1 Condition: Tinea corporis (ringworm).

Cause: Topical fungal infections are caused by dermatophytes, organisms that invade and proliferate on the outermost, horny layer (stratum corneum) of the skin, hair and nails. They do not normally penetrate deeper into the skin or tissues, and they tend to thrive in areas of the body that are occluded and moist.

The common infecting organisms are Trichophyton, Microsporum and Epidermophyton species.

Features: Itchy pink or red scaly patches with a well-defined, inflamed border. Lesions are often paler at the centre, becoming progressively inflamed towards the outer edge.

Lesions typically occur on exposed skin of the trunk, arms and legs, often singly but can be multiple and sometimes overlap to form a large continuous patch. Infection is often transmitted by animals (pets or livestock) and can also be picked up from the soil.

Treatments: Imidazoles: clotrimazole, econazole and miconazole. They act by inhibiting the biosynthesis of ergosterol, a constituent of the fungal cell membrane, resulting in disruption of the cell. They also possess activity against Grampositive bacteria, which is useful, as secondary bacterial infection can complicate fungal infection. Treatment for up to one month may be necessary to ensure complete eradication.

Terbinafine: An allylamine derivative with a broad spectrum of antifungal activity. It is available as a 1% cream which is applied once or twice daily for one week, a 1% gel which is used once daily for 1 week, and a cutaneous solution (licensed only for tinea pedis, see below) which requires only a single application. The treatment regimen for imidazoles and terbinafine is the same for adults and children.

Advice: Avoid close contact with pets and farm animals, and wash skin areas that may have been in contact with them as soon as possible afterwards. Avoid touching or sharing towels with an infected person.