Fungal skin infections are superficial infections of the skin caused by parasitic fungi. They are very common and can affect all parts of the body. Although they generally pose no health risk, they can be tricky to eliminate and may recur often in individuals who are prone to them.
- Understanding fungal skin infectionsFungal infections are caused by the excessive proliferation of microscopic fungi on the skin.
These fungi fall into two categories:
• Dermatophytes: these keratinophilic fungi are responsible for fungal infections of the skin, skin folds, nails and hair. Dermatophytes can be of human or animal origin, or present in soil. They are contagious and can be transmitted through direct contact with the infected source, skin debris, contaminated hairs, or by walking barefoot on a wet floor. They then penetrate the top layer of the skin (corneal layer), where they produce mycelial filaments by eating away at the keratin, which is essential to their growth.
• Yeasts such as Candida (usually Albicans) and Malassezia are responsible for certain fungal infections of the skin folds, nails and mucous membranes. Candida Albicans are naturally present in the digestive tract and the genital mucous membranes, but they create superficial skin infections when they propagate on the skin.
Likewise, Malassezia live in the skin’s pilosebaceous follicles normally, but become problematic when they proliferate excessively.
Humidity, heat and confinement (which leads to maceration), a lack of hygiene, or skin lesions provide the perfect breeding grounds for fungal infections. Certain diseases (diabetes, for example), certain medications, a weak immune system, and blood circulation problems also make individuals more prone to fungal infections.
- The different types of fungal skin infectionsFungal infections can affect different parts of the skin and take a variety of forms:
• Ringworm (tinea corporis)
Resulting from a contamination by dermatophytes, this type of fungal skin infection can affect any hairless part of the body (glabrous skin): the face, neck, torso, arms and legs. It is characterised by the appearance of round, red patches in varying sizes, in the shape of rings with a scaly edge. These patches are generally very itchy.
• Ringworm of the foot (tinea pedis)
Ringworm of the foot is very common and is most often caused by dermatophytes, but yeasts can also sometimes be involved. The infection generally starts between the toes: the skin peels and cracks appear but do not heal.
If left untreated, the fungal infection spreads to the sole, edges and back of the foot. It becomes an extensive red-edged scaly patch with rounded contours. Often, it is itchy. We call this “athlete’s foot”.
• Fungal infection in the skin folds
Also called fungal intertrigo, this fungal infection is caused by both dermatophytes and candida. It can affect the small folds (interdigital spaces of the hands and feet, lips) and the large ones alike (groin, between the buttocks, fold under breasts, armpits). The fold in question becomes red and cracked. Patches appear which are scaly around the edges and sometimes covered in a white or yellowish deposit.
Small fold fungal infections commonly occur in individuals who sweat a lot or are frequently in contact with water. Wearing professional safety shoes or sport shoes regularly can also cause them to appear.
Large fold fungal infections are caused by perspiration and skin rubbing against clothing. They are more common in overweight individuals.
• Pityriasis versicolor (tinea versicolor)
Resulting from a Malassezia yeast proliferation on the skin, pityriasis versicolor manifests as small, rounded brown or buff-coloured patches, which peel individually, then spread and join up to form larger patches over time. In certain cases, white patches can also appear following sun exposure.
- Treating fungal skin infectionsNowadays, highly effective treatments exist against fungal infections. Early intervention is important to stop the infection from spreading: see your skin specialist at the first signs.
Your doctor will decide on your treatment based on the extent of the fungal infection, its location, the number of sites infected, and your medical history. Generally, local antifungals are used. These are applied to the lesions for one or more weeks, and are sometimes combined with oral medication. To achieve a full recovery, the treatment instructions with regards to regularity and duration must be strictly followed. If you are regularly subject to fungal infections, your doctor might also prescribe an antifungal maintenance treatment to better control the frequency of recurrences.
To learn more about fungal nail infections, please refer to the page dedicated to this topic.
M. Feuilhade de Chauvin. Mycoses métropolitaines. Encycl Méd Chir (Elsévier, Paris), Dermatologie, 12-320-A-10, 1998, 10p.
C. Lacroix M. Feuilhade de Chauvin . In Thérapeutiques dermatologique, L. Dubertret, Médecines-Sciences, Flammarion, Paris, 2001.p 182.