Ringworm is common and 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 highly 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.
Most people are exposed to the causes of ringworm daily. However, some people are more susceptible to it than others. Those who suffer from eczema or other skin ailments, as well as pre-pubescent children, are more vulnerable to the infection.
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 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 spots may become evident. The affected area may become itchy for periods of time.
Doctors can diagnose ringworm on sight, or they may take a skin scraping. The tissue 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.
Sometimes a ringworm infection may cause skin lesions in a part of the body that is remote from the actual site of the disease. Such lesions are called "dermatophytids." The lesions themselves are fungus-free and frequently 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.