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Managing scalp ringworm in children

Abstract

Scalp ringworm (tinea capitis) is a significant public health problem in the UK.1,2 An infection with dermatophyte fungi, it affects scalp hair follicles and surrounding scalp skin and often causes alopecia, which can be permanent. The condition is commonest in pre-adolescent children,3 although it also occurs in adolescents and adults.4 In 1995, the reported infection rate in schools in southeast London was about 2.5%,2 and there has been an increase in cases over the past few years.1 We last reviewed the management of scalp ringworm in 1996, concluding that “an 8–10 week course of oral griseofulvin (10mg/kg body weight) will normally clear the infection…”5 Since then, more data have been published on newer antifungal drugs. Here we update our advice on the treatment of children with scalp ringworm.

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  • Relevant BNFC section: 5.2

Background

Spread of scalp ringworm is due to spores or infected hairs being transferred by direct contact or by air currents onto the epidermis between hair follicles.6 In the UK, most scalp ringworm infections in children are due to Trichophyton tonsurans,1,7 which is spread from person to person (anthroponotic).5 Microsporum canis (spread from cats or dogs – i.e. animal spread [zoonotic]) used to be the commonest cause of scalp ringworm in the UK, but is now less prevalent.1 People who have no symptoms or signs of infection but from whom causative fungi can be grown are known as ‘carriers’. Scalp ringworm cases are clustered in urban areas and are more common in children of African-Caribbean origin.3

Is it scalp ringworm?

Clinical features

Using clinical diagnosis alone to identify scalp ringworm is unreliable because the presentation of the condition varies widely. The patient may have anything from noninflammatory diffuse scaling to an inflammatory disease with scaling, erythema, pustules and patchy alopecia (usually circular) or even severely inflamed, deep abscesses called kerions, which may lead to scarring and, therefore, permanent alopecia. Of note, a kerion can be mistaken for a bacterial abscess and, therefore, managed inappropriately (e.g. by surgery).8 Although some patients have itching of the scalp, others are asymptomatic. Rarely, patients have associated painful lymphadenopathy. The possibility of scalp ringworm should be considered (until ruled out by negative mycology investigations) in any child with a scaly scalp suspected to be due to dandruff or scalp eczema.9 Other conditions that may need to be ruled out include seborrhoeic dermatitis, alopecia areata, impetigo, lupus erythematosus, plaque psoriasis, pityriasis amiantacea and trichotillomania. If diagnosis is in doubt, or the GP is unable to carry out mycological investigation or is inexperienced in managing patients with scalp ringworm, the patient should be referred to a specialist.

Laboratory tests

Laboratory tests should be used wherever possible to confirm the diagnosis of scalp ringworm.6 The definitive investigation is based on mycological analysis.6 Microscopy provides the most rapid means of diagnosis (i.e. within about 24 hours) but is not always reliable. Culture results take about 2–4 weeks to become available. Usually, numerous colonies will be isolated from children with overt infection, whereas only 1–10 colonies may be isolated from carriers.

Collecting samples

Samples from the scalp should include scales and plucked hairs or hair stumps. Scales can be scraped off the scalp with a solid ‘banana’ scalpel or the blunt edge of a disposable scalpel blade.6 Plucking is not usually painful unless the lesion is very inflamed. If the hair does not come out without pulling, it is unlikely to be infected. Cut hairs are not suitable, as the infected area is usually close to the scalp surface. Samples should be sent to an appropriate laboratory in folded paper or special sample packs. If it is difficult to obtain samples in this way, a plastic sterile single-use scalp brush (or a disposable toothbrush that has its own container) can be passed repeatedly across the affected area.10

Additionally, the area can be rubbed with a moistened cotton swab, to pick up infected material that can then be cultured; this appears to be as sensitive as the toothbrush technique in isolating the responsible organism.11

Wood's light illumination

In infection due to Microsporum species, the fungal spores form a sheath on the outside of the hair, and fluoresce bright green if illuminated using ultraviolet (Wood’s) light.9 However, this test does not identify infection with Trichophyton species, in which the spores collect only inside the hair shaft, such that there is no fluorescence.9 So, as T. tonsurans is now the commonest cause of scalp ringworm in the UK, the test is no longer reliable in the diagnosis of the infection.

What about screening?

If the source of scalp ringworm infection is human, close contacts (e.g. family, friends) of the patient should be examined clinically for both scalp and body ringworm and samples (preferably collected by the brush technique) submitted for mycological assessment, even in the absence of clinical signs.9 If the source is a cat or dog, family pets should be screened by a veterinary surgeon.5 Information should be provided to all parents and staff in the child’s school, so that other infected children can be identified promptly. If more than two children in a class are infected, others in the class should, with parental consent, be screened by scalp brushing.6 This method of obtaining samples is recommended because of the difficulties in screening large numbers of children.

Treatment principles

The aim of treatment is to eradicate scalp ringworm quickly, to relieve symptoms, to minimise potential long-term irreversible scarring, and to reduce the likelihood of transmission to others. In practice, this will typically mean starting treatment before culture results become available, but this should be done only if clinical suspicion is high. Contacts, whether carriers or infected people, should also be treated.6 In theory, infected children could infect others at school. However, an infected child is likely to have been at school for some time before the infection has been detected, so exclusion from school is probably too late to prevent spread.6

Systemic treatment

Oral antifungal drugs are the mainstay of treatment in children with scalp ringworm. The use of such therapy might also be justified in carriers with a very heavy growth on brush culture, both to prevent transmission to others and prevent the development of overt symptoms and signs (even though the drugs are not licensed for such use).9Four oral antifungals are used in the treatment of scalp ringworm in children – griseofulvin, terbinafine, fluconazole and itraconazole. Only griseofulvin, the longest-standing treatment, is specifically licensed in the UK for scalp ringworm in children. Terbinafine is increasingly recommended as the first treatment for T. tonsurans infections,6 but is not licensed for use in children for any indication. However, it is licensed for fungal infections of the skin (but not specifically tinea capitis) in adults. Fluconazole is licensed for use in children for some fungal infections, but is explicitly not licensed for tinea capitis in any age group. Itraconazole is licensed for dermatophytosis (e.g. Microsporum and Trichophyton species) in those aged 12 years or more (but not specifically tinea capitis).

Griseofulvin

Griseofulvin is available as tablets (e.g. 125mg), and as an unlicensed suspension (125mg/5mL) via specialist importing companies. Alternatively, some pharmacies will supply an extemporaneous preparation of crushed (non-film-coated)tablets of griseofulvin suspended in a suitable liquid (again, an unlicensed formulation).6 The dose given in the British National Formulary for Children (BNFC) for tinea capitis due to T. tonsurans in children aged 1 month to 12 years is 15–20mg/kg (maximum total 1g)either once daily or in divided doses;for children aged 12–18 years, the dose is 1g either once daily or in divided doses.12 Standard advice is to give treatment for at least 6–8 weeks.6

Published randomised controlled trials have found that a 6–10 week course of oral griseofulvin (10–20mg/kg body weight) will usually clear scalp ringworm infection (clinically and mycologically).5,1315

Common unwanted effects of griseofulvin include nausea, vomiting, diarrhoea, headache and rash.12 Pregnancy should be avoided during and for 1 month after treatment because of evidence of fetotoxicity and teratogenicity in animals, and males should avoid fathering a child during and for at least 6 months after treatment. Griseofulvin reduces the contraceptive effect of the oral contraceptive pill by accelerating the metabolism of both oestrogens and progestogens.12

Terbinafine

Terbinafine is available as 250mg tablets, making it hard to use on a dose per weight basis. For instance, the once-daily dose given in the BNFC for tinea infections in children aged more than 1 year weighing 10–20kg is 62.5mg and 20–40kg is 125mg.12 In children over 40kg, the dose is 250mg.12 The drug is usually given for 4 weeks.12

A meta-analysis of six randomised controlled trials involving a total of 603 patients with scalp ringworm and comparing the use of terbinafine (doses as listed in the BNFC12, given for between 2 and 12 weeks) with griseofulvin concluded that a 2–4 week course of terbinafine was at least as effective as a 6–8 week course of griseofulvin for the treatment of Trichophyton infections (odds ratio 0.84, 95% CI 0.54–1.32, p = 0.462).15

Common unwanted effects with terbinafine include gastrointestinal symptoms (e.g. dyspepsia, abdominal discomfort, loss of appetite, nausea, diarrhoea), headache and allergic skin reactions (rash and urticaria).16 Very rarely, there have been cases of cholestatis and hepatitis reported with terbinafine, and the SPC recommends that, if hepatic dysfunction develops, treatment should be stopped.16

Fluconazole

Fluconazole is available as a powder for oral suspension (e.g. 50mg/5mL) and capsules(e.g. 50mg). The dose given in the BNFC for tinea infections (not including tinea capititis) in children aged from 1 month to 18 years is 3mg/kg (maximum total 50mg) daily for 2–4 weeks (maximum 6 weeks).12 This is less than that used in published trials in patients with scalp ringworm (i.e. 5–6mg/kg daily13,14,17).

A double-blind randomised controlled trial involving 880 children (aged 3–12 years)with scalp ringworm(mainly due to T. tonsurans) compared fluconazole (6mg/kg daily for 3 weeks) followed by placebo for 3 weeks; fluconazole (6mg/kg daily for 6 weeks); or griseofulvin (11mg/kg daily for 6 weeks).17The analysis was based on the modified intention-to-treat population(i.e. those with a positive fungal culture at baseline), and, where patients’ data were unavailable, their last recorded result was used. After 6 weeks of treatment the combined outcomes in terms of success (total clinical and mycological cure)plus partial success(mycological cure and improvement in symptoms) were similar for fluconazole 6mg/kg daily and griseofulvin 11mg/kg daily (48.0% vs. 51.3%, p = 0.32). The success rates may have been so low because the follow-up did not last long enough.

Another single-blind randomised controlled trial involving 40 children (aged 1–16 years)with scalp ringworm(mainly due to Trichophyton species) compared fluconazole (5mg/kg daily for 4 weeks) with griseofulvin (15mg/kg daily for 6 weeks).14 At 8 weeks, the complete cure rate was similar with fluconazole and griseofulvin (78.9% vs. 76.2%, relative risk [RR] 1.04, 95% CI 0.74–1.45).

Common unwanted effects with fluconazole therapy include nausea, abdominal discomfort, diarrhoea, flatulence, headache and rash.14 The summary of product characteristics (SPC) advises that liver function should be monitored with high doses or an extended course and the drug discontinued if there are any signs or symptoms of liver disease.18 It also advises that the drug should be avoided in pregnancy.

Itraconazole

Itraconazole is available as 100mg capsules, making it hard to use on a dose per weight basis. For instance, the dose given in the BNFC for tinea infections (not including tinea capitis) in children aged from 1 month to 12 years is 3–5mg/kg (maximum total 100mg) once daily for 15–30 days.12For 12–18 year-olds, the dose is either 100mg once daily for 15–30 days or 200mg once daily for 7 days.12

In a double-blind randomised controlled trial, itraconazole (100mg daily) was compared with griseofulvin (500mg daily) in 34 children and 1 adult with scalp ringworm (mainly due to Microsporum species).19 Both drugs were given for 6 weeks. The final evaluation was made 8 weeks after the end of treatment (i.e. at 14 weeks) to allow hair to regrow. A similar number of patients were cured (either no residual signs and symptoms or mild signs such as erythema or alopecia, plus negative microscopy and culture) with each drug (88% with itraconazole vs. 88% with griseofulvin, RR 0.94, 95% CI 0.80–1.09).

Another double-blind randomised controlled study, involving 55 patients with scalp ringworm (mainly due to Trichophyton species), compared daily itraconazole (50mg for a weight below 20kg; 100mg for 20–40kg; and 200mg for over 40kg) and terbinafine (62.5mg for a weight below 20kg; 125mg for 20–40kg; and 250mg for over 40kg), each given for 2 weeks.20 The assessment of efficacy was based on the combined evaluation of mycological results and the sum of clinical scores at week 12. This showed no difference in cure rate between the treatments(85.7% with itraconazole and 77.8% with terbinafine, p>0.05).

The most common unwanted effects with itraconazole are gastrointestinal, hepatic and dermatological.21 The SPC advises that liver function monitoring should be considered and treatment with itraconazole discontinued if there are any signs or symptoms of hepatic disease.21 Following rare reports of heart failure, the former Committee on Safety of Medicines(CSM)has advised “caution” when prescribing itraconazole to patients at high risk of heart failure.12 The SPC advises that the drug should only be used in pregnancy in life-threatening situations, and that effective contraception should be used during treatment and until the next menstrual period following the end of treatment.21

How the drugs compare

A single-blind randomised controlled trial, lasting 12 weeks and involving 200 children with scalp ringworm (due to Trichophyton species), compared griseofulvin (20mg/kg daily for 6 weeks), terbinafine (62.5–250mg for 2–3 weeks), fluconazole (6mg/kg daily for 2–3 weeks) and itraconazole (5mg/kg daily for 2–3 weeks).13 At the end of the study, effective treatment (i.e. mycological cure [negative culture], and either complete clinical cure or only a few residual symptoms) was similar with all four drugs: 92% with griseofulvin vs. 94% with terbinafine vs. 84% with fluconazole vs. 86% with itraconazole (p = 0.33).

A systematic review has pooled data from 21 randomised controlled trials involving a total of 1,812 participants to assess the effects of systemic antifungal drugs for tinea capitis in children (i.e. under the age of 18 years).22 The reviewers reported that terbinafine for 4 weeks and griseofulvin for 8 weeks resulted in similar cure rates when results were pooled from five studies (a total of 643 children; RR 1.11, 95% CI 0.96–1.29). They also found that cure rates in two trials (134 children) were similar for itraconazole for 2–3 or 6 weeks and griseofulvin for 6 weeks (RR 0.94, 95% CI 0.80–1.09); in two trials (255 children) were similar for itraconazole and terbinafine, both for 2–3 weeks (RR 0.93, 95% CI 0.72–1.19); and in two trials (240 children) were similar for fluconazole for 2–3 or 4–6 weeks and griseofulvin for 4–6 weeks (RR 0.92, 95% CI 0.80–1.05). Pooled analysis of four studies (549 children, 3 adults) comparing different treatment durations of terbinafine showed that 4 weeks was better than 2 weeks (RR 0.81, 95% CI 0.68–0.96) or 1 week (RR 0.6, 95% CI 0.55–0.8). The reviewers concluded that “newer treatments including terbinafine, itraconazole and fluconazole may be similar to griseofulvin in children with tinea capitis caused by Trichophyton species”, and that “all have reasonable safety profiles”.

Approximate cost to the NHS based on a 20kg child*

*Based on information in the Drug Tariff

**Doses as given in British National Formulary for Children

***Where a tablet is split, price is based on discarding any unused tablet.

Topical antifungals

Topical antifungals do not penetrate the infected hair follicle sufficiently, and so are generally considered inadequate as sole treatments for scalp ringworm.5 There is a lack of robust evidence for their effectiveness and we know of no published trials comparing topical and oral antifungals. A single uncontrolled study of 16 children with T. tonsurans suggested complete clearance of scalp ringworm in 33% of the children with 2% ketoconazole shampoo applied daily for 8 weeks.23 Also, in a non-blinded randomised trial involving 54 patients, both 1% and 2.5% selenium sulphide shampoo applied twice weekly reduced the surface colony counts of tinea.24 Topical antifungals are used as an adjunct to oral therapy to reduce the frequency of positive cultures during the early stages of treatment and limit the spread of infection.6,9They are also recommended for use in people with mycological evidence of carriage but no symptoms.5,6

Follow-up and referral

Ideally, patients should be seen at least at the end of treatment to assess clinical clearance and a repeat mycological sample taken to confirm mycological cure.9If primary treatment fails, the patient should be referred to a specialist.

Conclusion

Scalp ringworm continues to be a significant health issue in the UK. Anyone with the condition needs to be treated with an oral antifungal drug. Also, all close contacts of patients should be screened for infection or carriage. Griseofulvin is the longest-established antifungal drug for scalp ringworm and the only one licensed for this condition in children. Evidence indicates that the newer antifungals, terbinafine, fluconazole and itraconazole, are similarly effective to, and as well tolerated as, griseofulvin, and require shorter courses of treatment. Terbinafine is increasingly recommended as the first-line treatment for Trichophyton tonsurans, now the most common cause of the infection in the UK. It is also the least expensive. However, we are concerned that the drug has not been licensed for children despite evidence of effectiveness. In addition, the lack of a suitable preparation of terbinafine to enable easy administration on a dose per weight basis (as is also the case with itraconazole) creates problems for prescribers and patients. For these reasons, fluconazole seems a reasonable alternative. Topical antifungals are not effective treatment on their own in infected individuals, but can be used alone in carriers or as an adjunct to oral therapy in those with scalp ringworm to reduce the spread of infective spores. However, data to support their use are limited.

References

[M=meta-analysis; R=randomised controlled trial]

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