As podiatrists we are very accustomed to seeing adults with fungal nail infections but what about in children? This blog looks at research into onychomycosis in this age group. Thank you to podiatrist Tim Veysey-Smith who inspired a review of this subject following some discussion on the topic.
Onychomycosis in children was once considered a rare occurrence but recent literature has suggested that it is probably increased in prevalence. As we know, fungal nail infection in adults is not uncommon with the condition closely associated with pre-existing tinea pedis. A range of studies have attempted to quantity this through surveys of the general population, hospital patients and laboratory samples. Population based studies are thought to reflect the true prevalence of the condition in the community. Data from a review in 2014 suggested a rate in adults of around 4.3% in North America and Europe, with a rate double this in hospital based studies (8.9%) (1). A small number of studies and reviews have investigated the rate of nail infection in children. Rates of between 0.6% and 2.6% have been reported, with only slight regional variation (2). Gupta in 2015 suggested a rate of 0.14% in children (3) compared with 10.3% in adults (3).
Onychomycosis in a child.
(Reproduced from Kim et al., 2013 under the creative commons licence)
Reasons for lower rates of dermatophyte toenail infection are unknown but it has been suggested that it is lower than in adults because of the faster rate of nail growth eliminating infection. Also, children have lower rates of concomitant tinea pedis, fewer co-morbidities, less accumulated nail trauma and infrequent exposure to causative fungi (2). Dissecting childhood onychomycosis rates further, the data shows, as with adults, the figure increases significantly with age. Adolescents having the highest rates, whilst infection in infants is considered rare (2). Like adults, males seem to be more affected twice as much as females (4). In addition, a previous study examining onychomycosis in children under two showed it to be more prevalent in children with immune-suppressive disorders such as HIV infection and Downs syndrome as well as preterm infants (5). Downs Syndrome being known to affect T and B cell function (6).
Clinical Presentation & Diagnosis
The clinical presentation of onychomycosis in children is similar to adults. Infection most often begins in a distal lateral presentation of invasion with the causative agents similar to adults with toenails being most often affected (7) although this tends to be more often single digit disease (4). Typical infecting organisms in this age group are T rubrum and T mentagrophytes (8, 9). The risk factors for the development of childhood onychomycosis include (4, 10, 11):
· Having a sibling or parent with the infection
· Living in a smaller home
· Rural setting
· Older age (adolescents)
· Sporting activities
· Having tinea pedis
Distal and lateral sub-ungual onychomycosis is the by far the most common presentation of the infection. In adults it is often quoted 50% of all nail dystrophy involves fungus (12), but this figure is much lower in children around 15% (13) and so careful assessment is required. In young patients, nail changes may be a result of onychomycosis but they also may accompany skin conditions such as lichen planus, eczema, psoriasis and ichthyosis making clinical diagnosis tricky. A good history and examination can help to elucidate the existence of skin disease. The use of appropriate mycological testing such as microscopy, culture, PCR or dermatophyte (lateral flow) test strip (14) is strongly advocated to ensure a clear diagnosis of fungal infection to prevent inappropriate treatment.
Management
Where there is any doubt in the diagnosis, where concomitant disease is suspected or specialist treatment is required, referral to a dermatologist maybe appropriate, particularly for younger children. Treatment of onychomycosis in children is not significantly different than in adults although some of the available drugs may not be licenced for use in children. In the UK, amorolfine is the only licenced topical medicine available for the treatment of onychomycosis in children. There is no clinical data on its effectiveness for children, although it has been suggested that topical therapy is more effective in children than adults, possibly because of thinner nails permitting more penetration by the topical agents (2, 10). Anecdotally, nail reduction prior to application of the lacquer may also improve its effectiveness as demonstrated in adults (15, 16).
Oral treatment of fungal nail infection in children is less well researched than in adult populations. Itraconazole and terbinafine are used but with reduced dosing regimens for younger children. These are generally prescribed by specialist consultants. A systematic review assessed 7 studies involving the treatment of 208 children with onychomycosis in children and concluded that there was a low rate of mild adverse events with evidence of effectiveness (17).
References
1. Sigurgeirsson B, Baran R. The prevalence of onychomycosis in the global population – A literature study. J Eur Acad Dermatol Venereol. 2014;28(11):1480-91.
2. Solís-Arias MP, García-Romero MT. Onychomycosis in children. A review. Int J Dermatol. 2017;56(2):123-30.
3. Gupta AK, Daigle D, Foley KA. The prevalence of culture-confirmed toenail onychomycosis in at-risk patient populations. J Eur Acad Dermatol Venereol. 2015;29(6):1039-44.
4. Kim DM, Suh MK, Ha GY. Onychomycosis in children: an experience of 59 cases. Annals of dermatology. 2013;25(3):327-34.
5. Bonifaz A, Saúl A, Mena C, Valencia A, Paredes V, Fierro L, et al. Dermatophyte onychomycosis in children under 2 years of age: experience of 16 cases. J Eur Acad Dermatol Venereol. 2007;21(1):115-7.
6. Castellanos J, Toledo-Bahena M, Mena-Cedillos C, Ramirez-Cortes E, Valencia-Herrera A. Onychomycosis in Children with Down Syndrome. Current Fungal Infection Reports. 2018;12(4):207-12.
7. Gupta AK, Sibbald RG, Lynde CW, Hull PR, Prussick R, Shear NH, et al. Onychomycosis in children: prevalence and treatment strategies. J Am Acad Dermatol. 1997;36(3 Pt 1):395-402.
8. Romano C, Papini M, Ghilardi A, Gianni C. Onychomycosis in children: a survey of 46 cases. Mycoses. 2005;48(6):430-7.
9. Lange M, Roszkiewicz J, Szczerkowska-Dobosz A, Jasiel-Walikowska E, Bykowska B. Onychomycosis is no longer a rare finding in children. Mycoses. 2006;49(1):55-9.
10. Feldstein S, Totri C, Friedlander SF. Antifungal therapy for onychomycosis in children. Clin Dermatol. 2015;33(3):333-9.
11. Rodríguez-Pazos L, Pereiro-Ferreirós MM, Pereiro Jr M, Toribio J. Onychomycosis observed in children over a 20-year period. Mycoses. 2011;54(5):450-3.
12. Faergemann J, Baran R. Epidemiology, clinical presentation and diagnosis of onychomycosis. Br J Dermatol. 2003;149 Suppl 65:1-4.
13. Gupta AK, Paquet M. Systemic Antifungals to Treat Onychomycosis in Children: A Systematic Review. Pediatr Dermatol. 2013;30(3):294-302.
14. Tsunemi Y, Takehara K, Miura Y, Nakagami G, Sanada H, Kawashima M. Screening for tinea unguium by Dermatophyte Test Strip. Br J Dermatol. 2014;170(2):328-31.
15. Harkless L, Pollak R, Jennings M, Weisfield M, Shebetka K, Pfister P, et al., editors. Study design of the IRON-CLAD trial:efficacy and safety of 12 weeks of oral terbinafine with and without nail debridement in the treatment of toenail onychomycosis. Poster presentation at FIP World Congress; 2004; Boston, USA.
16. Sumikawa M, Egawa T, Honda I, Yamamoto Y, Sumikawa Y, Kubota M. Effects of foot care intervention including nail drilling combined with topical antifungal application in diabetic patients with onychomycosis. J Dermatol. 2007;34(7):456-64.
17. Gupta AK, Mays RR, Versteeg SG, Shear NH, Friedlander SF. Onychomycosis in children: Safety and efficacy of antifungal agents. Pediatr Dermatol. 2018;35(5):552-9.