Ringworm is very common, especially among children, and may be spread by skin-to-skin contact, as well as via contact with contaminated items such as hairbrushes or through the use of the same toilet seat as an infected individual.Ringworm spreads readily, as those infected are contagious even before they show symptoms of the disease. Participants in contact sports such as wrestling have a risk of contracting the fungal infection through skin-to-skin contact.
Ringworm is mildly contagious. Ringworm is also a common infection in domestic animals, especially farm animals, dogs and cats. Humans can contract ringworm from these animals as humans are in close contact with them. Chickens may also be a source, due to the dirty conditions in which many poultry must live in which ringworm may thrive. Ringworm can also be caught from other humans, both by direct contact and by prolonged contact with flakes of shed skin (from sharing clothes or from house dust, for instance).
To catch ringworm, you have to be exposed to it and you have to be susceptible. Some people are much more susceptible than others. Those with eczema or other skin problems get ringworm more easily because the protective barrier of the skin's outer layer is less intact. Children are more susceptible before puberty. Some people are genetically predisposed, and can get it easily throughout life.
Symptoms and diagnosis
The best known sign of ringworm in people is the appearance of one or more red raised itchy patches with defined edges, not unlike the herald rash of Pityriasis rosea. These patches are often lighter in the center, taking on the appearance of a ring. If the infected area involves the scalp or beard area, then bald patches may become evident. The affected area may become itchy for periods of time.
Plucked hair treated with KOH showing ectothrix spores and hyphae from a case of feline ringworm.
Doctors can diagnose ringworm on sight, or they may take a skin scraping, or in the case of animal ringworm or tinea capitis, examine plucked hairs for fungal elements. This is examined under a microscope, or put on an agar plate in a microbiology laboratory and allowed to grow. Specialized agar plate, called Dermatophyte Test Medium is used to culture and identify ringworm organisms.
Some of the fungi fluoresce under a black light examination.
In domestic animals, ringworm can cause a variety of symptoms, but most cases show scaling and patches of hair loss. Some cats can be carriers, but show no symptoms.
Sometimes a ringworm infection may cause skin lesions in a part of the body that is remote from the actual infection. Such lesions are called "dermatophytids". The lesions themselves are fungus-free, and normally disappear upon treatment of the actual infection. The most common example is an eruption in the hands resulting from a fungus infection of the feet. Dermatophytids are essentially a generalized allergic reaction to the fungus.