Commentary: Kristian Feyer Andvord's studies on the epidemiology of tuberculosis and the origin of generation cohort analysis

Accepted 3 April 2008The Norwegian physician Kristian Feyer Andvord(1855–1934) who had no training in epidemiology,observed differences in mortality rates from tuber-culosis between counties in Norway late 19th centuryand started in the 1890s to speculate on why the ratesdiffered between counties and had fallen for infantsbut not adults. This triggered him to spend his careeron the natural history of tuberculosis by means ofpopulation data and made him suggest that primaryinfection with tuberculosis mainly takes place inchildhood and that falling mortality rates at thetime of observation was a reflection of exposure earlyin life.