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What is Ringworm?

Unlike its name suggests Ringworm (dermatophytosis) is actually not a worm it is a type of infectious fungal disease involving the hair, skin and nails/claws.

Microsporum canis is the most common fungus responsible for the infection, accounting for 94-99% of feline infections.

How is infection spread?

The infective stage of the ringworm fungus is the spore. Spores are microscopic and therefore cannot be seen with the naked eye. They can be spread to a healthy animal by direct contact with an infected animal, or indirectly via a contaminated environment or inanimate object (such as clothing). They can be carried on air currents, dust particles, and fleas. Spores can remain viable in the environment for up to 18 months.


Any cat that comes into contact with spores is at risk for developing ringworm; however, there is increased risk associated with being very young or very old, poor nutrition, presence of external parasites (eg. fleas), immunosuppression (eg. FIV), and living in multi-cat facilities/households. Long haired cats, especially Persians and Himalayans are also at increased risk of developing the disease.

The incubation period (the time between infection and appearance of signs of disease) is usually 10 to 14 days however can take up to 6 weeks.


What are the signs of infection?

The signs of infection are extremely variable however a common presentation is an irregular or circular patch of peripherally expanding hair loss with scale, crusting and sometimes redness of the skin. The face and forelimbs are most commonly affected, especially in kittens.


How is it diagnosed?

Use of a Wood’s lamp is a commonly used, quick and easy technique that may be used in the diagnosis or ringworm; however, this may result in detection of approximately only 40% of cases. Fungal culture is also commonly used and is regarded as the most reliable diagnostic test; however, it can take up to 4 weeks to get results. Due to these difficulties that can be encountered with diagnosis, treatment may be initiated without a definitive diagnosis.

How is it treated?

Ringworm is considered a self-limiting disease (most healthy cats that do not receive treatment will recover within several months) however it is usually treated for the following reasons:

- To minimize the risk of spreading to people
- To minimize the risk of spreading to other animals
- To decrease contamination of the environment
- To minimize the severity and duration of lesions of those infected.

Treatment usually involves topical medication (eg. Malaseb) and oral medication. Topical creams (eg. Canesten) are not recommended as it can encourage the animal to lick the area and spread the lesions.

Can Ringworm be spread to people?

Yes. Ringworm is a zoonotic disease (a disease of animals that can be transmitted to humans), and is spread to people in the same manner as for cats. Exposure to the organism does not necessarily result in infection; however, there is an increased risk of developing infection in people that are immunosuppressed, very young, or very old.

The signs of infection in people are ring shaped areas of scaling and hair loss, with or without redness, crusting and itching. If you are at all concerned you have developed ringworm please visit your GP.

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