Invasive snails may drive fluke infection of African buffalo in Zimbabwe

Abstract

Parasite transmission and disease outcomes in wildlife are increasingly shaped by anthropogenic environmental change, yet empirical data linking parasites, intermediate hosts, and large mammal health remain scarce. Following an unusual mortality event involving wild ruminants in Imire Rhino & Wildlife Conservancy (Zimbabwe), we investigated the diversity, transmission, and potential health relevance of snail-borne trematodes within the buffalo-containing section of this human-modified landscape. To this end, we combined a post-mortem examination of an African buffalo (Syncerus caffer), standardized freshwater snail surveys, cercarial shedding experiments, xenomonitoring, and integrative morphological and molecular analyses. The buffalo was infected with Fasciola gigantica and an amphistome identified as Calicophoron aff. microbothrium. Snail surveys revealed four gastropod taxa, Physella acuta, Pseudosuccinea columella, Radix natalensis, and a Lentorbis-like Planorbidae species. The latter three species hosted trematode infections. Although no snails were found infected with F. gigantica, molecular screening linked C. aff. microbothrium infections in the buffalo to a naturally shedding P. columella, providing the first evidence that this invasive snail can act as a competent intermediate host for this amphistome. Additional trematodes detected in snails included Plagiorchis maculosus, Plagiorchis sp., Echinostoma sp., and a Plagiorchiida species. While trematode infections could not be directly implicated as the sole cause of mortality, their occurrence in a weakened buffalo and their association with invasive species highlight their potential role as an additional pressure under environmental stress. 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.