Ringworm, also known as tinea or dermatophytosis, is a common fungal infection affecting the skin, hair, and nails in both humans and animals. The term “ringworm” is misleading because it is caused by mold-like fungi, not a parasitic worm. The characteristic name comes from the itchy, circular, ring-shaped rash that often develops. This contagious infection is classified as a zoonotic disease when transmitted from animals to humans, which includes cattle. Transmission from cows to humans is a known risk in agricultural settings, making this a specific concern for farmers, veterinarians, and anyone with close contact with livestock.
The Specific Fungus Transmitted by Cattle
The primary agent responsible for ringworm in cattle, and the one most commonly spread to humans, is the dermatophyte fungus Trichophyton verrucosum. This species is highly adapted to bovine hosts and accounts for over 90% of cattle ringworm infections. When humans contract ringworm from cattle, T. verrucosum is the dominant cause.
Like other dermatophytes, T. verrucosum thrives on keratin, the protein found in the outer layer of skin, hair, and nails. The fungus can survive for extended periods outside of a host in the environment. Its spores are hardy and remain viable on contaminated surfaces, such as barn walls, bedding, or equipment, for many months or even years. This environmental persistence makes the infection difficult to control in a herd setting. The spores spread through hair and skin scales shed by infected animals.
How Infection Spreads and Human Symptoms
Infection spreads to humans through both direct and indirect contact with cattle. Direct contact involves touching an infected animal during activities like milking, feeding, or grooming. The fungus easily penetrates the skin, especially if small cuts or abrasions are present.
Indirect transmission occurs when a person touches contaminated objects or surfaces. This includes contact with fences, stalls, gates, halters, clothing, or soil where infected animals have been. Young children can be infected indirectly simply by being in the barn or farm environment, even without directly touching the animals.
Ringworm acquired from cattle often results in a more inflammatory and severe reaction in humans compared to common human-to-human ringworm. The lesions appear as raised, scaly, and red patches that are itchy. Because the fungal species is highly inflammatory, the patches may also develop blisters, pustules, or thick crusts.
The infection commonly presents on areas of the body that contacted the animal or contaminated surfaces. In adults, this frequently includes the upper limbs, hands, and forearms. In children, the scalp or face can also be affected, especially if they hug or lean on the animals. When the scalp is involved, it can lead to kerion, a painful, boggy, pus-filled swelling that may cause permanent scarring and hair loss if not treated promptly.
Prevention and Treatment Protocols
Preventing the spread of ringworm relies heavily on strict hygiene and environmental control. Livestock handlers should wear dedicated work clothes, gloves, and boots when handling animals, especially those showing signs of infection. Washing hands and forearms thoroughly with soap and water immediately after contact with cattle, equipment, or the barn environment is a primary preventative measure.
Environmental sanitation is important because the fungus survives for long periods outside the host. Regular cleaning and disinfection of stalls, equipment, and housing areas with a potent antifungal agent reduces the spore load. Monitoring the herd for ringworm signs and isolating or treating infected animals, particularly susceptible calves, helps limit the source of human infection.
If a person suspects ringworm, they should consult a healthcare professional for diagnosis. For mild cases on the body, topical antifungal creams containing ingredients like clotrimazole or miconazole are prescribed and applied for several weeks. These over-the-counter treatments are typically effective if used consistently.
More severe, extensive, or inflammatory infections, particularly those affecting the scalp or not responding to topical treatment, require oral antifungal medications. Prescription drugs like terbinafine or fluconazole are taken by mouth to eliminate the fungus from hair follicles and deeper skin layers. The full course of oral medication must be completed as prescribed to prevent recurrence.