Dermatophytosis is a superficial fungal infection of the skin, nails, and hair, commonly known as “ringworm.” This name is a misnomer, as the condition is caused by fungi called dermatophytes, not a worm, and refers to the characteristic ring-shaped rash that can form. While not a serious health threat, dermatophytosis can cause discomfort and is contagious.
Common Types and Symptoms
Tinea Corporis (Ringworm of the Body)
Tinea corporis can appear nearly anywhere on the body and is responsible for the classic “ringworm” presentation. It forms a circular or oval-shaped patch of red, scaly skin. This patch features a raised border that expands outward, while the skin in the center may clear, creating the ring-like appearance. The rash is itchy, and multiple patches can appear simultaneously.
Tinea Pedis (Athlete’s Foot)
Tinea pedis, or athlete’s foot, develops in the warm, moist environment between the toes. This leads to skin that appears scaly, peels, and cracks. The infection causes persistent itching and a burning sensation in the affected areas. It can also cause small, fluid-filled spots and may spread to the soles of the feet.
Tinea Cruris (Jock Itch)
This infection affects the groin, inner thighs, and buttocks, areas prone to moisture and warmth. Tinea cruris presents as a red, itchy rash with a defined, scaly border, similar to tinea corporis. It is more common in males and can be aggravated by sweat and tight-fitting clothing.
Tinea Capitis (Ringworm of the Scalp)
Tinea capitis affects the scalp and hair shafts and is most frequent in children. It results in itchy, scaly, circular patches on the scalp. The infection causes hairs in the affected area to become brittle and break, leading to patches of hair loss. A more severe inflammatory reaction called a kerion, a swollen, pus-filled lesion, can develop and may lead to scarring if not treated.
Causes and Transmission
Dermatophytosis is caused by dermatophytes, a group of molds that feed on keratin. Keratin is the protein found in the outer layer of skin, hair, and nails. By metabolizing keratin, these fungi survive on the body’s surfaces without invading deeper tissues. The most common fungi responsible for these infections are Trichophyton, Microsporum, and Epidermophyton.
Direct skin-to-skin contact with an infected individual is a primary mode of spread. This is common in activities involving close physical contact, like wrestling. Fungal spores shed from an infected person’s skin can establish an infection on another person.
Animals are another source of transmission. Pets like cats and dogs, as well as farm animals, can carry dermatophytes on their skin and fur and pass them to humans. An animal may not show obvious signs of infection but can still be a carrier.
Contact with contaminated objects and surfaces is another transmission route. Dermatophytes can survive on items such as towels, clothing, combs, and footwear. Damp environments like public showers, locker rooms, and pool areas are common places to acquire the fungi by walking barefoot.
Diagnosis and Treatment Options
A healthcare provider can diagnose dermatophytosis by visually examining the affected skin, hair, or nails. The characteristic appearance of the rash is a strong indicator. To confirm the diagnosis, a doctor may take a small sample of the affected skin or nail.
The sample is examined using a KOH test, which uses potassium hydroxide to dissolve human cells, making fungal elements visible under a microscope. If the diagnosis is uncertain or the infection is not responding to treatment, the sample may be sent for a fungal culture. This process grows the fungi in a special medium to identify the specific species causing the infection.
Treatment varies based on the infection’s location and severity. For most skin infections, like athlete’s foot or ringworm, over-the-counter (OTC) topical antifungal medications are effective. These are available as creams, powders, or sprays with active ingredients like clotrimazole or miconazole.
For persistent or widespread infections, a doctor may prescribe a stronger topical antifungal. Oral antifungal medications are necessary for severe infections, or those on the scalp (tinea capitis) or nails (tinea unguium). These medications, such as terbinafine and itraconazole, are taken by mouth to eliminate the fungus.
Prevention and Management
Good personal hygiene is important for preventing dermatophytosis. Keep the skin clean and dry, as fungi flourish in moist conditions. Pay special attention to skin folds, like the groin and between the toes, ensuring they are dried thoroughly after bathing.
Avoid sharing personal items like towels, razors, clothing, and hairbrushes. Fungi can linger on these objects, facilitating transmission from one person to another. Using your own items reduces the risk of contact with infectious fungi.
In communal, damp environments, protect your feet. Wearing waterproof footwear, like flip-flops or shower shoes, in public showers, locker rooms, and around swimming pools prevents contact with fungi. Regularly changing socks and underwear also helps keep susceptible areas dry and clean.
If a pet is suspected of having a fungal infection, seek veterinary care. Treating the infected animal prevents animal-to-human transmission and eliminates a source of infection for the household.