Winter 2003

Zoonoses - Ringworm

Ringworm (Microsporum canis) infection in a German Shepherd dog (Photo obtained from a book)

There are many different species of ringworm and they come from different sources: animals, man and the environment. The most common agent is Microsporum canis, however a variety of different species result in symptoms of infection.   “Ringworm” is transmitted to man by direct or indirect contact with infected cats, dogs, humans, or contaminated materials. Infections are often unapparent, especially in cats and dogs. Some species will fluoresce under a Wood’s (ultraviolet) lamp but others do not so a negative test result is not necessarily a negative ringworm result.

A fungal culture can be done on your pet if it has lesions that are suggestive of ringworm. This test does take over a week for the fungus to grow & to produce a positive or negative result however.

Ringworm occurs in various locations on the human body: groin, feet, nails, scalp and beard, and the lesions may vary in appearance. Ringworm of the scalp and beard usually presents as one or more scaly, grey patches of alopecia or hair loss.

There may be a pustular folliculitis or granulomatous lesion. The primary lesion of ringworm of the body is a small red macule which spreads outwards with an inflammatory “ring-like” border and healing centre.

Treatments include griseofulvin (a fungal antibiotic) and / or topical fungicides and sterilisation of contaminated clothing and articles.

It is important that affected people don’t share clothing with others.

Barry