Malaria relapses were already known before 1900-a discussion.

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.