Sources: Various, including BBC News, Centers for Disease Control and Prevention, Joint United Nations Programme on HIV/AIDS, National Center for Biotechnology Information, New World Encyclopedia, Nigeria Centre for Disease Control, The British Medical Journal, The Free Press Journal, The Lancet, World Health Organization. Notes: Outbreaks have been included if they meet the following criteria: resulted in more than 100 deaths; geographically widespread, ie a pandemic or a major epidemic within a country. It has not been possible to show all outbreaks that meet the criteria as not all death tolls could be confirmed, eg for the sixth and seventh cholera pandemics. For the purposes of this visualisation, all HIV/AIDS cases since 1981 have been considered as part of one sustained epidemic. Data as of 25 August 2021.