Epidemiology: a retrospective study.
D002487:Centers for Disease Control and Prevention, U.S.; D002771:Cholera / Q000517:prevention & control; D004813:Epidemiology / Q000266:history*; D005602:France; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D011635:Public Health Administration / Q000266:history; D012189:Retrospective Studies; D012499:Sanitation / Q000517:prevention & control; D012899:Smallpox / Q000517:prevention & control; D014435:Typhoid Fever / Q000517:prevention & control; D006113:United Kingdom; D014481:United States