[Epidemiology of Behçet's disease]

With more than 30 published prevalence estimates for Behçet's disease (BD), covering many different regions worldwide, the prevalence of BD is quite well described. Even though the interpretation of these data is complicated by between-study differences in methodology, which may substantially influence the results, these data suggest large geographic variations in frequency of BD, with prevalence rates of 20-420/100,000 inhabitants for Turkey, 2.1-19.5 for other Asian countries, 1.5-15.9 for southern Europe and 0.3-4.9 for northern Europe. Additional epidemiological studies or case series from North and South America, the Caribbean Islands, and individuals of sub-Saharan ancestry further suggest that the geographic distribution of BD is much wider than the boundaries of the ancient Silk Road. The few available incidence rates prevent from making strong inferences as to whether the frequency of BD has changed over time. Recent population-based studies of immigrants or migrant populations consistently indicate that migrants from areas of high BD prevalence remain at high risk for BD, which may even be close to the prevalence observed in their countries of origin. Genetic factors, which are not detailed in this review, seem to play a preponderant role in BD development, although they cannot explain the wide between-country disparities in BD prevalence. However, environmental risk factors, including infectious and non-infectious causes, remain poorly investigated and have not yet produced solid hints.