Ringworm spreads through direct contact with an infected person, animal, or surface. Despite the name, it’s not a worm at all. It’s a fungal infection caused by organisms called dermatophytes that feed on keratin, the tough protein in your skin, hair, and nails. These fungi pass easily between hosts because they produce spores that are remarkably durable, surviving on surfaces, fabrics, and even in soil for weeks or longer.
How the Fungus Takes Hold
Dermatophytes are uniquely adapted to live on skin. They secrete a chemical compound called sulfite that breaks apart the bonds holding keratin together, essentially dissolving the outer layer of your skin to use it as food. Because keratin is rich in the amino acid cysteine, the fungus converts that cysteine into more sulfite, creating a cycle that lets the infection expand outward in the characteristic ring shape.
Once the spores land on your skin, symptoms typically appear between 4 and 14 days later. The classic sign on the body is a red, circular patch with raised edges and clearing in the center. On the scalp, it looks more like patchy scaling or dandruff-like flaking, sometimes with hair loss.
Person-to-Person Contact
The most common way ringworm travels between people is direct skin-to-skin contact. Any situation where your bare skin touches an infected area on someone else creates an opportunity for transmission. This is why ringworm is so prevalent in contact sports like wrestling and football, where athletes press against each other repeatedly during practice and competition. The New Jersey Department of Health guidelines specifically flag these sports as high-risk environments.
You can also pick it up indirectly by sharing towels, clothing, hairbrushes, helmets, or other personal items that touched an infected person’s skin. Locker rooms and communal showers are common hotspots because people walk barefoot on wet surfaces where spores can linger.
Animals Are a Major Source
Pets and livestock are responsible for a large share of human ringworm cases, and the animal doesn’t always look sick. Cats are the single biggest animal source in urban areas. They frequently carry the fungus without showing obvious symptoms, making them silent spreaders. Dogs, rabbits, guinea pigs, and hamsters can all transmit it as well.
Different animals tend to carry different strains. Cattle are the primary hosts for one common species, while horses carry another. Hedgehogs are well-known carriers of their own strain, and even chickens can harbor the fungus. Hunting dogs are at particular risk because they encounter wild rodents like voles and mice that carry dermatophytes in their fur. Any time you handle, pet, or groom an infected animal, spores can transfer to your skin.
Contaminated Surfaces and Objects
What makes ringworm particularly persistent is how long the spores survive outside a living host. Research published in the Journal of Fungi found that dermatophyte spores remained viable after freezing, after exposure to 60°C heat for 90 minutes, and even after running through a standard home dryer cycle. In laboratory conditions, freeze-dried fungal cultures have stayed alive for over 12 years with no loss of viability.
This means everyday objects can act as reservoirs. Gym mats, shared helmets, bedding, furniture, carpeting, and clothing can all harbor infectious spores long after the infected person or animal has moved on. Wrestling mats are a classic example, which is why sports programs are advised to disinfect them after every single practice and multiple times a day during tournaments.
What About Soil?
Some dermatophyte species live naturally in soil. In rare cases, prolonged contact with heavily contaminated soil can cause infection. This is not a common route for most people, but gardeners or others who spend extended time with their hands or bare skin in dirt could theoretically be exposed.
How Long Someone Stays Contagious
An untreated ringworm infection remains contagious the entire time lesions are present. Once antifungal treatment begins, the contagious window shrinks quickly. After 48 hours of treatment, ringworm generally does not spread to others. Wrestlers are typically cleared to return to competition after 3 days of topical antifungal use, provided the lesion can be covered.
Scalp infections are a different story. They’re harder to treat and require at least 14 days of therapy. Fungal spore shedding from the scalp can continue well beyond two weeks, so medicated shampoo before practices or group activities helps reduce transmission even after treatment has started.
Cleaning Fabrics and Surfaces
Given how tough these spores are, you might assume you need harsh chemicals to kill them on laundry. Surprisingly, research from the Journal of Feline Medicine and Surgery found that washing contaminated textiles twice in cold water on a long cycle (at least 14 minutes per wash) was enough to decontaminate them. Adding bleach made no measurable difference. The mechanical action of the wash itself, combined with detergent, did the work.
For hard surfaces like gym equipment, countertops, and bathroom floors, regular cleaning and disinfection remain important. Shared equipment should be wiped down after each use and allowed to dry completely before the next person touches it. Daily cleaning of locker rooms and shower areas is standard guidance for athletic programs.
Who Gets Infected Most Easily
Anyone can get ringworm, but some people pick it up more readily. Children are especially susceptible, partly because of close contact during play and partly because their immune defenses are still developing. People with weakened immune systems face higher risk and may develop more stubborn infections. Athletes in contact sports are repeatedly exposed in exactly the conditions the fungus thrives in: warm, moist skin pressed against other skin or shared surfaces.
Practical steps that reduce your risk come down to limiting the fungus’s opportunities. Shower immediately after sports or gym sessions. Wear sandals in locker rooms and public showers. Don’t share towels, razors, helmets, or clothing. Keep sports gear clean between uses. If you have pets, watch for bald patches or crusty skin and get them checked, especially cats that spend time outdoors or around strays.