At a glance
- Ringworm (tinea or dermatophytosis) is a common epidermis infection caused by dermatophyte fungi.
- Ringworm spreads easily through direct skin contact among people and animals or by fomites.
- Onychomycosis (fungal nail infection) can cause discomfort and occasionally leads to serious secondary bacterial infections, especially in people with diabetes.
- Clinicians should use diagnostics to confirm infections, especially before prescribing antifungal treatment.
- Antimicrobial-resistant ringworm and onychomycosis are an emerging public health concern.
Types
The most common species of fungi that cause ringworm are Trichophyton, Microsporum, and Epidermophyton. Ringworm is characterized by the part of the body affected.
Ringworm is often described by the site of the body affected. Examples include:
- Ringworm of the scalp (tinea capitis)
- Ringworm of the groin (tinea cruris or jock itch)
- Ringworm on the feet (tinea pedis or athlete's foot)
Onychomycosis is the term for fungal nail infections. It can be caused by ringworm or by infection with other types of fungi such as yeasts. Onychomycosis can affect the fingernails or toenails, but onychomycosis of the toenails is more common.
How it spreads
Symptoms usually start 4-14 days after exposure. Ringworm also sometimes spreads from one part of the body to another.
Ringworm of the skin is spread through:
- Direct skin contact with people and animals who are infected.
- Sharing personal items (e.g., towels, clothing, bedding).
- Contact with moist surfaces, like shower stall or locker room floors.
Ringworm of the nails usually spreads through a small cut in the skin around the nails. Infections on the foot or between toes are common with nail infections.
Disease rates
It is estimated that up to 25% of people in the world may experience ringworm at some point in their lifetime.
Onychomycosis is estimated to affect around 14% of the general population and is especially common in older adults. People with diabetes are at increased risk for fungal nail infections.
Clinical features
Skin
The classic ringworm lesion is an erythematous, raised, scaly ring with central clearing. Multiple lesions might be present. The severity of ringworm infections can range from mild, scaly lesions to erythematous, exudative lesions if a bacterial superinfection has developed.
Avoid corticosteroid creams
Nail infections
Most cases of onychomycosis are not serious. However, some people may experience pain or be bothered by the appearance of their nails. Onychomycosis may cause nails to become discolored, thick, fragile, or cracked. The nail may also become separated from the nail bed.
People who have fungal toenail infections often have a fungal skin infection on the foot, especially between the toes.
Occasionally, a bacterial infection can occur on top of a fungal nail infection and cause serious illness. This is more common in people with diabetes or other conditions that weaken the immune system.
Test for fungal infections
Ringworm may be difficult to distinguish from other skin conditions, like psoriasis and eczema. These conditions require different treatments which may include corticosteroid creams which should be avoided for fungal infections. There are also many potential causes for fingernail and toenail abnormalities.
Healthcare providers are recommended to test for ringworm and other fungal skin or nail infections to determine best treatment. Diagnosis and appropriate treatment support antifungal stewardship efforts and prevent the spread of antimicrobial resistance.