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VIRAL INFECTIONS. CHICKEN POX. The varicella zoster virus (VZV) is the cause of both varicella (chickenpox) and zoster (shingles). Zoster is the result of reactivation of this residual latent virus. The virus is transmitted by droplet infection from the nasopharynx.
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CHICKEN POX • The varicella zoster virus (VZV) is the cause of both varicella (chickenpox) and zoster (shingles). • Zoster is the result of reactivation of this residual latent virus. • The virus is transmitted by droplet infection from the nasopharynx. • Patients are infectious to others from about 2 days before to 5 days after the onset of the rash • Vesicle fluid contains a large amount of virus. Completely dry scabs are not infectious.
Varicella confers lasting immunity and second attacks are uncommon, especially in immunologically healthy subjects. • Cell-mediated immunity (CMI) is more important in both protection against and control of the infection. If the primary infection occurs when CMI is impaired, as in organ-transplant patients,varicella may be severe and occasionally fatal. • Maternal varicella in the first 20 weeks of pregnancy is associated with an approximate 2% risk of fetal damage.
FVS including skin lesions, central nervous system and ocular defects, and limb hypoplasia with a 30% mortality within the first year of life. • Maternal zoster in pregnancy is not associated with intrauterine infection. • If the mother has varicella within 4 days before to 2 days after term, the neonate would have no maternal antibody and is at risk of severe varicella a mortality rate up to 30% in the absence of treatment.
Their distribution is centripetal, and on the limbs the eruption is more profuse on thighs and upper arms than on lower legs and forearms. • Constitutional symptoms tend to be proportionate to the fever. In some patients pruritus is troublesome. After about 4 days, no new crops of lesions appear and existing vesicles dry and crust. • Complications. These are rare in otherwise healthy children, are less infrequent in neonates and adults and are common in the immunosuppressed. • Encephalitis ,pneumonia ,hepatitis ,secondary infection, Reye’s syndrom,…
Zoster • The first manifestation of zoster is usually pain, which may be severe, and may be accompanied by fever, headache, malaise and tenderness localized to areas of one or more dorsal roots. • Closely grouped red papules, rapidly becoming vesicular and then pustular, develop in a continuous or interrupted band in the area of one, occasionally two and, rarely, more contiguous dermatomes. • In uncomplicated cases recovery is complete in 2-3 weeks in children and young adults, and 3-4 weeks in older patients. • The thoracic (53%), cervical (usually C 2,3,4, 20%), trigeminal, including ophthalmic (15%) and lumbosacral (11%) .
Trigeminal nerve zoster. In ophthalmic nerve zoster the eye is affected in two-thirds of cases, especially when vesicles on the side of the nose indicate involvement of the nasociliary nerve. • Pressure on the facial nerve motor fibres adds facial palsy, which with the ear pain and associated vesicles completes the classical triad of the Ramsay-Hunt syndrome; • The commonest and most intractable sequel of zoster is post-herpetic neuralgia, as persistence or recurrence of pain more than a month after the onset of zoster, but better considered after 3 months. It is unusual in childhood and increases in incidence and severity with age.
Treatment • Varicella in the otherwise healthy child requires only symptomatic treatment. 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. • An antiviral is indicated for varicella in adults and for severe varicella or zoster infections at any age in the immunocompromised. typically 10 mg/kg or 500 mg/m2 8-hourly intravenously or 4 g per day orally . Courses of 5, 7 and 10 days have been used and some advocate a change from intravenous to oral drug after 48 hours. In general practice, zoster is often treated with aciclovir 800 mg five times a day for 7-10 days.
In the treatment of herpes zoster oticus (Ramsay-Hunt syndrome), steroid therapy is better established, probably because of the central importance of inflammatory swelling in its pathogenesis. A combination of aciclovir plus prednisolone may give best results. • For post-herpetic neuralgia: A tricyclic antidepressant such as amitriptyline or nor triptylene , sodium valproate (or other anticonvulsant, e.g. clonazepam or carbamazepine), Gabapentine, Topical capsaicin 0.025%.
Modes of transmission • Warts are spread by direct or indirect contact. For infection to occur, the wart virus particle may need to come into contact with a stem cell in the basal epidermal layer. Thus, impairment of the epithelial barrier function, by trauma (including mild abrasions), maceration or both, greatly predisposes to inoculation of virus, and is generally assumed to be required for infection at least in fully keratinized skin. • Iatrogenic transmission. • both sexual and non-sexual routes are significant in transmission of childhood anogenital warts
Common warts are most commonly situated on the backs of the hands and fingers. New warts may form at sites of trauma, though this Koebner-like isomorphic phenomenon is usually less marked than in plane warts. About 65% of warts disappear spontaneously within 2 years.
Periungual warts. Common warts around the nails, specially at nail folds or beneath the nail, can disturb nail growth.Nail biting may increase the risk of infection at this site.
plantar warts . Most are beneath pressure points, the heel or the metatarsal heads. Individuals may be affected by single or numerous lesions. small bleeding points, the tips of the elongated dermal papillae, are evident.
Plane warts (flat warts).they are round or polygonal in shape • The face and the backs of the hands and the shins are the sites of predilection.
Anogenital warts(condyloma acuminatum ) are common and are caused in 75% by HPV -6. The remainder are caused by HPV-11 or more unusual, low-risk HPVs.
Treatment • Salicylic acid. The keratolytic effect of salicylic acid helps to reduce the thickness of warts and may stimulate an inflammatory response. A preparation containing 12-26% salicylic acid, possibly with additional lactic acid, in a quick-drying collodion or acrylate base, is the treatment of first choice for common and plantar warts. • Podophyllin and podophyllotoxin. contraindication in pregnancy • Surgery. Excision is usually to be avoided since scarring is inevitable and recurrences of the wart in the scar are frequent.
Cryotherapy. Carbon dioxide snow and liquid nitrogen can both produce cold thermal damage to the skin. Liquid N2 is commonly used in hospital practice, applied either by a cotton wool bud or from a cryospray. The main disadvantage of freezing is pain. • laser. The carbon dioxide laser has been used to treat a variety of different forms of wart, both cutaneous and mucosa. • Others. Cimetidine ,zinc ,retinoids,…
Herpes simplex • There are two major antigenic types: type I, which is classically associated with facial infections; and type 2, which is typically genital, although there is considerable overlap in disease manifestations. • Both type 1 and type 2 HSV are acquired by direct contact with, or droplets from, infected secretions entering via skin or mucous membrane. • Primary type 1 infections occur mainly in infants and young children, when they are usually minimal and often subclinical. • Type 2 infections occur mainly after puberty, and are often transmitted sexually. The primary HSV-2 infection is more commonly symptomatic.
Herpetic gingivostomatitis . This is the most common clinical manifestation of primary infection by type 1. fever, which may be high, malaise, restlessness and excessive dribbling. Drinking and eating are very painful and the breath is foul-smelling. The gums are swollen, inflamed and bleed easily. • Recurrent infection.Itching or burning precedes by an hour or two the development of small, closely grouped vesicles on an inflamed base. They usually become pustular and crusted before healing in 7-10 days without scarring.
TREATMENT • Mild uncomplicated eruptions of herpes simplex require no treatment. The use of a topical antiseptic agent on affected skin may help to reduce the risk of secondary bacterial infection. In severe primary infection or troublesome recurrent disease, antiviral therapy should be instigated. • Aciclovir . The usual dose is 5 mg/ kg 8-hourly intravenously , The usual oral dose is 200 mg five times daily for 5 or more days. Prophylaxis against reactivation or spread of HSV may be useful before cosmetic laser treatment of the face, as widespread herpes has been reported following such procedures.
With the eradication of smallpox, molluscum contagiosum (Mc)became the only remaining poxvirus infection to specifically afflict humans. This disorder is caused by the MC virus (MCV), a member of the Molluscipox genus of Poxviridae. MC is a common, benign, selflimited process in children. It also occurs in adults, usually as a sexually transmitted disease, and more recently has been observed with increasing frequency in immunocompromised hosts.
Transmission is via skin-to-skin contact and, less commonly,fomites. MC lesions are firm, umbilicated pearly papules with a waxy surface. They may occur anywhere on the skin surface, but are most common in skin folds and the genital region Widespread,large and occasionally deforming lesions may be seen in the setting of immunosuppression, particularly AIDS .An associated molluscum dermatitis is common, especially in children with atopic dermatitis.
DIFFERENTIAL DIAGNOSIS • The differential diagnosis of MC may include appendageal tumors, verrucae, condylomata acuminata, basal cell carcinoma, juvenile xanthogranuloma, melanocytic nevi (especially Spitz nevi), papular granuloma annulare, pyogenic granuloma or pyoderma. In immunocompromised hosts, infectious processes such as cryptococcosis or histoplasmosis may mimic Mc.
TREATMENT • Most papules of MC resolve spontaneously, but treatment may be requested when there are numerous or cosmetically significant lesions. There are many treatment options, including curettage, manual expression, liquid nitrogen, chemovesicants, topical keratolytics, topical cidofovir, tape stripping and laser .
