Determinants of regional differences in the incidence of impetigo

Background and objectiveImpetigo is a common contagious skin infection, mostly seen in children and caused by Staphylococcus aureus and/or group A B-hemolytic Streptococcus. Two surveys performed in general practice showed a strong geographical gradient in the incidence rates among children in the Netherlands. The incidence in the south was approximately twice as high as in the rest of the Netherlands. We hypothesized that this difference could be explained by differences in the presence of animal farms and differences in temperature. This study examined whether there is a relationship with the numbers of bovines, pigs, sheep, and poultry per km2, and temperature, which could explain the observed regional gradient in the incidence of impetigo.Design and settingIn this ecological study, data on the incidence of impetigo in children 0–17 years of age from the second Dutch national survey were linked to data on the density of farm animals from Statistics Netherlands and temperature data from the Dutch Metereological Service. Using logistic regression allowing for overdispersion, we tested the significance of the effect of bovines, pigs, sheep, and poultry per km2, and temperature on the incidence of impetigo, correcting for known risk factors.ResultsOnly the number of sheep at the (COROP) regional level was significant; however, this effect could not explain the regional differences.ConclusionThe regional differences in the incidence of impetigo in children cannot be explained by the variation in the presence of farm animals or differences in temperature.