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Australian Journal of Zoology Australian Journal of Zoology Society
Evolutionary, molecular and comparative zoology
RESEARCH ARTICLE

Temporal dynamics of helminth infections in eastern grey kangaroos (Macropus giganteus) in Victoria

Jemma Cripps A B C , Ian Beveridge B , Jennifer K. Martin A , Duncan Borland B and Graeme Coulson A
+ Author Affiliations
- Author Affiliations

A School of BioSciences, The University of Melbourne, Melbourne, Vic. 3010, Australia.

B Faculty of Veterinary Science, The University of Melbourne, Veterinary Clinical Centre, Werribee, Vic. 3030, Australia.

C Corresponding author. Email: crippsj@unimelb.edu.au

Australian Journal of Zoology 63(3) 163-174 https://doi.org/10.1071/ZO15003
Submitted: 6 January 2015  Accepted: 1 June 2015   Published: 16 July 2015

Abstract

Parasite infection is increasingly recognised as a factor shaping the population dynamics, life history and behaviour of hosts. However, before the impacts of parasites on wildlife hosts can be investigated, seasonal patterns in host exposure to parasitic agents must be determined. We examined infection patterns at three sites in Victoria, and combined field experiments and observations to construct a generalised life cycle of the helminth community in eastern grey kangaroos (Macropus giganteus). Kangaroo populations in Victoria had very similar helminth communities, with 20–25 species detected at each site. Despite examining relatively few hosts in this study, at least 87% of all gastrointestinal helminths were recovered according to bootstrap estimates. The prepatent period of infection in eastern grey kangaroo nematodes was at least 3 months, and faecal egg output showed a distinct seasonal pattern, with a peak in egg counts from October through to January each year. Data from one site indicated that faecal egg counts were influenced predominantly by the abundance of a single nematode species (Pharyngostrongylus kappa), despite adults accounting for only 7% of the total nematode burden. This highlights the problems associated with using faecal egg counts to estimate nematode burdens in this host. Contamination of pasture plots showed that nematode eggs take ~14 days to larvate once deposited, and that autumn rains likely triggered emergence from faecal pellets. The abundance of infective larvae in the environment therefore appears to be closely tied to environmental conditions, with a peak in infection of hosts in the winter months.

Additional keywords: faecal egg count, infection patterns, Macropodidae, parasites.


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