viral skin anfections

dermatology dr. hussein a. al-sultany


viral skin infections

herpesviruses

herpesviruses belong to herpesviridae which is a large family of dna viruses.
there are eight distinct viruses in this family known to cause disease in humans (human herpes viruses (hhv)), include:


virus type
diseases
hhv-1 (hsv-1) herpes labialis.
hhv-2 (hsv-2) herpes genitalis.
hhv-3 (vzv) chickenpox and herpes zoster (hz).

hhv-4 (ebv) infectious mononucleosis.

hhv-5 (cmv) infectious mononucleosis-like syndrome.
hhv-6 roseola infantum.

hhv-7 pityriasis rosea.
hhv-8 kaposi s sarcoma.


herpes simplex virus (hsv):

it has been separated into two types:
type 1: are usually orofacial (herpes labialis).
type 2: are usually genital (herpes genitalis).
the virus usually spread by direct contact.
herpes viruses are not curable, after the episode of the primary infection, the virus may become latent, possibly within nerve ganglia, but still capable of giving rise to recurrent bouts of vesication (recurrences or recrudescences).

presentation:
1- primary infection:
a- herpes labialis: the most common recognizable manifestation in children is an acute gingivostomatitis, accompanied by malaise, headache, fever and cervical lymphoadenopathy. vesicles, soon turning into small ulcers, can be seen scattered over the lips and mucous membranes. the illness lasts about 2 weeks.
b- herpes genitalis: usually transmitted sexually, cause multiple and painful genital or perianal vesicles which rapidly ulcerate.
c- herpetic whitlow: result from direct inoculation of the virus into the skin causing a pus-filled blisters on a fingertip, mostly seen in medical personnel and children.
2- recurrent (recrudescent) infections:
a- herpes labialis: usually on the lips and the vermilion border (can occur anywhere on face).
b- herpes genitalis: usually on the genitalia, but can occur anywhere.
? the lesions usually recur at the same place.

triggering factors:
a- herpes labialis: fever, upper respiratory tract infections (cold sores), ultraviolet radiation, menstruation, or even stress.
b- herpes genitalis: physical stress, emotional stress, steroids, menstruation, imunossupression, and friction from sexual activity or tight clothes
clinical features: tingling, burning or even pain is followed within a few hours by the development of erythema and clusters of tense vesicles (grouping arrangement). crustation occurs within 24–48 h and the whole episode lasts about 2 weeks.
? vesicles differ from those in primary infections by: (1) their smaller size. (2) fewer number. (3) closer grouping. (4) the usual absence of constitutional symptoms or lymphadenopathy, unless there is secondary bacterial infection.


diagnosis of hsv:
1- tzanck smear: show the multinucleated giant cells.
2- serological tests: by complement fixation test, especially in the primary infections.
3- culture: of the virus from vesicular fluid.
complications:
1- herpes encephalitis or meningitis.
2- disseminated herpes simplex.
3- eczema herpeticum: widespread infections, usually occur in atopic dermatitis.
4- secondary bacterial infection.
5- recurrent dendritic ulcers leading to corneal scarring.
6- erythema multiforme.
treatment:
1- mild uncomplicated infections: require no treatment only prevention of secondary bacterial infection by topical antiseptic agent.
2- sever, widespread, or systemic infections: acyclovir tablets, 200 mg five times daily or 400 three times daily for 7 days.
3- recurrent infections:
a- episodic treatment: if less than 6 recurrences per year.
started at the first signs of a recurrence and taken for a few days. topical acyclovir cream (applied five times daily), decrease the length of attacks and increases the intervals between them.
b- suppressive therapy: if more than 6 recurrences per year.
involves taking an antiviral drug (acyclovir tablets 400mg twice daily) for prolonged periods (6 months).
varicella-zoster virus (vzv):
causing chickenpox and hz.

varicella (chickenpox):
it is the primary infection of vzv, it is a highly contagious viral infections, transmission occur via airborne dropinglets or contact with the vesicular fluid. patients are contagious 2 days before and 5 days after onset of rash. the ip averages 2 weeks.
presentation and course:
prodromal symptoms (fever, chills, malaise, headache, and anorexia) are followed by the development of papules, which turn rapidly into clear vesicles, which may become pustules, over the next few days the lesions crust and then clear, sometimes leaving depressed scars. lesions appear in crops, so lesions of different stages are present at the same time. the lesions are often itchy, and are most profuse on the trunk (centripetal). the vesicles may also develop in the mucous membranes (especialy of the mouth).
fever usually persists as long as new lesions continue to appear, and its height is generally proportional to the severity of the rash. prolonged or recurrent high fever may indicate a secondary bacterial infection or another complication.
an attack of chickenpox usually confers lifelong immunity.
complications
1- secondary bacterial infection.
2- primary varicella pneumonia (mostly in adult patients).
3- bacterial pneumonia, otitis media, and suppurative meningitis.
4- haemorrhagic or lethal chickenpox in the immunocompromised.
5- scarring.
treatment:
1- symptomatic relief : antipruritic lotions (e.g. calamine), antipyretics (except aspirin), and antihistamines.
2- antibiotics: indicated for secondary bacterial infections.
3- systemic antiviral (acyclovir 20 mg /kg, 5 times daily for 7 days), indicated for:
a- severe attacks.
b- immunocompromised.
c- patients 13 years of age or older (more sever & more complicated disease).
? varicella vaccine (varivax, varilrix) is a live (attenuated) virus administered to protect against chickenpox. it was recommended in 2006 as a part of the routine immunization schedule in the us, not all countries provide the vaccine due to its cost.

herpes zoster (hz) (shingles):
hz is caused by vzv. an attack is a result of the reactivation of virus that has remained dormant in a sensory root ganglion since an earlier episode of chickenpox.
the incidence of shingles is highest in old age, and in some conditions such as hodgkin’s disease, aids, and leukemia, which weaken normal defense mechanisms.
? patients with zoster can transmit the virus to others in whom it may cause chickenpox (if there is no previous attack).
presentation and course:
attacks usually start with a burning pain, soon followed by erythema and grouped vesicles (grouping arrangement), scattered over a dermatome (dermatomal distribution) commonly the thoracic segments or the ophthalmic division of the trigeminal nerve. it may affect more than one adjacent dermatome.
the clear vesicles quickly become purulent, and over a few days burst and crust. hemorrhagic or necrotic lesions may indicate an underlying immunodeficiency state.
? hz is characteristically unilateral, and usually occurs once in life.
? second episode, or bilateral infection of hz is very unusual.
? occasionally, before the rash has appeared, the initial pain is misdiagnosed as acute appendicitis, renal colic, or myocardial infarction (according to its site).


complications:
1- post herpetic neuralgia: which is a persistent neuralgic pain after the skin lesions have disappeared. it is the most common complication, its risk increase with age and severity.
2- dissimination: may occur in immunocompromised patients, devided into:
a- cutaneous (more than 20 vesicles outside the affected dermatome).
b- visceral ( lung, liver, and brain involvement).
3- motor nerve involvement, which has led to muscular paralysis.
4- secondary bacterial infection.
5- necrosis and scarring.
6- hz ophthalmicus (hz of the ophthalmic division of the trigeminal nerve): can lead to corneal ulcers and scarring.
7- ramsay-hunt’s syndrom: involvement of the geniculate ganglion, can lead to facial nerve paralysis and auditory symptoms.
treatment:
1- systemic antiviral therapy: acyclovir 800 mg five times daily for 7 days, should be given in the early stages of the disease (within the first 3 days). famciclovir and valaciclovir are as effective as acyclovir.
indications: (a) old patient (more than 50 years). (b) very painful or sever case. (c) immunosuppressed patient. (d) dissimination. (e) motor nerve involvement. (f) hz ophthalmicus. (g) ramsay-hunt’s syndrom.
2- supportive therapy: with rest, analgesics and antipruritic lotions as calamine.
3- antibiotic therapy: for secondary bacterial infection.
4- treatment of post-herpetic neuralgia: gabapentin, carbamazepine, amitriptyline, or topical capsaicin cream.
5- topical antiviral agents is not effective in hz .
? acyclovir: is an antiviral drug that acts as a specific inhibitor of herpesvirus dna polymerase. famciclovir and valaciclovir are metabolized by the body into acyclovir and are as effective as acyclovir, with fewer doses per day.
human papilloma virus (hpv)
hpv is a dna virus, with more than 100 recognizable serotypes.
hpv infect the skin causing warts, which transmitted by direct contact.
types of warts:
many types of wart have been identified, varying in shape and site affected, as well as the serotype of human papillomavirus, these include:
1- common wart (verruca vulgaris): a raised wart with rough surface, most common on hands, but can occur anywhere on the skin and even on the mucous membrane (especially oral), caused by hpv 1,2, and 4.
2- flat wart (verruca plana): a small, smooth, flattened, skin-coloured or light brown. lesions are multiple, painless and mostly on a face of children. caused by hpv 3, and 10.
like common warts, are sometimes arranged along a scratch line (koebner phenomenon).
3- genital wart (condyloma acuminata): papillomatous cauliflower-like lesions, with a moist macerated surface on the genitalia. usually transmitted by sexual contact or may be caused by autoinoculation from common warts elsewhere, caused by hpv 6,11,16 and 18.
4- filiform or digitate wart: a thread- or finger-like wart, most common on the face. these are most common in the beard area of adult males and are spread by shaving.
5- plantar wart: these have a rough surface, which protrudes slightly from the skin.
6- periungual wart: warts that occurs around the nails.
7- mosaic wart: a group of tightly clustered warts, commonly on the soles.
course:
? warts commonly occur in children and young adults, but they may appear at any age.
? their course is highly variable most resolve spontaneously in months, and others may last years or a lifetime. such spontaneous resolution, sometimes heralded by a punctate blackening (black dots) caused by capillary thrombosis.
? mosaic warts are slow to resolve and often resist all treatments.
? warts persist and spread in immunocompromised patients (especially with lymphoreticular disease).
complications:
1- pain: some plantar warts are very painful.
2- secondary bacterial infection.
3- malignant change: generally it is rare, but may occur in the following conditions:
a- certain genital strains (16&18), predispose to cervical or penile carcinoma (scc).
b- hpv infections in immunocompromised patients (e.g. renal transplantation), especially on light-exposed areas.
c- epidermodysplasia verruciformis: a rare inherited disorder, in which there is a impairment of cell-mediated immunity with universal wart infection.
differential diagnosis:
1- molluscum contagiosum: smooth, dome-shaped, with central umbilication.
2- plantar corn: it is usually on a pressure site, single, painful, no black dots, with preservation of overlying skin lines, and on paring have central keratotic core.
while plantar warts, are usually at any site, multiple, painless, may have black dots, with no preservation of overlying skin lines, and on paring have bleeding points of their capillary loops.
3- condyloma lata: the lesions are flatter, greyer and less well defined than condyloma acuminata, with other signs of secondary syphilis and positive serological tests.

treatment of warts:
1-topical: caustic material (salicylic acid, lactic acid, or tca), imiquimode, podophylline, or 5-flourouracil.
2- intralesional: 2% zinc sulphate, bleomycin, or interferon alfa.
3- physical: excision, curettage &/or electrodesication, cryotherapy, or co2 laser.
4- systemic: oral zinc sulphate, cimetidine, etretinate, interferon, or bcg vaccination.
5- others, include:
a- antiviral therapy: recently cidofovir (vestide) treatment is promising, it can be used systemically(iv) or topically, or by intralesional injection, it is very expensive.
b- psychological methods: many myths and some studies claiming that warts can be effectively treated by suggestion.
c- vaccination: prophylactic vaccination to prevent (not treat) genital wart. two types available: (1) cervarix, prevent hpv 16&18. (2) gardasil, prevent hpv 6,11,16&18.

poxvirus

the poxviruses are double-stranded dna viruses. they are the largest animal viruses and can be seen with light microscopy. it have 3 main genuses: orthopox causing smallpox which is eradicated since 1978, molluscipox causing mc, and parapox causing orf.

molluscum contagiosum (mc):
presentation and course:
the incubation period ranges from 2 to 6 weeks. individual lesions are shiny, pearly or pink in color, smooth surface, firm, dome shaped papule, averaging 3-5 mm. a central punctum, which may contain a cheesy core, gives the lesions their characteristic umbilicated look. the most commonly involved sites are the face in children and the genital areas in adults.
multiple lesions are common, and often several members of one family are affected. they may spread by autoinoculation, scratching (koebner phenomenon), or touching a contaminated fomites. untreated lesions usually clear in 6–9 months.
treatment
? generally: conservative non scarring methods should be used for children, and genital lesions in adults should be definitively treated to prevent spread by sexual contact.
? treatment options: curettage, cauterization, cryosurgery, cantharidin, imiquimod, tretinoin, chemical solutions (phenol, lactic acid, tca, or koh), or co2 laser.
?the antiviral agent cidofovir has recently been shown to effectively resolve molluscum lesions (used either intravenously or topically).

orf
presentation and course:
the incubation period is 5–6 days. lesions, which may be single or multiple, start as small firm papules that change into pustular nodules with a violaceous or erythematous surround. it can be transmitted to those handling infected animals (especially the animal s head). the condition clears up spontaneously in about a month.
treatment: a topical antibiotic helps to prevent secondary infection otherwise no active therapy is needed.
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