Causes and Risk Factors of Ringworm

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Ringworm has nothing to do with actual worms. Rather, the red, ring-shaped rash, clinically known as tinea, is a fungal infection. It's highly contagious and spreads easily. Often, all you have to do to catch ringworm is to touch someone or something that may have been infected. Sometimes you can even get a fungal infection by touching the soil.

ringworm causes and risk factors
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Common Causes

There are more than 40 species of fungi that can cause ringworm, according to the Centers for Disease Control and Prevention (CDC). These fungi are known as dermatophytes. Specific dermatophytes associated with the various types of ringworm, including athlete's foot, jock itch, tinea capitis (a fungal infection of the scalp), and others include Trichophyton, Microsporum, and Epidermophyton.

Dermatophytes thrive in warm, moist areas of the body where they feed on dead keratin, skin cells on the epidermis and in nails and hair.

The infections they cause are highly contagious and can easily be transmitted by skin-to-skin contact—that is, by touching someone who has a fungal infection.

Ringworm can infect animals as well, and so when an infected pet—especially a new puppy or kitten—joins a household the human family members are at risk. If you adopt a pet, it's vital to have it thoroughly examined by a veterinarian, but do look for signs of ringworm yourself: circular areas where there's no fur or where the coat is brittle or has broken hairs and the skin is scaly, red, or crusty.

Dermatophyte fungi can thrive on inanimate surfaces as well. They produce spores that are shed into the infected child's clothing, brushes or combs, and even into the air around the child. These spores can survive for months on objects. 

This means, for example, that it's possible to become infected by borrowing a hairbrush or a cap from someone with tinea capitis (ringworm of the scalp) or by going barefoot in an areas where someone with athlete's foot has been walking or standing, such as in a shower stall or gym locker room.

Children are especially susceptible to ringworm and other skin rashes. People born with weak immune systems or who have compromised immune systems due to illness such as HIV/AIDs or certain medications, including corticosteroids or chemotherapy drugs, also have an increased risk of fungal infections.

Lifestyle Risk Factors

Health habits and other behaviors can put you at an increased risk of developing ringworm and other fungal infections. These include:

  • Not washing your hands frequently when around someone or something that might have been exposed to a fungus
  • Having damp skin for extended periods of time—for instance, not showering and drying off completely after sweating a lot
  • Minor skin and nail injuries
  • Close contact with others who have ringworm, such as sharing a room or spending time in a classroom with someone who's infected.
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  1. Centers for Disease Control and Prevention. People at Risk for Ringworm | Ringworm | Types of Diseases | Fungal Diseases | CDC. Aug 6, 2018.

  2. Nenoff P, Handrick W, Krüger C, et al. [Dermatomycoses due to pets and farm animals : neglected infections?]. Hautarzt. 2012;63(11):848-58. doi:10.1007/s00105-012-2379-y

  3. J. Dvořák, Z. Hubálek, M. Otčenášek. Survival of Dermatophytes in Human Skin Scales. JAMA Otolaryngol Head Neck Surg. 2015;141(5):428. doi:10.1001/archderm.1968.01610170100021

  4. Toukabri N, Dhieb C, El euch D, Rouissi M, Mokni M, Sadfi-zouaoui N. Prevalence, Etiology, and Risk Factors of Tinea Pedis and Tinea Unguium in Tunisia. Can J Infect Dis Med Microbiol. 2017;2017:6835725. doi:10.1155/2017/6835725

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