title: Malaria relapses were already known before 1900-a discussion.
abstract: For a long time, only two phases of the life cycle of the agents of malaria parasites were known: the cycle inside the mosquito body and the cycle in the red blood cells of humans as intermediate hosts. A possible tissue development cycle inside humans, however, had already been proposed before 1900. In general, Pieter Klaesz Pel is considered the first scientist who has described such a tissue cycle. However, a closer look at Pel's work shows that he still followed an old (conservative) way of thinking, since he still referred to "malaria poison and malaria miasma." Thus, the first idea of a possible tissue cycle must be searched in the work of earlier scientists. Referring to their observations on malaria, Vassilij Danilevsky, Arman Ruffer, Camillo Golgi and Battista Grassi suspected developing parasites in internal organs, before they can be found in the bloodstream.
authors.affiliation: Institute for the History, Theory, and Ethics of Medicine, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany. gabriele.franken@uni-duesseldorf.de.
authors.forename: Gabriele
authors.identifier: http://orcid.org/0000-0002-1891-8675
authors.initials: G
authors.lastname: Franken
authors.affiliation: Institute for the History, Theory, and Ethics of Medicine, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Marita
authors.initials: M
authors.lastname: Bruijns-Pötschke
authors.affiliation: Institute of Tropical Medicine and International Public Health, Charité Universitätsmedizin, Berlin, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Richter
authors.affiliation: Institute for Zoomorphology, Cell Biology and Parasitology, Faculty of Biology, Heinrich- Heine-University, Düsseldorf, Germany.
authors.forename: Heinz
authors.initials: H
authors.lastname: Mehlhorn
authors.affiliation: Institute for the History, Theory, and Ethics of Medicine, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
authors.forename: Alfons
authors.initials: A
authors.lastname: Labisch
mesh_terms: D000818:Animals; D009033:Culicidae / Q000502:physiology; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D007303:Insect Vectors / Q000502:physiology; D008288:Malaria / Q000266:history* / Q000473:pathology / Q000635:transmission; D012008:Recurrence
keywords: Arman Ruffer; Camillo Golgi; Giovanni Battista Grassi; Malaria; Pieter Klaesz Pel; Relapse; Tissue cycle; Vassilij Danilevsky