Ringworm is a skin infection caused by a fungus. Fungi are plant-like organisms that feed on living tissue, including human skin.
Tinea fungal infections are caused by a particular type of fungi, called dermatophytes, which live off keratin.
Keratin is a tough, waterproof tissue found in many parts of your body, including your skin, hair and nails.
This explains why fungal infections mostly affect your skin, scalp or nails.
How it spreads
The fungi are tiny spores tough enough to survive for months on your skin, in soil or on household objects, such as combs or towels. They thrive in heat and moisture, which helps them to grow and explains why they are often spread in swimming pool changing rooms and communal showers. The spores can be spread in four different ways:
- human-to-human contact
- human-to-animal contact – for example, by stroking an infected dog or cat
- human-to-object contact – both animals and humans can leave traces of fungi spores on objects and surfaces, such as towels, clothing, bed linen, combs or brushes
- human-to-soil contact – less commonly, it can develop after lengthy exposure to infected soil
As an adult, you can become a carrier of a scalp infection without developing any symptoms. This is because your body has usually developed a defence against the infection by the time you reach adulthood.
If you’re a carrier of a fungal infection, you can unknowingly pass the condition on to children, who may then go on to develop symptoms.
You are more likely to develop a fungal infection if you:
- are very young or very old
- are African-Caribbean (in the case of scalp infections)
- have type 1 diabetes
- are very overweight (obese)
- have a medical condition that weakens your immune system, such as HIV or AIDS
- are receiving medical treatment that weakens your immune system, such as chemotherapy or steroid tablets
- have had fungal infections in the past
- have hardened arteries (atherosclerosis)
- have poor circulation (specifically, a condition called venous insufficiency, where the veins in your legs have trouble moving blood back to your heart)