Background: Dermatophytes can be divided into geophilic (soil), zoophilic (animals) and anthropophilic (human) strains, depending on the source of the keratin. The predominant organisms vary within a given geographical region during different periods, which is influenced by a number of factors, such as population movements, socioeconomic circumstances and level of surveillance. Thus, the incidence is very variable.
Aim: To determine the epidemiology of superficial fungal infections due to zoophilic and geophilic fungi in patients referred to the Pasteur Institute of Iran.
Methods: The clinical presentation of zoophilic and geophilic dermatophyte-related infections was reviewed retrospectively from the medical records of all subjects referred to our laboratory for assessment of cutaneous fungal infection. Mycological examination consisted of culturing of pathological material followed by direct microscopy. Diagnosis was based on the macroscopic and microscopic characteristics of the colonies.
Results: Of the 3976 clinically suspected cases of dermatophytosis, 239 (39.6%) were zoophilic dermatophytosis, confirmed by direct examination and culture. They occurred in 93 (39%) female patients and 146 (61%) male patients (median age 27.4 years, range 1.5–75). The commonest zoophilic fungi isolated were Trichophyton mentagrophytes var. mentagrophytes (28%), followed by Trichophyton verrucosum (9.3%) and Microsporum canis (2.2%). The geophilic fungus Microsporum gypseum was isolated from 0.33% of patients.
Conclusion: This study identifies the epidemiological trends and the predominant organisms causing zoophilic dermatophytosis in humans in Tehran. Consideration of the current epidemiological trends in the incidence of cutaneous zoophilic fungal pathogens is essential for investigation, diagnosis and treatment.