Ringworm (Tinea Infections)

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Introduction

Ringworm is a common superficial fungal infection which affects the skin.1

The infection is colloquially called β€œringworm” because lesions are often circular-shaped. Despite this name, ringworm is not a parasitic worm infection.

Ringworm can also be referred to as tinea or dermatophytosis. Ringworm is more common in hot and humid environments.1

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Aetiology

Ringworm (tinea) is caused by dermatophytes (a type of fungus).Β 

Depending on the location, the condition can be referred to as:1,2,3

  • Tinea capitis (affecting the scalp)
  • Tinea pedis (affecting the feet)
  • Tinea cruris (affecting the groin)
  • Tinea corporis (affecting any other skin site)

In the community, ringworm of the feet may be called β€œathlete’s foot”, while ringworm of the groin may be called β€œjock itch”.

Common species of dermatophyte include T. rubrum, T. interdigitale and T. tonsurans.

Zoonotic species such as M. canis, T. verrucosum, T. equinum and T. erinacei may be present in those that interact with animals.1


Risk factors

Ringworm is spread by skin-skin contact or contact with an infected surface.

Risk factors include:

  • Male sex
  • Contact with an infected person
  • Frequent use of communal shower facilities
  • Not drying feet adequately (risk of tinea pedis)

The most at-risk groups include children attending daycare and early school and households of an infected person.

Medical risk factors are those primarily relating to an immunocompromised state or skin condition affecting the skin’s barrier, and include:1,2

  • Previous tinea infections
  • Diabetes mellitus
  • Hyperhidrosis
  • Xerosis (dry skin)
  • Ichthyosis

Clinical features

History

Typical symptoms of tinea corporis include:1,2,3

  • An asymmetrical rash consisting of solitary circular erythematous patches with a raised scaly leading edge and a clearing centre (hypopigmentation within the ring) (Figure 1)
  • Itch

Β Other important areas to cover in the history include:1,2,3

  • Social history: usually affects children in daycare or early school years
  • Infectious contacts: either as a classmate, carer or household contact
  • Other risk factors: frequent use of communal showers, pools or gyms, athletes
  • Contact with animals

Clinical examination

Typical clinical findings will vary depending on the location of the fungal infection:1,2,3

  • Body (tinea corporis):Β asymmetrical rash that appears as solitary circular erythematous patches with a raised scaly leading edge and hypopigmentation within the ring. (Figure 1).
  • Scalp (tinea capitis): often begins as a pimple that grows, creating dry, scaly, bald patches of skin. Associated with brittle hair and hair loss at sites of infection. It can crust over and often be mistaken for dandruff.
  • Feet (tinea pedia): results in dry and cracked skin between the toes, with a scaling rash that can move proximally if not treated.
  • Nails (tinea ungium): results in nail beds that are thickened, keratotic, dry, brittle and cracking
  • Groin (tinea cruris): appears as annular plaques over the groin folds

 


Differential diagnoses

Ringworm can be mistaken for other dermatological conditions. Differential diagnoses to consider in the context of ringworm include:2

  • Discoid (nummular) eczema: plaques tend to be confluent, less likely to have central clearing (hypopigmentation) within plaques, steroid-responsive
  • Annular psoriasis: lesion scale is silver, pitting of nails, family history of psoriasis
  • Pityriasis rosacea: yeast infection, a patch of infection often preceded by a generalised rash
  • Pityriasis versicolour: confluence of hypopigmented lesions, no scaling at the leading edge, unresponsive to topical antifungals
  • Subacute cutaneous lupus erythematosus: more common in females, distribution in photosensitive areas
  • Erythema annulare centifugum: a trailing as opposed to a leading scale pattern to lesions

Investigations

Ringworm is aΒ clinical diagnosis.

A skin scraping of the leading edge may be taken to confirm the diagnosis, especially in cases which do not respond to initial anti-fungal treatment. Skin scrapings can be sent for microscopy, culture and sensitivities. Any topical therapy must be removed before collecting scrapings. Hair and nail cuttings may also be used.1

A Wood’s lamp can examine hair as affected hairs will fluoresce green.1

Treatment-resistant or atypical presentations may require a skin biopsy.


Management

Topical therapy

The first line of management is topical therapy:4

  • Topical terbinafine 1%: formulated as a cream (body, scalp, feet, nails), gel (body, scalp, groin), spray (interdigital, body, scalp) or liquid (interdigital). Used once or twice daily for one to two weeks.
  • Econazole (or a similar azole) cream: applied once or twice daily for two weeks.

Oral therapy

Oral therapy is the next-line treatment option if the infection is severe, affecting multiple sites, recurrent, or not responding to topical treatment.4

The first option is oral terbinafine 250mg daily for adults. For children under 20kg, the dose is 62.5mg daily. For those 20 – 40 kgs, it is 125mg daily.

The length of treatment is dependent on the site of infection:

  • Scalp: four weeks
  • Fingernails: six weeks
  • Toenails: 12 weeks
  • Other body sites: two weeks

The next option is griseofulvin (for tinea of the hair and scalp only) for 4-6 weeks and up to 1 year:

  • Scalp/hair/groin: 500mg daily
  • Feet/nails: 1 g daily

The last line of therapy is oral fluconazole or itraconazole.Β 


Complications

Complications most commonly arise in the immunosuppressed.2,3

The most common complication is secondary bacterial co-infection with Staphylococcus aureus.3,4

Those with untreated HIV/AIDS can experience a disseminated infection that can affect any organ, including the brain leading to serious cerebral complications and even death if treatment is not commenced in time.3,4Β 


Key points

  • Ringworm, known as tinea, is a common dermatophyte (fungal) infectionΒ which can affect several body sites.
  • Clinical features vary depending on theΒ location of the infection. Tinea corporis typically presents with an itchy characteristic circular rash (with a raised scaly leading edge and a clearing centre)
  • It is a clinical diagnosis but can be confirmed by using skin scrapings.Β 
  • First-line treatment is topical anti-fungal agents, and oral therapy can be used in severe or resistant cases.Β 
  • Bacterial co-infection is the most common complication and is more likely to occur in immunocompromised patients.

Reviewer

Dr Mark Graydon


Editors

Dr Jasmine Handford

Dr Chris Jefferies


References

  1. Dermnet NZ. Tinea corporis. Available from [LINK]
  2. Kovitwanichkanont, T., & Chong, A. H. (2019). Superficial fungal infections.Β Australian Journal of General Practice,Β 48(10), 706-711.
  3. The Royal Children’s Hospital Melbourne. Ringworm. 2020. Available from [LINK]
  4. AMHΒ  Online. Tinea. 2022. Available from: [LINK]
  5. DermNet. Typical annular lesions of Ringworm. Licence: [CC BY-NC-ND 3.0 NZ]
  6. DermNet. Tinea capitis. Licence: [CC BY-NC-ND 3.0 NZ]
  7. DermNet. Tinea pedis. Licence: [CC BY-NC-ND 3.0 NZ]

 

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