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Host effects on the free-living stages of Haemonchus contortus

A group of 5 lambs (Host 1–5) was infected with the same batch of Haemonchus contortus and after patency individual faecal samples were collected, separately incubated at 23 °C for 14 days and third stage larvae collected through Baermannisation. Life-history traits were compared between larvae from different hosts: the length of the larvae was measured by microscope image analysis, larval survival in water at 35 °C, larval susceptibility to ivermectin (EC50) in a migration assay, the proportion of larvae exsheathing in vitro and the proportion establishing to the adult stage in young lambs. For all traits there were significant differences between the host animals, with larvae from specific hosts following a consistent pattern of displaying the highest or lowest trait results. Compared with larvae from Host 1 the larvae from Host 5 were () shorter (741–692 μm, p < 0.05), had a longer median survival at 35 °C (3.6–6.4 days, p < 0.05), were less susceptible to ivermectin (EC50 of 1.2 v 4.5 μM, p < 0.05), exsheathed to a lesser degree (83.6–58 %, p < 0.05), but showed a higher establishment rate in the consecutive host (15.2–31.4 %, p < 0.05). Regarding the survival time, anthelmintic susceptibility (under most commercial farming practices) and establishment rate as indicators for fitness, the parasites populating Host 5 produced progeny of higher fitness. The findings indicate that the host animal of the parental parasite generation has a significant effect on the parasite progeny.

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Rights statement

© 2021 Elsevier Ltd. All rights reserved.

Language

  • English

Does this contain Māori information or data?

  • No

Publisher

Elsevier

Journal title

Veterinary Parasitology

ISSN

0304-4017

Citation

Sauermann, C. W, Candy, P., Waghorn, T. S., Bekelaar, K., & Leathwick, D. M. (2021). Host effects on the free-living stages of Haemonchus contortus. Veterinary Parasitology, 292, 109401. doi:10.1016/j.vetpar.2021.109401

Job code

PRJ0155815

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