outbreak did not lie in individual treatment or by providing small changes in housing, food or clothing, but rather in widespread structural changes to directly address the issue of poverty. Virchow's experience in Upper Silesia led to his observation that "Medicine is a social science". His report led to changes in German public health policy. 20th century Typhus was endemic in Poland and several neighboring countries prior to World War I (1914–1918). During and shortly after the war, epidemic typhus caused up to three million deaths in Russia, and several million citizens also died in Poland and Romania. Since 1914, many troops, prisoners and even doctors were infected, and at least 150,000 died from typhus in Serbia, 50,000 of whom were prisoners. Delousing stations were established for troops on the Western Front, but the disease ravaged the armies of the Eastern Front. Fatalities were generally between 10 and 40 percent of those infected, and the disease was a major cause of death for those nursing the sick. During World War I and the Russian Civil War between the White and Red, the typhus epidemic caused 2–3 million deaths out of 20–30 million cases in Russia between 1918 and 1922. 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, Dachau, 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. Following the development of a vaccine during World War II, Western Europe and North America have been able to prevent epidemics. These have usually occurred in Eastern Europe, the Middle East, and parts of Africa, particularly Ethiopia. Naval Medical Research Unit Five worked there with the government on research to attempt to eradicate the disease. In one of its first major outbreaks since World War II, epidemic typhus reemerged in 1995 in a jail in N'Gozi, Burundi. This outbreak followed the start