VIRAL INFECTIONS OF THE SKIN

Herpes Simplex Virus

• HSV-1
• HSV-2

Herpes Simplex Virus type-1(HSV-1)

• Remains latent in trigeminal root ganglion.
• HSV-1, is classically associated with facial infections- Gingivostomatitis and recurrent cold sores ( skin or lip)
• Keratoconjuntivitis generally with lid swelling and vesicles, dendritic ulcers may be seen, (untreated repeated attacks may lead to visual impairment).
• Meningoencephalitis (characterised by fever, headache and confusion).

HSV-1 causes cold sores on the mouth or lips.

HSV-1 infection

Orolabial HSV-1 infection

Diagnosis

• PCR on CSF
• RBC on CSF

Herpes Simplex Virus type-II (HSV-II)

• Latent in sacral nerve ganglia.
• Causes herpes genital infections: Painful vesicular lesions of genitals and anal area.
• In neonates it may have one of these three presentations:
• Disseminated with liver involvement.
• Encephalitis
• Skin, eyes or mouth

HSV-2 infection

Diagnosis

• PCR on CSF ( for encephalitis)
• Viral culture with fluorescent antibody stain to identify virus.

Treatment

• Primary HSV

Famciclovir- 250 mg XTID

Valaciclovir- 500 mgX BID

Aciclovir- 200mg, 5 times a day

i.v Aciclovir- 5mg/Kg X TID (if severe and preventing oral intake

• Recurrent HSV- 1 or 2

Aciclovir ointment 3-5 times/day

Oral aciclovir 200mg 6hrly

Famciclovir 250mgXBID

Valaciclovir 500mg daily

In immunocompromised (aciclovir 400mgXQID, famciclovir 500mgXBID, valaciclovir 1gXBID)

• Severe complications

i.v. aciclovir 10mg/kgX TID (upto 20mg/kg in severe encephalitis)

• Disease suppression

Aciclovir 400mgXBID

Famciclovir 250mgXBID

Valaciclovir 500mg daily

Varicella zoster virus (VZV)

• The varicella zoster virus (VZV) is the cause of both varicella (chickenpox) and zoster(shingles).
• The primary infection of varicella includes viraemia and a widespread eruption, after which the virus persists in dorsal root ganglion, usually sensory. Zoster is the result of reactivation of this residual latent virus.

Chickenpox

• Humans are the only known reservoir of VZV.
• Chickenpox is highly contagious.
• VZV is dermo and neurotropic.
• Spread by the aerosol route.

Clinical features

• Clinically, chickenpox presents with a rash, low-grade fever, and malaise, although a few patients develop a prodrome 1–2 days before onset of the exanthem.
• Disease is well tolerated in children.
• It is more severe in adults, pregnant women and immunicompromosed.
• Incubation period is 14-21 days, after which vesicular eruption begins( first on the mucosal surfaces followed by rapid dissemination in a centripetal distrubition.
• New lesions occur every 2-4 days associated with fever.
• The rash progresses from small pink macules to vesicles and pustules within 24hrs, followed by crusting.
• Self-limiting cerebellar ataxia (rarely).
• Maternal infection in early pregnancy carries a risk of neonatal damage, and disease within 5 days of delivery can lead to severe neonatal varicella.

Diagnosis

• Dx is usually clinically obvious.
• For confirmation of Dx: Aspiration of vesicular fluid and PCR or tissue culture.

Treatment

• Varicella in the otherwise healthy child requires only symptomatic treatment. 
• In some instances aciclovir is used in childhood chickenpox to reduce the severity and duration of the eruption.
• Rest and analgesics are sufficient for mild attacks of zoster in the young. Soothing antiseptic applications may be helpful and secondary bacterial infection will require antibiotics.
• Aciclovir, valaciclovir and famciclovir are required in the management of the immunocompromised or any case of pneumonitis.

Shingles

Herpes zoster (shingles) is a sporadic disease that results from reactivation of latent VZV from dorsal root ganglia.

Commonly seen in elderly.

Clinical features

• Herpes zoster is characterized by a unilateral vesicular dermatomal eruption, often associated with severe pain. The dermatomes from T3 to L3 are most frequently involved. 
• In children, reactivation is usually benign; in adults, it can be debilitating because of pain.
• The onset of disease is heralded by pain within the dermatome, which may precede lesions by 48–72 h; an erythematous maculopapular rash evolves rapidly into vesicular lesions.
• When branches of the trigeminal nerve are involved, lesions may appear on the face, in the mouth, in the eye, or on the tongue. Zoster ophthalmicus is usually a debilitating condition that can result in blindness in the absence of antiviral therapy.
• In the Ramsay Hunt syndrome, pain and vesicles appear in the external auditory canal, and patients lose their sense of taste in the anterior two-thirds of the tongue while developing ipsilateral facial palsy. The geniculate ganglion of the sensory branch of the facial nerve is involved.
• CNS involvement may follow localized herpes zoster: myelitis or encephalitis.

Treatment

• In severe infection and in the immunocompromised:

Early therapy with aciclovir 800mgX 5times daily or valaciclovir1g X TID, or i.v aciclovir 10mg/kg X TID

Reduce early and late onset pain esp. in pt. >65yrs.

• Post-herpetic neuralgia:

Aggressive analgesia and the use of transcutaneous nerve stimulation.

Plus amitriptyline 25-100mg daily or gabapentin 300mg daily increasing slowly to 300mg BID or more.

Human Papillomavirus Infections

Human papillomaviruses (HPVs) selectively infect the epithelium of skin and mucous membranes. These infections may be asymptomatic, produce warts, or be associated with a variety of both benign and malignant neoplasias.

Clinical Manifestations

• The clinical manifestations of HPV infection depend on the location of lesions and the type of virus.
• Common warts usually occur on the hands as flesh-colored to brown, exophytic, and hyperkeratotic papules. 
• Plantar warts may be quite painful; they can be differentiated from calluses by paring of the surface to reveal thrombosed capillaries.
•  Flat warts (verruca plana) are most common among children and occur on the face, neck, chest, and flexor surfaces of the forearms and legs.
• Anogenital warts develop on the skin and mucosal surfaces of external genitalia and perianal areas .
• Among circumcised men, warts are most commonly found on the penile shaft. Lesions frequently occur at the urethral meatus and may extend proximally.
• Mosaic warts: mosiac like plaques of tightly packed individual warts.

Common wart

Plantar wart

Flat warts (verruca plana)

Anogenital warts

Mosaic warts

Treatment

• Majority of cases of viral warts resolve spontaneously.
• Initial t/t:
• Salicylic acid or salicylic and lactic acid combination along with regular and frequent paring of the hyperkeratotic skin.
• Cryotherapy using liquid nitrogen: As an alt. or in case of failure of above t/t.
• Warts close to/under the nails: Cutting of nails and electrodesiccation or destructive therapy.
• Other t/t:
• Systemic retinoids, intralesional injections of bleomycin or interferon, application of diphencyprone or dinitrichlorobenzene, imiquimod.

Molluscum contagiosum

• Molluscum contagiosum virus is an obligate human pathogen that causes distinctive proliferative skin lesions. These lesions measure 2–5 mm in diameter and are pearly, flesh-colored, and umbilicated, with a characteristic dimple at the center. A relative lack of inflammation and necrosis distinguishes these proliferative lesions from other poxvirus lesions. Lesions may be found—singly or in clusters—anywhere on the body except on the palms and soles and may be associated with an eczematous rash.
• Molluscum contagiosum is highly prevalent in children and is the most common human disease resulting from poxvirus infection
• Molluscum contagiosum can be associated with immunosuppression and is frequently seen among HIV-infected patients

Diagnosis

The diagnosis of molluscum contagiosum is typically based on its clinical presentation and can be confirmed by histologic demonstration of the cytoplasmic eosinophilic inclusions (molluscum bodies) that are characteristic of poxvirus replication.

Treatment


There is no specific systemic treatment for molluscum contagiosum, but a variety of techniques for physical ablation have been used. Cidofovir displays in vitro activity against many poxviruses, and case reports suggest that parenteral or topical cidofovir may have some efficacy in the treatment of recalcitrant molluscum contagiosum in immunosuppressed hosts.