Typhus caused hundreds of thousands of deaths during World War II. It struck the German Army during Operation Barbarossa, the invasion of Russia, in 1941. In 1942 and 1943 typhus hit French North Africa, Egypt and Iran particularly hard. Typhus epidemics killed inmates in the Nazi concentration camps and death camps such as Auschwitz, Theresienstadt, and Bergen-Belsen. Footage shot at Bergen-Belsen concentration camp shows the mass graves for typhus victims. Anne Frank, at age 15, and her sister Margot both died of typhus in the camps. Even larger epidemics in the post-war chaos of Europe were averted only by the widespread use of the newly discovered DDT to kill lice on the millions of refugees and displaced persons.