A survey of gastrointestinal nematode species in red deer (Cervus elaphus) farms in New Zealand using PCR

Inconsistency of in vitro exsheathment triggers for gastrointestinal nematode parasites of sheep, cattle and deer

Exsheathment is crucial in the transition from free-living to parasitic phase for most strongyle nematode species. A greater understanding of this process could help in developing new parasitic control methods. This study aimed to identify commonalities in response to exsheathment triggers (heat acclimation, CO2 and pH) in a wide range of species (Haemonchus contortus, Trichostrongylus spp., Cooperia spp., Oesophagostomum spp., Chabertia ovina, and members of the subfamily Ostertagiinae) from sheep, cattle and farmed deer. The initial expectation of similarity in pH requirements amongst species residing within the same organ was not supported, with unexpected pH preferences for exsheathment of Trichostrongylus axei, Trichostrongylus vitrinus, Trichostrongylus colubriformis and Cooperia oncophora. We also found differences between species in their response to temperature acclimation, with higher exsheathment in response to heat shock observed for H. contortus, Ostertagia ostertagi, T. axei, T. vitrinus and Oesophagostomum sikae. Furthermore, some species showed poor exsheathment under all experimental conditions, such as Cooperia curticei and the large intestinal nematodes C. ovina and Oesophagostomum venulosum. Interestingly, there were some significant differences in response depending on the host from which the parasites were derived. The host species significantly impacted on the exsheathment response for H. contortus, Teladorsagia circumcincta, T. vitrinus and T. colubriformis. Overall, the data showed variability between nematode species in their response to these in vitro exsheathment triggers, highlighting the complexity of finding a common set of conditions for all species in order to develop a control method based on triggering the exsheathment process prematurely.

Diversity and burden of helminthiasis in wild ruminants in Iran

This paper aimed to investigate the diversity and burden of helminthiasis in Ovis orientalis (n = 26), Capra aegagrus (n = 29) and Gazella subgutturosa (n = 24) grazed in 37 National Parks in 9 provinces of Iran. The organs and body cavities infected by helminths included gastrointestinal tract, peritoneal cavity, heart, liver and lungs. The contents were extracted and washed under running water and intestinal and lung-isolated nematodes were cleared in lactophenol and subsequently fixed, and cestodes were stained with alum carmine and mounted en face in Berlese's fluid under slight pressure between a microscopic slide and cover slip. The helminth species identified in this study include: intestinal nematodes (Marshallagia marshalli, Teladorsagia circumcincta, Ostertagia ostertagi, Nematodirus oiratianus, Nematodirella longispiculata, Skrjabinema ovis, Trichuris ovis, Trichuris discolor, Parabronema skrjabini), lungworms (Protostrongylus rufescens, Cystocaulus ocreatus), adult cestodes (Moniezia expansa, Helicometra giardi, Avitellina centripunctata, Stilesia globipunctata) and metacestodes (Cysticercus spp., hydatid cyst, Cysticercus tenuicollis). The proportion of the different helminth species ranged from low to moderate (3.45-46.15%) and the intensity of helminth isolation from the different ruminants ranged between 2 and 20. All the taxa identified in our study have been reported in wild animal species around the world. The presence of Cysticercus spp. with cardiac involvement in G. subgutturosa and all helminths of C. aegagrus was reported for the first time in Iran. A significant reduction was observed in worm burden, compared with previous studies in Iran, indicating changes in wildlife host-parasite systems, which can be linked to many reasons including climate changes, public health policies (e.g., strategic anthelmintic use in domestic ruminants), anthropogenic factors and environmental changes (e.g., urbanization or agricultural expansion, physical barriers), as well as vegetation growth and host availability.