What is hand fungus?
Hand fungus is medically referred to as tinea manuum, which means “ringworm of the hand”. It is caused by a class of fungi known as dermatophytes. The literal meaning of the term dermatophyte is “skin plant”, and it refers to the tendency of these fungi to grow on the skin. Hand fungus may affect either one or both of the hands. Tinea manuum is less common than fungal infections of the feet (tinea pedis ) and the nails (tinea unguium). Dermatophyte infections are commonly referred to as ringworm infections because they appear as round or oval rashes on the skin. In addition to the hands and nails, these ringworm infections also occur on the body (tinea corporis) and the feet (tinea pedis).
Signs and Symptoms
Hand fungus typically appears as a skin rash on the hands and the fingers. This rash can have the following features:
- Itch: The rash in tinea manuum is intensely itchy.
- Dry skin: The dryness of the skin may result in peeling. This is most commonly seen in infections due to anthropophilic fungi.
- Reddish ring: The main visible characteristic of tinea manuum is a ring-shaped rash that is circumscribed with a raised reddish border.
- Blisters: Patches of tiny blisters may arise on the hands and fingers. These blisters may also start oozing.
- Skin discoloration: When a chronic rash heals, the skin in the affected region might appear to be discolored.
The characteristics of hand fungus may not be unique. Many times, the presentation is similar to that of other skin conditions such as contact dermatitis, psoriasis, and dyshidrotic eczema. Hand fungus may also occur in the aftermath of these other skin conditions.
Pictures of Hand Fungus
Causes of Hand Fungus
A healthy skin is the first line of defense against pathogens that seek to enter the body. The surface of the skin contains a layer of dead cells. It is also made waterproof by a protein called keratin. This structure helps the skin resist invasion by most pathogens, who usually gain entry into the body if the skin is unhealthy and broken at some place (e.g. due to cuts and abrasions). The skin also has the ability to heal itself in many cases.
Dermatophytes have the ability to break the skin barrier due to the keratinase enzymes that they produce. These enzymes chew up the protective keratin layer of the skin and allow the fungus to establish itself in the skin. The infection is usually superficial, affecting only the outermost layers of the skin. However, it can grow over time if left untreated.
Dermatophyte infections are contagious. They can pass on to uninfected individuals from already infected individuals (anthropophilic). Moreover, they can also be passed onto humans from infected animals (zoophilic) or from the soil (geophilic). The most common way that the hands get infected with ringworm is by scratching another infected body part such as the feet or the groin.
Types of Fungi
Hand fungus could result from infection with a variety of different dermatophytes. Following are some of the main causative fungi:
- Anthropophilic fungi: Anthropophilic fungi have a predilection for the human skin. These are the most common dermatophytes that cause tinea manuum. Some examples include Trichophyton rubrum, Trichophyton interdigitale, and Epidermophyton floccosum. T. rubrum is the most common cause of fungal infections on the human skin.
- Zoophilic fungi: Zoophilic fungi get transmitted to humans through contact with animals such as pet dogs and cats. Examples include Microsporum canis and Trichophyton verrucosum. Microsporum canis is transmitted through contact with cats and dogs, wheras Trichophyton verrucosum is transmitted through contact with cattle.
- Geophilic fungi: Fungi causing skin infections can also be transmitted through contact with contaminated soil. Microsporum gypseum is an example of such a fungus.
Hand fungus can occur in any person. However, it is more likely to be contracted by individuals with the following risk profiles:
- Those people who have a pre-existing skin infection are more likely to get hand fungus. This is due to the itchy nature of the fungal skin infections. Scratching the infected body parts could spread the fungus to the hands and the fingers.
- People who are in close contact with already infected persons are more likely to get hand fungus. Sharing of clothes and towels between infected and non-infected individuals is a likely route of transmission.
- Individuals who sweat profusely (a condition known as hyperhidrosis) are prone to getting fungal skin infections, including hand fungus.
- People who are suffering from other skin diseases such as allergic contact dermatitis are also prone to catching hand fungus. These skin diseases make the skin susceptible to establishment of fungal infections.
- Regular and close contact with pets such as cats and dogs also increases the likelihood of getting skin infections, including hand fungus. Children are more susceptible to this risk factor.
- Farm workers who come in regular contact with cattle and contaminated soil in the farms are also exposed to the risk of contracting hand fungus.
- Gardeners, manual laborers and garbage pickers get exposed regularly to contaminated soil and inanimate objects that could lead to hand fungus.
Diagnosis of Hand Fungus
In most cases, the diagnosis of hand fungus is based on the characteristic appearance of the rash. Other skin conditions that can result in a skin rash with a similar appearance also need to be ruled out. Skin scrapings, fungal cultures and skin biopsy could also be used to determine the characteristics of the hand fungus. One of the tell-tale signs of hand fungus is the presence of identical fungal skin infections on both the feet. In such cases, the hand fungus is more likely to be present on the dominant hand that is used for scratching the feet.
Treatment of Hand Fungus
Anti-fungal medication, either topical or systemic, is the primary treatment for hand fungus. Some topical anti-fungals include clotrimazole, ciclopirox and econazole. Some of the oral anti-fungal medications include fluconazole, griseofulvin and terbinafine. Recurrence of hand fungus can be prevented by treating and managing the underlying predisposing conditions.