Invasive Pseudosuccinea columella enters the transmission cycle of an amphistome parasite infecting African buffalo

Abstract

Parasite transmission and disease outcomes in African wildlife are increasingly shaped by anthropogenic environmental change, yet empirical data linking parasites, intermediate hosts and wildlife health remain scarce. Following an unexplained increase in mortality among wild ruminants at a Zimbabwean conservancy, we investigated the diversity, transmission and potential health relevance of snail-borne trematodes within this managed wildlife conservancy. We combined a post-mortem examination of an African buffalo (Syncerus caffer), standardized freshwater snail surveys, cercarial shedding experiments, DNA-based screening in snails, and morphological and molecular analyses of snails and parasites. The buffalo was infected with the liver fluke Fasciola gigantica and an amphistome identified as Calicophoron aff. microbothrium. Snail surveys revealed 4 gastropod taxa: invasive Physella acuta and Pseudosuccinea columella, and native Radix natalensis and a Lentorbis-like planorbid. The latter 3 species hosted trematode infections. Molecular screening linked C. aff. microbothrium infections in the buffalo to a shedding P. columella, providing the first evidence that this invasive snail is a competent intermediate host for this amphistome. No snails were found infected with F. gigantica. Additional trematodes detected in snails included Plagiorchis maculosus, Plagiorchis sp., Echinostoma sp., and another species of the order Plagiorchiida. The presence of P. columella as a competent intermediate host, combined with its known role in Fasciola transmission in Africa, highlights the potential for parasite spillback and elevated disease transmission. Our findings underscore the value of integrated approaches and emphasize persistent taxonomic and ecological knowledge gaps that limit understanding of trematode-driven disease dynamics in African wildlife.