Abstract Although large and small piroplasms have been reported from various wild carnivore and ungulate species, relatively few have been named. In the past, mere presence of a piroplasm in a specific host frequently prompted naming of a new species. Descriptions were often inadequate or lacking altogether. Currently, demarcation of species relies heavily on molecular characterisation. Even serological evidence is deemed insufficient. Experimental transmission of Babesia spp. from domestic to wild animals is usually only successful in closely related species, or after splenectomy. There are indications that endemic stability, similar to the situation in livestock, is the general pattern in Babesia sp. infections in wildlife. All lions in Kruger National Park were found to be infected with B. leo, which did not lead to clinical disease manifestation in artificially infected lions. Under stressful conditions, infections could flare up and be fatal, as purportedly happened to the famous lioness ''Elsa''. Similarly black rhinos, which can harbour Babesia bicornis without ill effects, may develop clinical babesiosis during confinement after capture. Zoo-bred animals, which were not exposed to Babesia spp. at a young age, may be fully susceptible when released into a natural environment where other members of their species occur. This could have major implications for ex situ conservation programmes aimed at bolstering natural wildlife populations.
