Gastro-intestinal nematode infections in four Alpine chamois herds: influence of host density on helminth egg output.

A three years survey on gastro-intestinal nematode egg output was carried out in four Alpine chamois herds (Rupicapra rupicapra rupicapra) from Belluno province (Italy). Data were analysed in order to detect the influence of cattle presence and chamois density on egg output, and to evaluate the stability of host-parasite relationship. As expected, variations related to the season were present, with the major peak of egg output observed in the summer. Results highlighted an unexpected inverse influence of host density on egg counts. The results are in relation to host-parasite relationship stability. Parasites seem to be able to self-regulate in the absence of parasite-induced host mortality. No effect due to cattle presence was detected.