Fungal Fun Facts: Ringworm (dermatophytosis)

Ringworm is a condition most people have at least heard of at some point in their lives. Although worm is in the name, it is actually caused by a fungal organism. This particular fungus is found throughout most environments. They thrive on eating skin cells. The classic shape is a ring that almost has the appearance of a worm which is how it was originally named.

 

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Due to its hardy nature in the environment most animals are susceptible to contracting this fungus. The most commonly affected seem to be young animals or animals with a compromised immune system. Once infected, they will continue to shed spores throughout the environment that can be used to infect others or continue to re-infect the original host. This is very important to remember when treating ringworm as it can be transmitted to people.

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Symptoms include circular lesions of hair loss or crusting. They can be found anywhere but the most common location includes the face especially around the nose. It is generally not itchy, however rare cases will show intense scratching.

 

Wood's lamp detecting ringworm (image source)

There are several methods of diagnosis. A wood’s lamp can be used to examine the skin around the lesion. The fungus will show up as a bright green area. This is not 100% accurate but can be useful and inexpensive test. If negative other tests need to be pursued. If positive, treatment can be instituted. Other tests include culture of the hair follicles. If growth on the culture media is noted then it can be examined under a microscope for a definitive diagnosis. Another option would be a biopsy. Where a sample of the skin is taken and submitted for histopathology. This is analysis of very small skin segments with special stains to identify the cause of the lesions.  

Culture plates of fungal spores (image source)

Treatment must be applied to the animal (or people affected) and the environment. There are many options for treatment and working with your veterinarian will determine which will be best for your. If localized a cream may work when applied to that area. If the infection persists or is a large area oral antifungal medications may be best option. Once in the home environment strict decontamination needs to be instituted. Without rigorous treatment of the environment it is likely for the infection to keep coming back. Treatment should be continued until two negative fungal cultures are obtained one month apart from each other.

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One final note is that some animals are called asymptomatic carriers. So they do not demonstrate any hair loss or crusting but can continue to pass it to other animals and people in the house. Cultures may be necessary to determine if the pet is a carrier. For more information on ringworm please click here.