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Dermatomycosis

Many species of animals are susceptible to fungi that cause the condition known as ringworm. Dogs, cats, and domestic livestock are the most commonly affected animals. The skin lesion usually spreads in a circular manner from the original point of infection, giving rise to the term "ringworm". The complicating factor is that cats and rabbits may be asymptomatic carriers of the pathogens which can cause the condition in humans. Dermatophyte spores can become widely disseminated and persistent in the environment, contaminating bedding, equipment, dust, surfaces, and air, resulting.

The dermatophytes have a cosmopolitan distribution; some dermatophytes have a regional geographic concentration. These organisms cause ringworm in humans and animals, which continues to be common among dogs, cats, and livestock. In the United States, several dermatophytes of animal origin are involved in the superficial mycoses of humans, including Microsporum canis, Trichophyton mentagrophytes, and T. verrucosum. M. canis is most prevalent in dogs, cats and nonhuman primates and in human infections associated with these species, but it can also occur in rodents.

Trichophyton mentagrophytes has been associated more commonly with ringworm in rodents and rabbits and occurs among laboratory personnel who work with these species and agricultural personnel who work around granaries, barns, and other rodent habitats. T. verrucosum is restricted generally to cases of ringworm in livestock and their agricultural attendants.

In humans, the disease usually consists of focal, flat, spreading annular lesions that are clear in the center, and crusted, scaly, and erythematous in the periphery. Lesions often are on the hands, arms or other exposed areas, but invasive and systemic infections have been reported in immunocompromised people.

The use of protective clothing, disposable gloves, and other appropriate personal hygiene measures are essential for the control of this zoonosis in a laboratory animal facility.