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Throughout the world, dermatophytosis (ringworm) is an important zoonosis [26]. This symposium attempts to highlight significant epidemiological features of these infections, to discuss mycological and laboratory aspects of the causal dermatophytes including an unusual pathogen of sheep, and to comment on current therapeutic options for the treatment of infected humans. Aetiology and public health significance of animal ringwormDermatophytes can conveniently be divided into three ecological groups depending on their natural animal or environmental hosts: (i) anthropophilic species which have humans as the normal host; (ii) zoophilic species which normally occur in other animals; and (iii) geophilic species whose natural habitat is still the soil [26]. Under appropriate conditions zoophilic and some geophilic species are transmissible to humans. The main zoophilic dermatophytes and their common hosts are listed in Table 1; only three species, Microsporum canis, Trichophyton verrucosum and Trichophyton mentagrophytes, are consistently recovered from human disease.On a geographical basis, zoophilic dermatophytes tend to be more common as human pathogens in temperate to colder areas of the world, although exceptions do occur (e.g.M. canis is uncommon in the Chicago area of the USA) [20]. Also, in some areas (e.g. Australia) where M. canis has been the dominant agent of childhood tineas, other fungi such as the anthropophilic Trichophyton tonsurans are now emerging as equally significant agents of tinea capitis [21]. Reasons for this are unclear, although it does seem that this may be associated with a decline in the incidence of cat and dog ringworm in these areas. A summary indicating the importance of M. canis, T verrucosum and the animal varieties of T. mentagrophytes (vat. mentagrophytes, var. erinacei and var. quinckeanum) in human ringworm on a worldwide basis is shown in Table 2. Although potential animal reservoirs are present in many tropical areas of the world, zoophilic tineas are uncommon in humans in such regions; reasons for this are unknown, although it seems that the degree and closeness of animal to human contact is a major factor.It is also apparent that most infected and/or significantly colonized animals appear clinically normal. In one survey in New Zealand [2], 36% of cats and 7"5% of dogs examined routinely (by a skin brushing technique) were found to be carriers of M. canis