A comparison of the intestinal helminth communities of Equidae in Southern Africa.

The intestinal helminth communities of 8 horses, 12 donkeys, 21 Hartmann's mountain zebras, and 44 Burchell's zebras were compared using the original data from 6 studies in South Africa and Namibia. Necropsy and worm recovery techniques were comparable between the studies. Sixty helminth species (58 nematode, 1 cestode, and 1 trematode species) were recorded. There were significant differences in the helminth community structures of the 4 Equus species. The helminth communities of the 2 closely related zebra subspecies were most similar, and they jointly shared 7 helminth species with donkeys and only 1 with horses. Geographic variation and host-mixing contributed to the helminth species composition. Multiple confamilial species infections were the norm in the donkeys and zebra subspecies, and no single-species infection was recorded for the Strongylidae. Congeneric species were commonly recorded in 3 genera (Cyathostomum, Cylicocyclus, and Cylicostephanus). The shape of the occupancy frequency distributions for the donkeys and zebra subspecies was multimodal, with no clear satellite or core modes. Despite the presence of environmental variability and comparatively low parasite-host specificity, the phylogenetic signal within Equus helminth communities remains strong.