A case-control analysis and laboratory study of the two feet-one hand syndrome in two dermatology hospitals in China.

Summary Background.  Two feet–one hand syndrome (bilateral plantar tinea pedis with coexistent unilateral tinea manuum) is commonly seen in dermatology clinics, but the cause of the unilateral hand involvement remains unresolved. Aims.  To investigate the unilateral hand involvement in this syndrome. Methods.  This was a case–control study. The experimental group comprised 113 patients with bilateral tinea pedis and unilateral tinea manuum and the control group comprised 44 patients with tinea pedis only, without tinea manuum. Clinical data were recorded and pathogens were identified by fungal examination. The predominant pathogen, Trichophyton rubrum, was genotyped by PCR amplification of tandem repeat elements from the ribosomal DNA nontranscribed spacer region. Results.  Scratching habits were significantly different between the groups, and there was a significant relationship between tinea manuum and the hand reportedly used to scratch the feet. In analysis of isolates from the feet and the involved hand, 94.5% of pairs were of the same species, and 80% of pairs had the same genotypes. Conclusions.  Contact between hands and feet probably results in the transmission of dermatophytes from the feet to the scratching hand.