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More common skin infections in children
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     1 Department of Dermatology, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, LE1 5WW

    Correspondence to: m.sladden@doctors.org.uk

    Childhood skin infections are commonly seen in both primary care and dermatology practice worldwide. They consume considerable resources and need careful management. However, education and reassurance of patients and parents, combined with simple treatment and self management, play a vital part in successful treatment. We recently reviewed four common childhood skin infections: molluscum contagiosum, cutaneous viral warts, impetigo, and tinea capitis.1 We now review four more skin infections commonly seen in children, describing the epidemiology, clinical features, and treatment of each. For conditions with limited evidence, we provide pragmatic advice and recommendations.

    Sources and selection criteria

    We searched Medline, Embase, and the Cochrane Library by using the terms "scabies," "head lice," "folliculitis," and "herpes simplex virus." We included randomised trials, reviews, meta-analyses, and guidelines.

    Scabies

    Scabies is an intensely itchy dermatosis caused by the mite Sarcoptes scabiei. The infestation can occur at all ages but particularly occurs in children. It is a common public health problem in poor communities and developing countries.

    Scabies is highly contagious and is spread from person to person by direct skin contact. Transfer from clothes and bedding occurs rarely and only if contaminated by infectious people immediately beforehand.2 Infestation occurs when pregnant female mites burrow into the skin and lay eggs. After two or three days the larvae emerge and dig new burrows. They mature, mate, and repeat this cycle every two weeks.

    The main symptoms of scabies are caused by the host immune reaction to burrowed mites and their products.3 Symptoms appear within two to six weeks of the initial infestation, but reinfestation can provoke symptoms within 48 hours. The most common presenting lesions are papules, vesicles, pustules, and nodules. The pathognomonic sign is the burrow—a short, wavy, grey line that is often missed if the skin is eczematised, excoriated, or impetiginised. In adults, scabies is characterised by intractable pruritus, which is worse at night, and lesions in the web spaces, fingers, flexor surfaces of the wrists, axillae, and genital areas.

    In infants and young children, scabies often affects the face, head, neck, scalp, palms, and soles (fig 1). Widespread eczematised erythema is common, particularly on the trunk, and is sometimes more troublesome than are lesions at typical sites. Very young babies do not scratch and may just seem miserable or feed poorly. Pinkish brown scabetic nodules are common in babies and can resemble mastocytomas or other infiltrative conditions.

    Fig 1 Typical childhood scabies, showing multiple pruritic papules, vesicles, and pustules. The pathognomonic scabetic burrows are arrowed

    Summary points

    A high index of suspicion is needed to diagnose scabies correctly

    Permethrin 5% dermal cream is the treatment of choice for scabies in the UK, Australia, and USA; however, incorrect or inappropriate treatment is ineffective and promotes drug resistance

    The diagnosis of active head lice infestation, as shown by the existence of live lice, is essential before starting treatment

    Pediculosis capitis should be treated with aqueous lotions or liquid formulations, two applications seven days apart; we use permethrin 5% dermal cream (off-licence indication) or malathion

    Folliculitis is common, is usually caused by Staphylococcus aureus, and is effectively treated by topical antiseptics and topical antibiotics

    In severe or refractory folliculitis, nasal swabs from the patient and immediate relatives should be taken to identify asymptomatic carriers of S aureus

    Herpes simplex virus can result in eczema herpeticum in patients with pre-existing (often mild) atopic eczema

    A high index of suspicion is needed to make the correct diagnosis of scabies because of the wide range of symptoms and presentations,. For example, the distribution of lesions in adults (rarely on the face and neck) and children (commonly on the face and neck) is different. A history of itching in several family members over the same period is virtually pathognomonic of scabies. Lack of a history of itching in family members does not exclude scabies, however, because family members may not admit to a history of possible scabies, and some people with scabies genuinely do not itch. Untreated, scabies can continue for many months. Recurrence of symptoms after treatment does not exclude scabies.

    The definitive diagnosis of scabies relies on microscopic identification of mites, eggs, or faecal pellets from burrow scrapings. Treatment should be given if scabies is suspected, even without microscopic evidence.4 A variety of effective topical medications are available to treat scabies, including permethrin, malathion, benzyl benzoate, lindane, and crotamiton. Treatment selection is determined by factors such as the age of the child (see www.bnf.org),5 local experience of and resistance patterns to scabeticides, drug toxicity, and (particularly in underdeveloped countries) cost and availability. Children should be given aqueous preparations, as alcoholic lotions sting and can make them wheeze. Topical preparations must be applied correctly to maximise the success of treatment (box).

    Permethrin 5% dermal cream is the treatment of choice for scabies in the United Kingdom, Australia, and the United States.3 It is the most effective topical agent,2 is well tolerated, and has low toxicity (www.bnf.org). It should be applied on two occasions, one week apart. For children under 2 years, medical supervision is needed.

    Malathion is the second choice for treatment. Medical supervision is needed for children under 6 months. Malathion is cheaper than permethrin and, for adult contacts, cheaper than a prescription.

    Lindane is less effective than permethrin and has been withdrawn in many countries because of reports of aplastic anaemia and concerns about potential neurotoxicity. Benzyl benzoate is irritant and not recommended for children.

    The oral antiparasitic drug ivermectin is an effective scabicide.2 Two doses of ivermectin (200 μg/kg body weight, two weeks apart) seem to be as effective as a single application of permethrin.6 However, the drug has not been evaluated in children weighing less than 15 kg, and its role in treating scabies remains unclear.7

    Important considerations when treating children with scabies

    Aspects of treatment

    Treatment should be applied to the whole body (except head and neck), including the web spaces of fingers and toes, the genitalia, and under the nails

    In children aged up to 2 years, the application should be extended to the scalp, neck, face, and ears

    All members of the affected household should be treated at the same time (as should the sexual contacts of adults)

    The application should be washed off after the recommended time (12 hours for permethrin) and clothes and bed linen machine washed at temperatures above 50°C4

    Permethrin and malathion should be applied twice, one week apart

    Treatment must be reapplied to the hands if they are washed

    The itch and eczema of scabies may continue for some weeks after successful treatment; moisturisers, crotamiton, and moderate strength topical corticosteroids reduce these symptoms. However, persistent symptoms suggest that scabies eradication was unsuccessful (www.bnf.org)

    Common reasons for treatment failure

    Children suck the treatment off their fingers

    People wash the lotion off their hands (and do not reapply it)

    Pregnant women, people with other skin diseases, and babies often escape treatment

    Children sometimes live in more than one household

    The treatment may not have been applied on two occasions, seven days apart

    Head lice (pediculosis capitis)

    Pediculosis capitis is a scalp infestation by the human head louse (Pediculus humanus capitis) (fig 2). Head lice infestation is common throughout the world, crossing all economic and social boundaries.8 It is most common in children aged 4-11 years, but occurs in people of all ages.9 In Western societies, parents are often embarrassed if children have head lice, because of the misconception that lice are associated with poor hygiene. In other societies, the infestation is considered normal. The worldwide cost of treatment is high.10

    Fig 2 Pediculosis capitis, showing live lice and nits

    The head louse is a grey-brown, six legged wingless insect, 1-3 mm long, which feeds by sucking blood from the host's scalp. Once infestation occurs, the female louse mates and lays eggs within two days of becoming an adult. The eggs (nits) are deposited on a hair, attached close to the scalp by a glue-like glandular secretion. They hatch in seven days, and the eggshells are left empty. Young lice (nymphs) take 10-14 days to become adults, when they too begin laying eggs. The infestation spreads from person to person only by relatively prolonged head to head contact, usually occurring between people who know each other well.11 Head lice found on hats, pillows, and other locations are usually dead or sick and unlikely to transmit the infestation.9 Most people are initially asymptomatic and unaware of the infestation,12 because pruritus, an allergic reaction to louse saliva, takes up to three months to develop.13 Head lice infestation is a common cause of scalp impetigo in developed countries,14 but is not a vector for other diseases.

    A diagnosis of active infestation is confirmed by the existence of live lice.15 The presence of eggs alone (without live lice) may reflect previous or treated infestation. Treatment should not be applied unless live lice are discovered,16 in order to minimise the development of drug resistance. Automatic treatment of family members is not necessary, but contacts should have detection combing for live lice and be treated if positive.5

    There is good evidence that permethrin,17 18 synergised pyrethrin (natural pyrethrin combined with other agents to enhance activity),18 and malathion19 20 are effective at treating pediculosis capitis.9 However, as resistance to insecticides is increasing,21 treatment should be based on local experience and resistance patterns.

    Head lice infestation should be treated with lotion or liquid formulations. Shampoos are diluted too much in use to be effective. We advise the use of aqueous solutions (not alcohol based preparations) to avoid skin irritation and wheeze. At least 50 ml (100 ml for thick hair) should be applied to the whole scalp and left on for 12 hours.5 Although one treatment application is usually adequate, a second application seven days after the first is recommended because some eggs may survive. Under-treatment in the presence of newly hatched young lice exacerbates drug resistance. To reduce the development of resistance, if a course of treatment fails to provide a cure (live lice present after second application), a different insecticide should be used for the next course.

    Malathion 0.5% (aqueous) liquid is rubbed into dry hair and scalp and allowed to dry naturally. It should be washed off after 12 hours and the application repeated after seven days (www.bnf.org). It is highly effective at killing both adult lice and ova. Medical supervision is needed for children under 6 months,.

    Although permethrin is active against head lice,9 the formulations and licensed methods of application of products currently available in the United Kingdom make them unsuitable for treating head lice. Our local practice is to use permethrin 5% dermal cream massaged into the scalp overnight and washed off the next morning, repeated after one week (off licence). This seems effective and overcomes problems of insecticide dilution and short contact time.

    Carbaryl 1% aqueous liquid, used similarly to malathion, is also effective at treating head lice. However, because there is a theoretical risk that it may be a human carcinogen, it is available only on prescription in the UK. For children under 6 months, medical supervision is needed.

    Mechanical measures, such as "wet combing," have been used as adjuncts to insecticides, but evidence suggests they are unhelpful.21 "Bug busting" involves meticulous combing of wet hair with the detection comb (half an hour each time) over the whole scalp every four days for a minimum of two weeks, with the aim of eradicating lice. Little evidence exists to show that "bug busting" is effective, however, and it should not be advocated as first line treatment in the general population.9 20 Electronic combs and tea tree oil have also been used to treat head lice, but evidence of effectiveness is lacking. In developing countries, where products are usually unavailable or prohibitively expensive, patients may choose cheaper or traditional treatments (for which there is little evidence) or low grade agricultural insecticides (which can be fatal).22

    Persistent head lice is a common and frustrating problem. It is important to explain to parents the difference between resistance and reinfection. Parents should liaise with the school if their children have head lice.

    Folliculitis

    Folliculitis is a superficial inflammation of the hair follicles. It is common and can occur at any age.23 It is usually caused by bacteria, particularly Staphylococcus aureus, but can also be caused by Pityrosporum. Persistent bacterial folliculitis can be caused by diabetes, friction from tight jeans, occlusive dressings, and shaving.

    Folliculitis begins as inflammation of the follicular ostium and can be pruritic or painful. The lesions develop into 1-5 mm yellow-grey papules or pustules, with surrounding erythema, confined to the follicular ostia (fig 3). They can be grouped or discrete and usually occur on the scalp, face, buttocks, and extremities. There are usually no systemic symptoms.

    Fig 3 Grouped yellow-grey papules and pustules of folliculitis, with surrounding erythema

    Uncomplicated folliculitis is managed by removing causative factors and cleansing with topical antiseptics. Antiseptics, including chlorhexidine, triclosan, and povidone-iodine, can be used as creams or lotions, soap substitutes, and bath additives. Emollient-antiseptic combinations, such as Dermol (Dermal Laboratories) and Oilatum Plus (Stiefel Laboratories), may be particularly useful in children to reduce skin irritation.

    Fig 4 Typical targetoid lesions of erythema multiforme

    Resistant lesions respond to topical mupirocin or fusidic acid. Resistance to fusidic acid is increasing, however, and it should be used only for short periods (2 weeks).

    Fig 5 Classical eczema herpeticum, showing extensive vesicles and erosions

    For severe or refractory folliculitis, we recommend that systemic antibiotics should be used empirically, as for impetigo, depending on local bacterial resistance patterns and individual tolerability.1 Gram stain, culture, and sensitivity of lesion exudate confirm the diagnosis and guide treatment. If the infection of the follicle is deeper and involves more follicles it develops into the furuncle and carbuncle stages and usually needs incision and drainage.23 Nasal swabs should be taken from the patient and immediate relatives to identify asymptomatic carriers of S aureus.24 Nasal mupirocin is particularly effective at eliminating nasal carriage.

    Cold sores (herpes simplex virus)

    Herpes simplex virus (HSV) infection is very common and typically results in mucocutaneous disease.25 It is transmitted by mucosal or skin contact from an infected person shedding virus. HSV-1 usually causes orofacial disease, and HSV-2 causes genital infection. In this review, we focus on cold sores (herpes labialis) and exclude genital and neonatal HSV.

    Additional educational resources

    Review articles

    Walker GJA, Johnstone PW. Interventions for treating scabies. Cochrane Database Syst Rev 2000;(3): CD000320

    The management of scabies. Drug Ther Bull 2002;40: 43-6

    Dodd CS. Interventions for treating headlice. Cochrane Database Syst Rev 2001;(2): CD001165

    Johnston GA. Treatment of bullous impetigo and the staphylococcal scalded skin syndrome in infants. Expert Rev Anti Infect Ther 2004;2: 439-46

    Websites

    British Association of Dermatologists (www.bad.org.uk/doctors/guidelines)—Information and guidelines on management of common skin diseases

    Cochrane Library (www.nelh.nhs.uk/cochrane.asp)—Provides information about evidence based medicine and research methods; excellent up to date information on evidence based treatment of skin disease

    British National Formulary (www.bnf.org)—An excellent guide to prescribing topical and systemic antimicrobials in the clinical setting

    Guidelines Finder (rms.nelh.nhs.uk/guidelinesfinder)—Details of over 800 UK national guidelines; updated on a weekly basis

    Centers for Disease Control and Prevention (www.cdc.gov)—Up to date US information featuring fact sheets, frequently asked questions, and practical infection control steps

    Clinical Evidence (www.clinicalevidence.com/ceweb/conditions/skd/skd.jsp)—Summarises the current state of knowledge about the prevention and treatment of clinical conditions, on the basis of searches and appraisal of the literature

    Clinical

    Sladden MJ, Johnston GA. Common skin infections in children. BMJ 2004;329: 95-9.

    Walker GJA, Johnstone PW. Interventions for treating scabies. Cochrane Database Syst Rev 2000;(3): CD000320.

    McCarthy JS, Kemp DJ, Walton SF, Currie BJ. Scabies: more than just an irritation. Postgrad Med J 2004;80: 382-7.

    The management of scabies. Drug Ther Bull 2002;40: 43-6.

    Royal College of Paediatrics and Child Health, Neonatal and Paediatric Pharmacists Group. Medicines for children. London: Royal College of Paediatrics and Child Health Publication, 2003.

    Usha V, Gopalakrishnan Nair TV. A comparative study of oral ivermectin and topical permethrin cream in the treatment of scabies. J Am Acad Dermatol 2000;42: 236-40.

    Develoux M. Ivermectin. Ann Dermatol Venereol 2004;131: 561-70.

    Ko CJ, Elston DM. Pediculosis. J Am Acad Dermatol 2004;50: 1-12.

    Dodd CS. Interventions for treating headlice. Cochrane Database Syst Rev 2001;(2): CD001165.

    Clore ER, Longyear LA. Comprehensive pediculosis screening programmes for elementary schools. J Sch Health 1990;60: 212-4.

    Burgess IF. Treatment of head lice. Maternal and Child Health 1996;June: 142-6.

    Maunder JW. An update on head lice. Health Visit 1993;66: 317-8.

    Roberts C. Head lice. Pharm Update 1988;July/August: 240-2.

    Burgess IF. Human lice and their management. Adv Parasitol 1995;36: 271-342.

    Nash B. Treating head lice. BMJ 2003;326: 1256-7.

    Aston R, Duggal H, Simpson J, Burgess I. Head lice: a report for consultants in communicable disease control (CCDCs). Public Health Medicine Environmental Group Executive Committee, 1998. www.phmeg.org.uk (accessed 14 Jan 2005).

    Taplin D, Meinking TL, Castillero PM, Sanchez R. Permethrin 1% creme rinse for the treatment of Pediculus humanus var capitis infestation. Pediatr Dermatol 1986;3: 344-8.

    Burgess IF, Brown CM, Burgess NA. Synergized pyrethrin mousse, a new approach to head lice eradication: efficacy in field and laboratory studies. Clin Ther 1994;16: 57-64.

    Taplin D, Castillero PM, Spiegel J, Mercer S, Rivara AA, Schachner L. Malathion for treatment of Pediculus humanus var capitis infestation. JAMA 1982;247: 3103-5.

    Roberts RJ, Casey D, Morgan DA, Petrovic M. Comparison of wet combing with malathion for treatment of head lice in the UK: a pragmatic randomised controlled trial. Lancet 2000;356: 540-4.

    Meinking TL, Clineschmidt CM, Chen C, Kolber MA, Tipping RW, Furtek CI, et al. An observer-blinded study of 1% permethrin creme rinse with and without adjunctive combing in patients with head lice. J Pediatr 2002;141: 665-70.

    Wohlfahrt DJ. Fatal paraquat poisonings after skin absorption. Med J Aust 1982;1: 512-3.

    Stulberg DL, Penrod MA, Blatny RA. Common bacterial skin infections. Am Fam Physician 2002;66: 119-24.

    Johnston GA. Treatment of bullous impetigo and the staphylococcal scalded skin syndrome in infants. Expert Rev Anti Infect Ther 2004;2: 439-46.

    Whitley RJ. Herpes simplex virus infection. Semin Pediatr Infect Dis 2002;13: 6-11.

    Katz J, Livneh A, Shemer J, Danon YL, Peretz B. Herpes simplex-associated erythema multiforme (HAEM): a clinical therapeutic dilemma. Pediatr Dent 1999;21: 359-62.

    Worrall G. Clinical evidence: herpes labialis. www.clinicalevidence.com/ceweb/conditions/skd/1704/1704_I2.jsp (accessed 15 Jan 2005).

    Fawcett HA, Wansbrough-Jones MH, Clark AE, Leigh IM. Prophylactic topical acyclovir for frequent recurrent herpes simplex infection with and without erythema multiforme. BMJ 1983;287: 798-9.

    Johnston GA, Ghura HS, Carter E, Graham-Brown RA. Neonatal erythema multiforme major. Clin Exp Dermatol 2002;27: 661-4.

    Schofield JK, Tatnall FM, Leigh IM. Recurrent erythema multiforme: clinical features and treatment in a large series of patients. Br J Dermatol 1993;128: 542-5.

    Tatnall FM, Schofield JK, Leigh IM. A double-blind, placebo-controlled trial of continuous acyclovir therapy in recurrent erythema multiforme. Br J Dermatol 1995;132: 267-70.(Michael J Sladden, clinical epidemiologi)