Fecal parasite identification by microscopy and PCR in scimitar-horned oryx, Oryx dammah, managed at two sites

- Microscopy found Strongylus, Trichuris, Nematodirus, Eimeria, and Isospora at FRWC.
- Microscopy found Strongylus, Eimeria, and Isospora, at KCZ.
- The most commonly found helminth was from the genus Strongylus.
- Sequencing confirmed the presence of Strongylus, Trichuris, Eimeria, and Isospora.
- Both herds had lower FECs in comparison to wild ruminants in North America.

The scimitar-horned oryx, Oryx dammah, an endangered species extinct in the wild, is managed in various captive management programs and is the focus of reintroduction efforts. Management variability can contribute to substantial parasite load differences, which can affect deworming programs and potentially transfer parasites to different regions with translocations. Parasite studies in O. dammah are lacking. In this study, we determined fecal egg/oocyst counts of O. dammah in two captive herds, Fossil Rim Wildlife Center (FRWC) and Kansas City Zoo (KCZ). Fecal egg counts (FEC) were performed on O. dammah feces collected seasonally using the modified McMaster method, and microscopy provided additional identification of parasite genera ova and oocysts. To identify parasites to species level, homogenized fecals provided DNA subjected to the polymerase chain reaction (PCR) using genus specific primers. Microscopy and sequencing results indicated the presence of Strongylus (Strongylus vulgaris, Angiostrongylus cantonensis), Trichostrongylus (Haemonchus contortus, Camelostrongylus mentulatus), Trichuris (T. leporis, T. ovis, and T. discolor), Isospora (Isospora gryphoni) and Eimeria (E. zuernii and E. bovis), with Strongylus being the most common. Nematodirus was identified through microscopy at FRWC. Fecal egg counts were significantly higher in (FRWC) than in (KCZ) in all samplings (P = <0.001). No significant difference was seen between parasite load and seasons (P = 0.103), nor site and season (P = 0.51). Both study sites maintained most animals within commonly accepted FEC levels found in domestic livestock. Individuals with high numbers of EPG or OPG were subordinate males, pregnant females, or neonates. Several significant interactions were found between genera of parasites, age, sex, season, and pregnancy status in the FRWC herd. Sampling limitations prevented further analysis of the KCZ herd. Understanding interactions between parasite loads and physiological, environmental, and regional differences can help determine inter-specific transfer of parasites, and establish appropriate anthelmintic programs for O. dammah herds.

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