Missing links in the genesis of type 1 diabetes : A geographical approach to the case of enteroviruses in the Nordic region

Abstract: Type 1 diabetes (T1D) is an autoimmune disease that destroys the bodies’ insulin producing beta-cells. The disease is understood to be triggered in genetically susceptible individuals by environmental factors. While the genetic side of the etiological model has to some degree been uncovered, there is no clear understanding of which environmental factors play a role in the disease process. Several hypotheses claim to explain the development of T1D, of which enteroviral infections show the most promise. According to this hypothesis high prevalence of enteroviral infections would also mean high incidence rates of T1D. This study focused on four Nordic countries (Denmark, Finland, Norway and Sweden) that as late as 2017 were found in the top 10 countries for incidence rate of childhood-onset T1D in the world. Incidence rates of T1D and prevalence of enteroviruses were mapped and geographically analyzed according to the principles of spatial epidemiology, after which correlation coefficients were calculated. In doing so the study tried to answer to which extent the prevalence of enteroviruses could explain the regional variations in T1D. For all countries no significant correlation was found, but increasing sample size, by grouping countries, showed considerably different outcomes with a small positive correlation in the case of Norway and Finland.