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Selected Publication:

Type of publication: Journal Article
Type of document: Full Paper

Year: 2006

Authors: Hoby, S; Schwarzenberger, F; Doherr, MG; Robert, N; Walzer, C

Title: Steroid hormone related male biased parasitism in chamois, Rupicapra rupicapra rupicapra.

Source: Vet Parasitol. 2006; 138(3-4):337-348

Authors Vetmeduni Vienna:

Schwarzenberger Franz
Walzer Christian

Vetmed Research Units
Institute for Medical Biochemistry
Research Institute of Wildlife Ecology

Project(s): Energetics of chamois and human disturbance impact

Parasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host"s immune response to the structuring of communities and the evolution of biodiversity. As in many species sex determines life history strategy, response to parasites may be sex-specific. Males of vertebrate species tend to exhibit higher rates of parasites than females. Sex-associated hormones may influence immunocompetence and are hypothesised to lead to this bias. In a field study, we tested the prediction of male biased parasitism (MBP) in free ranging chamois (Rupicapra rupicapra rupicapra), which are infested intensely by gastrointestinal and lung helminths. We further investigated sex differences in faecal androgen (testosterone and epiandrosterone), cortisol and oestrogen metabolites using enzyme immunoassays (EIA) to evaluate the impact of these hormones on sex dependent parasite susceptibility. Non-invasive methods were used and the study was conducted throughout a year to detect seasonal patterns. Hormone levels and parasite counts varied significantly throughout the year. Male chamois had a higher output of gastrointestinal eggs and lungworm larvae when compared to females. The hypothesis of MBP originating in sex related hormone levels was confirmed for the elevated output of lungworm larvae, but not for the gastrointestinal nematodes. The faecal output of lungworm larvae was significantly correlated with androgen and cortisol metabolite levels. Our study shows that sex differences in steroid levels play an important role to explain MBP, although they alone cannot fully explain the phenomenon.

Keywords Pubmed: Analysis of Variance
Gonadal Steroid Hormones/physiology*
Helminthiasis, Animal/classification
Helminthiasis, Animal/epidemiology
Helminthiasis, Animal/parasitology*
Host-Parasite Interactions/physiology
Nematoda/isolation & purification
Parasite Egg Count/veterinary
Platyhelminths/isolation & purification
Poisson Distribution
Sex Factors

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