Onychomadesis outbreak linked to hand, foot, and mouth disease, Spain, July 2008.

In July 2008 an onychomadesis outbreak in a nursery setting was reported in Saragossa (Spain). Some of the cases had previously suffered from hand, foot and mouth disease (HFMD). In order to study the outbreak and to determine the relation between the two diseases, two epidemiological studies were conducted: a descriptive study focused on cases and a retrospective cohort study. Samples from stool, pharynx and nails were obtained from cases for microbiological analysis. During the study period, 27 children fulfilled the case definition. The average age was 1.8 years. A case shed on average four nails (minimum one maximum twelve). Twenty-four of the 27 cases had previously presented with HFMD which started an average of 40 days before the onset of onychomadesis (relative risk: 14). Unidentified non-polio enterovirus (n=10), coxsackie B1 (n=4) and coxsackie B2 virus (n=3) were isolated in 28 specimens obtained from 14 cases. The analysis showed a strong association between HMFD and onychomadesis. Microbiological results have not been conclusive; consequently more studies are necessary to determine the causal agent of infectious onychomadesis.