Ringworm

Ringworm

Causative Agent

A potentially zoonotic disease of the skin, hair or nails caused by one of several species of fungi (dermatophytes). Some of these fungi are adapted to soils (e.g., Microsporum gypseum), others to animals and humans (e.g., M. canis, Trichophyton verrucosum). Both can potentially cause disease in animals and humans.
“Worms” have nothing to do with this disease.

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Characteristic ringworm lesions are often round, devoid of hair and red in colour as demonstrated in this mule deer.

Distribution

Geographic:

Seasonality:

Hosts, Transmission and Life Cycle

Hosts:

Humans and wild mammals: in BC, ringworm has been reported in black-tailed and mule deer, and small carnivores.
Young mammals, and those suffering from other diseases or with reduced immunological competence may be prone to severe ringworm infection.
Some species of fungus are adapted to specific hosts and many of these infections in well-adapted species appear without symptoms. Such species can act as “reservoirs of infection”.

Transmission and Life Cycle:

Through direct contact with fungal material on carrier animals or contact with fungal spores from objects such as feed, bedding, etc., especially on abraded skin.
Ringworm infection is usually self-limiting with lesions taking a few weeks to several months to regress depending on the fungal species, degree of host adaptation and response of the individual host. Secondary bacterial infections of the skin can be extensive and debilitating.

Signs and Symptoms

Ringworm skin lesions typically begin as distinct, round areas of hair loss, which may then progress to skin reddening, thickening and loss of pigmentation.
Breakage of the hair shaft and subsequent hair loss is accomplished by fungal elements entering the shaft of the hair itself, rendering it brittle.

Meat Edible?

Human Health Concerns and Risk Reduction

Ringworm infection in humans is similar to that in wildlife but infections may be more severe.
Skin lesions are often red, expansive, and can vary from dry and scaly to moist and seeping fluid. Lesions may also have a central healed zone surrounded by expanded “ring” of infection – hence “ringworm”.
Rubber gloves should be worn when handling wildlife with skin conditions. The area in which the infected animal was handled should also be decontaminated with household bleach in a 1:10 dilution.
Topical application of antifungal agents, sometimes for extended periods, is the usual mode of treatment.

Samples for Diagnosis

Presence of fungal infection can be confirmed in the laboratory with skin samples, skin scrapings, or hair samples.

Similar Diseases

Viral diseases such as pox, bacterial diseases causing inflammation of the hair follicle, and parasitic infections such as sarcoptic mange may present similar clinical signs.