common ancestor of all known human HBV strains was dated to between 20,000 and 12,000 years ago, pointing to a more recent origin for all HBV genotypes. The evolution of HBV in humans was shown to reflect known events of human history such as the first peopling of the Americas during the late Pleistocene and the Neolithic transition in Europe. Ancient DNA studies have also showed that some ancient hepatitis viral strains still infect humans, while other strains became extinct. The earliest record of an epidemic caused by virus was made by Lurman in 1885. An outbreak of smallpox occurred in Bremen in 1883 and 1,289 shipyard employees were vaccinated with lymph from other people. After several weeks, and up to eight months later, 191 of the vaccinated workers became ill with jaundice and were diagnosed with serum hepatitis. Other employees who had been inoculated with different batches of lymph remained healthy. Lurman's paper, now regarded as a classical example of an epidemiological study, proved that contaminated lymph was the source of the outbreak. Later, numerous similar outbreaks were reported following the introduction, in 1909, of hypodermic needles that were used, and, more importantly, reused, for administering Salvarsan for the treatment of syphilis. The largest outbreak of Hepatitis B ever recorded was the infection of up to 330,000 American soldiers during World War II. The outbreak has been blamed on a yellow fever vaccine made with contaminated human blood serum, and after receiving the vaccinations about 50,000 soldiers developed jaundice. The virus was not discovered until 1966 when Baruch Blumberg, then working at the National Institutes of Health (NIH), discovered the Australia antigen (later known to be surface antigen, or HBsAg) in the blood of Aboriginal Australian people. Although a virus had been suspected since the research published by Frederick MacCallum in 1947, David Dane and others discovered the virus particle in 1970 by electron microscopy. In 1971, the FDA issued its first-ever blood supply screening order to blood banks. By the early 1980s the genome of the virus had been sequenced, and the first vaccines were being tested. Society and culture World Hepatitis Day, observed 28 July, aims to raise global awareness of and hepatitis C and encourage prevention, diagnosis, and treatment. It has been led by the World Hepatitis Alliance since 2007 and in May 2010, it received global endorsement from the World Health Organization. See also Infectious