping and the usual absence of constitutional symptoms.
Itching and burning precedes the development of the closely grouped
vesicles on an inflammed base that usually become purulent and
crusted before healing in 7-10 days without scarring.
Genital herpes simplex
Primary infection: Occurs mostly after puberty and is sexually
transmitted causing multiple painful genital or perianal blisters that
rapidly ulcerate. Transmission is most frequently during periods of
asymptomatic shedding. Occasionally, an infant contracts HSV-2 in
utero or by direct contact in the birth canal.
Recurrent infection: is fairly common (occurs in 95% of cases)
producing clusters of small vesicles resulting in non-indurated ulcers on
penis (glans or shaft), labia, vagina, or cervix. Asymptomatic shedding
can occur.
Herpes simplex may appear on any skin surface (e.g. buttock and
lumbosacral region). Fingertip involvement (herpetic whitlow) occurs
most commonly in healthcare professionals.
Investigations:
None are usually needed, but Tzank smears (Multinucleated giant cells
present in scraping of mucocutaneous erosions), flourescent antibody
test, viral culture, polymerase chain reaction (PCR), or skin biopsy may
be needed in doubtful cases.
Complications:
1 Secondary bacterial infection:
2 Eczema herpeticum: patients with atopic dermatitis are particularly
susceptible.
3 Erythema multiforme: may regularly follow recurrent herpes simplex
infections.
4 Recurrent dendritic ulcers: leading to corneal scarring.
5 Disseminated herpes simplex: resulting in severe illness in newborns,
or immunosuppressed patients.
6 Herpes encephalitis and meningitis can occur without any cutaneous
clue.
Management:
The disease is usually self limited and no much interference is required.
A cool water compress or surgical spirit dabbing and topical
antibacterial cream is sufficient for occasional mild recurrent attacks.
More severe and frequent attacks may require the application of
acyclovir cream (5 times daily for 5 days) with the first sign of
recurrence. Oral acyclovir (200mg 5 times daily for 5 days) is more
effective and can be used for widespread or systemic involvement.
Famciclovir and valcyclovir require fewer doses per day. Supportive
therapy is required when indicated.
Herpes Zoster (Shingles)
Varicella (chickenpox) and herpes zoster (shingles) both are produced
by the same virus, the varicella-zoster virus (VZV). Varicella results
from contact of a nonimmune person with this virus, whereas herpes
zoster occurs in persons who have had previous varicella, either clinical
or subclinical. As a rule, herpes zoster is caused by reactivation of a
latent infection in either a spinal or a cranial sensory ganglion. On
reactivation, the virus spreads from the ganglion along the
corresponding sensory nerve or nerves to the skin.
Herpes zoster occurs largely in adults, particularly old age, but it can
occur in children (usually with a mild course). Pain, tenderness,
paresthesia, generally localized to the dermatome, precedes the
eruption by 4-5 days and may be accompanied by fever, headache, and
malaise. Regional lymphadenopathy may be present. The pain may
simulate pleurisy, MI, renal pain, abdominal disease, or migraine
headache. Eruption consists of grouped vesicles on (erythematous and
edematous) inflammatory bases, arranged along the course of a
sensory nerve (in an interrupted or a continuous band). Successive
crops continue to appear for 7days. Vesicles either umblicate or rupture
before forming a crust, which fall off in 2-3 weeks. Zoster is
characteristically unilateral, dermatomal. Thoracic region is affected in
2/3 of cases. It is possible, though very unusual, to have two or three
episodes in life time.
Cranial nerve syndromes: these are special variants of herpes zoster.
herpes zoster ophthalmicus: involvement of the ophthalmic division of
trigeminal nerve can lead to corneal ulcer and scarring. Ramsay Hunt
syndrome: when the geniculate ganglia are affected causing unilateral
facial nerve palsy accompanied by vesicular rash on the ear or in the
mouth with unilateral loss of taste sensation on the anterior 2/3 of the
tongue.
Complications
1 Secondary bacterial infection of skin lesions is common.
2 Postherpetic neuralgia: persistant neurolgic pain, after the acute
episode is over, is most common in the elderly.
3 Meningoencephalitis, visceral involvement (pneumonitis, hepatitis,
etc), or cutaneous dissemination may occur in immunosupressed
patients.
4 Corneal ulcer and in herpes zoster ophthalmicus.
5 Motor nerve weakness is uncommon.
Treatment:
Symptomatic with rest, analgesics and bland applications such as
calamin. Secondary bacterial infection should be treated appropriately.
Systemic antiviral therapy should be given to all patients if diagnosed in
the early stage (within the first 5 days) of the disease. Oral acyclovir
(800 mg 5 times daily for 7 days). Famciclovir and valcyclovir are as
effective and all are safe drugs. For established postherpetic neuralgia,
a trial of systemic carbamazapine, gabapentin, or amitryptiline may be
worthwhile. Topical capsiacin cream or regional infiltration with lidocaine
may be tried.
Viral wart
Warts are caused by the human papillomavirus which is a DNA virus
that infect squamous epithelia causing cell proliferation. To date, more
than 150 different types of HPVs have been cloned and characterized,
and new types are discovered each year, and these vary in their
specificity for different anatomical site. Warts can occur at any age, but
are rare in infancy and early childhood. Incidence increase at school
age and reach peak in adolescence and early adulthood. Spread is by
direct and indirect contact. Impairment of the epithelial barrier function
by trauma (including mild abrasions), maceration, or both predispose to
inoculation of the virus.
The traditional clinical classification of (HPV) infection is based on
appearance and location. Although there is a significant variation in
clinical morphology, all represent infection by HPV. Clinical patterns
include:
(1) Common wart (Verruca vulgaris)
These are circumscribed, firm, elevated papules with papillomatous
(“verrucous”) hyperkeratotic surfaces. They occur singly or in groups.
Generally, they are associated with little or no tenderness. and occur
most commonly on the dorsal aspects of the fingers and hands. Filiform
warts, variants of Common wart, show threadlike, keratinous projections
arising from horny bases. They are most commonly found on the face
and scalp.
(2) Plantar wart (verruca plantaris):
This type usually presents by pain. Painful, flattened, thick, deeply
embedded tender papules with rough keratotic surface occur on the
sole of the foot, usually against pressure points. They may be single or
multiple. Usually are covered with a thick callus and when the callus is
removed with a scalpel, the wart becomes apparent.
DDx: corn
Wart
Corn
Anywhere on planter surface
over bony prominences
Site:
disrupted
normal
Skin lines
On lateral pressure also
On direct pressure only
Pain
Reveales warty tissue
(punctate hemorragic spots from
thrombosed capillaries(
Reveals normal skin
(stratum corneum(
Paring
(3) Plane wart (verruca plana):
are slightly elevated, flat, smooth papules. Usually skin colored but may
pigmented. The face and the dorsa of the hands are affected most
commonly. No. range from f
ew to 100s. Koebner’s phenomena (i.e
occurrence of new lesions at trauma sites) is positive, like in the
common wart.
(4) Anogenital wart (Condylomata acuminata):
can occur on the penis, on the female genitals, and in the anal region.
The skin lesions consist of fairly soft, not hyperkeratitic , verrucous
papules
that
occasionally
coalesce
into
papillomatous
often
pedunculated cauliflower-like masses with a moist macerated vascular
surface. They may coalesce to form huge lesions causing discomfort
and irritation. Vaginal and anorectal mucosae may be affected and
lesions are flatter on mucosal surfaces. It is transmitted both sexually
(mostly) and non sexually.
DDx: condylomata lata: seen in syphilis, lesions are oval, slightly raised,
flatter, greyer and less well defined. Look for other signs of secondary
syphilis and carry out serological tests.
Treatment
Routine treatment of every wart is unnecessary. Explain that self
resolution may occur. Whatever method used, there may be
recurrences and failures. So many modalities are available and all
depend on destruction of the tissue infected with the virus.
Topical applications:
Keratolytics (salicylic acid and lactic acid) for common and plantar
warts. Caustics (TCA) may also be used. Topical retinoic acid
application for 2-3 weeks may clear plane warts. Podophyllin paint is
used for anogenital warts. Imiquimod cream is also effective.
Surgical methods:
Cryosurgery: light cryosurgery with liquid nitrogen freezing the wart is
quite effective but painful. Electrosurgery: More effective than
cryosurgery, but also associated with a greater chance of scarring.
Local anesthesia is required. Surgery: by curettage. Surgical excision of
cutaneous HPV infections is not indicated in that these lesions are
epidermal infections. Laser Surgery: Effective for recalcitrant warts.
Molluscum contagiosum
Common (contagious) disease caused by DNA pox virus (molluscum
contagiosum virus (MCV)) afflicts both children and adults. The
incubation period is 2-6 weeks and spread occurs by direct contact
(including sexual transmission) or indirectly by contaminated fomites.
Lesions present as shiny, pearly white, dome shaped, sessile papules
with a smooth surface and characteristic central umbilication. A white
cheesy material may be expressed from the central punctum on
squeezing the lesion. Spontaneous involution may occur, during which,
there may be mild inflammation and tenderness. Same treatment
outlines as common warts are applied. Lesions can be squeezed with
forceps expressing cheesy material.
Orf (ecthyma contagiosum)
Parapox virus infection spread from sheep or goats to contact persons.
The infected animals have a stomatitis, with crusted lesions on the lips
and in the mouth. After an incubation period of 3 to 7 days, patient
develop one to three (rarely more) painful firm, dome-shaped nodules ,
several centimeters in diameter with an erythematous periphery, usually
on the hands or occasionally elsewhere as a result of autoinoculation.
They may trigger erythema multiforme or lymphangitis. Heal without
scarring over weeks. No active treatment is required, but topical
antibiotic to prevent secondary bacterial infection
Hand, Foot, and Mouth disease
As the name suggests, is an infection causing lesions on the hands/feet
and in the mouth. Commonly associated with Coxsackievirus A and can
affect children and adults. The virus is highly contagious with a short
incubation period of 3
–6 days. Young children in particular present with
fever, headache and malaise alongside the rash. The characteristic
rash consists of erythema surrounding yellow-grey vesicles on
palms/soles and lips. Rarely, a more generalized eruption develops.
The condition lasts up to a week. No specific treatment
.