born June 24, 1852, Frankfurt an der Oder, Prussia
died April 9, 1915, Berlin, Ger.
German bacteriologist.
In 1884, with Edwin Klebs (18341913), he discovered the organism that causes diphtheria . Simultaneously with Émile Roux (18531933) and Alexandre Yersin (18631943), he indicated the existence of a diphtheria toxin. His demonstration that some animals are immune to diphtheria was basic to Emil von Behring's work in developing antitoxins. Löffler also discovered the cause of some swine diseases and identified, with Wilhelm Schütz, the organism that causes the horse disease glanders. With Paul Frosch he found that foot-and-mouth disease is caused by a virus (the first time a virus was found to be the agent of an animal disease) and developed a serum against it.