Nation-wide analysis of prevalence and proliferation factors of the zoonotic dermatophyte Trichophyton benhamiae in Germany
For about 10 years, a new variant of the pathogen Trichophyton (T.) benhamiae has been appearing in Germany, characterised by a previously unobserved culture phenotype with a strong yellow reverse. A few studies suggest that this new variety is now the most common zoophilic dermatophyte in Germany. Guinea pigs are the main carrier. Exact prevalence measurements are not yet available. Thus, the aim of the present study was to collect data on the frequency and geographic distribution of the pathogen and its phenotypes (white and yellow) in humans and guinea pigs throughout Germany. Studies have already shown that animals from large breeding farms are affected particularly heavily. In contrast to this, 21 small private breeds were sampled and husbandry conditions recorded. This enabled us to identify propagation factors and to give recommendations for containment. For animals from private breeds, we detected T. benhamiae with a prevalence of 55.4%, which is less than half compared to animals from large breeding farms. As risk factors, we identified the type of husbandry and the contact to other breeds. Furthermore, certain breeds, like Rex guinea pigs and breeds with long curly hair were predestined for colonisation by T. benhamiae due to their phenotypic coat characteristics. A prevalence of 36.2% was determined for symptomatic pet guinea pigs suspected of having dermatophytosis, which is comparable to the study by Kraemer et al., showing a prevalence of 34.9% in 2009 in Germany. The prevalence in humans is stable with about 2–3%, comparing data of 2010–2013 and 2018 in Thuringia. The new type of T. benhamiae was by far the most frequent cause in all settings.