Trichophyton mentagrophytes of rabbit origin causing family incidence of kerion: an environmental study

Our laboratory was contacted by a family living directly above a rabbit farm. Both their children had developed a kerion, in consequence of a misdiagnosed superficial mycosis. This study was designed to demonstrate a link between the two kerion cases and the environmental contamination. The degree of contamination was estimated and factors favourising the spread of infection were determined. Dermatophytes were isolated from various environmental sites using Rodac plates. For direct sampling of scalp and fur the brushing technique was used. The farm and home environment initially showed a severe contamination by Trichophyton mentagrophytes. At the farm, cages and surfaces covered with rabbit hair were strongly contaminated. As for the home environment, the dog's basket and clothes from the mother carried a large number of spores. Trichophyton mentagrophytes was identified as responsible agent for the children's kerions and the lesions of the rabbits. Mother, eldest child and dog seemed to be excellent carriers. Cleaning and disinfection measures resulted in a reduction of the overall contamination. The home environment was no longer a source of contamination. Nevertheless, on the farm a fair number of dermatophytes could still be isolated from the wire meshes and roof beams covered with fluff.