Athlete’s foot, or tinea pedis, is a common fungal infection of the foot caused by a group of fungi…
What is tinea?
Tinea refers to a group of fungal skin infections that includes athlete's foot, jock itch and 'ringworm' (which is not due to a worm, but rather a fungus that causes ring-shaped rashes). It can occur anywhere on the body, but most commonly affects the feet, scalp and fingernails. Its appearance depends on what type of tinea it is (see 'Types' below).
Tinea is caused by a group of fungi called dermatophytes that live on the outer layer of skin. They use a component of skin, called keratin, as an energy source. The severity of your symptoms usually depends on the species and strain of fungus that is causing the infection.
Tinea is contagious and can be spread through direct contact with an infected person, or through contact with contaminated objects or surfaces, such as towels, shoes or communal showers.
Some factors that can increase the chance of developing tinea include:
- Damp, humid, crowded conditions;
- Close contact with an infected person;
- Sweating excessively;
- Sharing clothing, towels or linen;
- Wearing tight clothing, and;
- Having a weak immune system or certain underlying medical conditions, such as type 2 diabetes.
Tinea corporis affects the skin on the body, and is commonly called ringworm. It commonly appears as ring-shaped, red rashes, which are also itchy.
Tinea pedis affects the foot, and is commonly known as athlete's foot. It can cause itchy blisters between the toes and on the side on the foot, and dry, scaly patches on the sides and sole of the foot
Tinea cruris affects the groin, and is commonly known as jock itch. It causes a red, itchy, raised rash in the groin that can also spread down the inner thighs.
Tinea capitis affects the scalp and results in small lumps of raised skin that then flake off and can cause temporary baldness.
Tinea unguium affects the nails on the toes and fingers, and is otherwise known as onychomycosis. It causes the nails to gradually thicken and become discoloured. Over time they can become brittle and eventually disintegrate.
Methods for diagnosis
Tinea can be diagnosed by an examination of your skin or nails. A scraping of skin or clipping of nail from the affected area can also be sent for testing to confirm the diagnosis. The following tests can be performed on these samples:
Potassium hydroxide exam
The sample is added to potassium hydroxide (KOH) and examined under a microscope. Potassium hydroxide destroys non-fungal cells, making it easier to see if any fungal cells are present.
If fungus is present on the skin, it can be cultured using a special gel (agar) plate that selectively grows it. Fungi can two weeks or more to grow. The benefit of fungal cultures is that it can also determine the most effective treatment option.
Types of treatment
Tinea is usually treated with topical antifungal creams, such as ketoconazole and terbinafine, which are applied directly to the affected area. Sometimes an oral antifungal medication, such as oral terbinafine or fluconazole, can be prescribed for infections that do not respond well to topical cream. Continuing treatment is usually needed, even after an infection has cleared, to prevent it from returning. It is also important to treat all sites with the fungal skin infection simultaneously, to prevent re-infection in the future.
Although tinea can usually be cured, it is common for it to return. Tinea spreads easily to other parts of the body. Severe cases can sometimes result in breaks in the skin that can cause permanent scarring or a bacterial infection.
Maintaining good hygiene by washing and drying the skin properly, washing linen and towels in hot water and not sharing them with others can help prevent the spread of tinea. You can also reduce your risk of getting tinea on your feet by not walking barefoot in public spaces such as showers, gymnasiums and swimming pools.