[Reinfection and recidive in Hymenolepis nana infections (author's transl)].

The excretion of Hymenolepis nana eggs begins in CF-1 mice between the 11th and 12th day irrespective of the wormload. In Swiss mice, however, the onset of egg excretion can be retarded up to the 15th day if the number of parasites is high. The re-appearance of eggs after treatment occurs between the 6th and 9th day using an exact diagnostic method. If the number of parasites is low, than re-appearance of eggs occurs later than if it is high. An infection with eggs protects mice for several months against a re-infection with eggs but not against one with cysticercoids. If cysticercoids are used to establish the primary infection no immune reaction against a re-infection develops. If eggs reappear in the faeces after treatment then the following conclusion can be drawn: Eggs reappear within a week after treatment then it must be a relapse. Eggs reappear during the second week then it can be either a relapse or a re-infection. Eggs reappear at three weeks or later then it can only be due to a re-infection.