Helmintofauna del visón americano (Neovison vison), el lobo ibérico (Canis lupus signatus) y el zorro (Vulpes vulpes) en el noroeste de la Península Ibérica

Résumé

In this PhD thesis, the helminthfauna of three wild carnivore species present in northwestern Spain -the American mink (Neovison vison), an allochthonous mustelid, the fox (Vulpes vulpes) and the Iberian wolf (Canis lupus signatus), both native canid species- has been studied. Currently, the populations of these three carnivores are expanding, despite the hunting pressure and the control measures to which they are subjected. The approximation of wild fauna to anthropized areas entails a greater contact, either direct or indirect, between domestic and wild animals, as well as with humans, increasing the epidemiological risk of pathogen transmission in the domestic-will-human interface. The study was based on the necropsy of 50 American minks, 257 foxes and 83 wolves. The thoracic and abdominal viscera were dissected, washed and their contents filtered and subsequently examined under the stereomicroscope. In addition, the lung parenchyma was digested with pepsin and hydrochloric acid to facilitate the extraction of helminths. All the parasites were recovered, washed and preserved in 70% ethanol until identification. In addition, a portion of 94 wolf cestodes was preserved in absolute ethanol for specific identification by PCR. The digestive and cardiopulmonary nematodes were clarified with lactophenol, while wolf and fox cestodes, as well as American mink trematodes, were stained with Semichon’s acetic carmine for further identified using morphometric keys. In Chapter 1 we have described the gastrointestinal and cardiopulmonary helminths from the American mink in Galicia in order to evaluate the role of this mustelid as a reservoir and disseminator of parasites introduced simultaneously with this invasive species, or if this host has been incorporated to the sylvatic life cycle of helminths of autochthonous mustelids and other wild carnivores of the colonized area. Eight species of parasites (six nematodes and two trematodes) were found: Molineus patens, Aonchotheca putorii, Crenosoma melesi, Aonchotheca annulosa, Angiostrongylus daskalovi, Aelurostrongylus spp., Troglotrema acutum and a digestive trematode which could not be identified. All these species are native to European mustelids. This is the first report of A. daskalovi and A. annulosa in the American mink. and the first record of the trematode T. acutum in the lung, an ectopic location. In Chapter 2 we have described the cardiopulmonary nematode species present in Iberian wolves and foxes from Galicia and Asturias, discussing their epidemiological role in the natural nesting and dispersal of these parasites, which also affect the dog, inducing an important pathogenic action in the host. Four nematode species were identified: Angiostrongylus vasorum, Eucoleus aerophilus, Crenosoma vulpis and Filaroides hirthi. Both carnivores shared the same nematode species, except F. hirthi, which was only found in wolves, being the first report of this nematode in this canine worldwide. The different prevalence of these parasites in foxes and wolves is probably related to disparities in their respective trophic behavior. Based on our results, we hypothesized that cardiopulmonary nematodes have co-evolved with their respective definitive, intermediate and paratenic hosts, thus foxes have become the hosts with the highest prevalence and parasite intensity when compared to wolves. This could be considered as an adaptation of this top predator based on a trophic strategy which reduces their risk of infection. In Chapter 3 we have studied the gastrointestinal helminthfauna of foxes and Iberian wolves in the northwest of the Iberian Peninsula, analyzing their epidemiological role in the maintenance and transmission of these parasites, highly important from a sanitary point of view, since many of their pathogens can also affect domestic animals or even humans. A total of 13 helminth species (five nematodes and eight cestodes) were detected. The nematodes Uncinaria stenocephala, Toxocara canis, Trichuris vulpis, and the cestodes Taenia hydatigena, Taenia pisiformis, Taenia crassiceps, Mesocestoides spp. and Dipylidium caninum were identified in both wild canines, while Ancylostoma caninum and Taenia krabbei were only isolated in wolves, being the first description of this cestode in the Iberian Peninsula. Finally, Toxascaris leonina, Taenia polyacantha and Taenia taeniaeformis were found exclusively in foxes. In addition, the presence of cestodes T. hydatigena and T. krabbei were confirmed by PCR. Foxes showed a helminthfauna typically associated to carnivores which consume small prey, such as rodents. On the opposite wolves were mainly infected with parasites transmitted by the ingestion of large prey, such as ungulates. In this way, it is evident that the ecological particularities, mainly the trophic ones, of the host species are decisive for the gastrointestinal helminthfauna of each wild canid, and therefore, also determine their epidemiological role in the maintenance of the biological cycle and dispersion of these parasites.