Ringworm is not a worm at all and is not just for cats either. Ringworm is a fungal organism that occurs in humans and in animals. While fairly benign in most cases, children and immunosuppressed people are more susceptible. The following discussion on signs, diagnosis and treatment of ringworm will help you manage this problem in your pets.
Ringworm is a fungal skin lesion in the dermatophyte family. It is not creepy little worm that lives under the skin, as the name suggests. It is common in cats and in people, and the spores can be found in most environments. Because it can easily be transferred between species it is considered zoonotic. This fungal organism is closely related to dandruff and tinea, or athlete’s foot in humans.
Ringworm in animals causes patchy areas of hairloss, with damaged broken hairs. The skin often has a circular rim around the edges of the lesion. It can be slightly crusty or flaky, but is not usually itchy. The typically circular red ring that appears in humans is how it got the name ringworm. Sometimes the presentation is a little more unusual, and in some cases the areas around the nail beds are affected.
Ringworm can come directly from a cat or from the environment. Spores are very resistant and can survive more than a year in the right conditions either indoors or outdoors. Most environments will have low numbers of dermatophytes, particularly in soil, but this becomes a problem if an infected animal (whether that be a pet, pest or native animal) is shedding large numbers of infective spores. Sometimes cats are blamed unnecessarily, however up to 20% of cats can be asymptomatic carriers, and most cases of ringworm are the species that cats tend to carry. If you do happen to get any interesting skin lesions visit your doctor and take your cat to the vet. Your cat may be carrying the fungal spores, but not actually showing any signs, so it is important to identify the source of the infection. If your cat is not positive for ringworm, it is likely you got it from somewhere else (another animal or from the environment).
Firstly visit your vet who will recommend some tests to make sure it is ringworm. Many skin problems can look very similar, so even if your skin looks similar to those pictures on the internet, make sure you have the right diagnosis. Isolate any cats who have skin lesions to avoid spreading the spores throughout the house and avoid contact with elderly, children or immunosuppressed people (such as those undergoing treatment with immunosuppressive drugs, chemotherapy or with HIV/AIDS). Although most people only develop very minor skin irritations from ringworm, those that do not have a competent immune system can develop serious disease, even lung problems.
Your Veterinarian may use a special lamp called a Wood’s lamp to help diagnose ringworm. This test involves holding an ultraviolet light over the lesion and looking for bright green fluorescence. A negative Wood’s lamp test does not completely rule out ringworm, as only 50% of species will glow, but it is a good first step. Your Vet may then get some samples of hairs either via a toothbrush or from the lesions and place them on a special fungal culture medium. It takes 14 days to rule out ringworm via a fungal culture, so your Vet may recommend antifungal treatment in the meantime just in case. For more unusual patches of skin it may be necessary to perform a biopsy to diagnose ringworm.