The multi-parasite/multi-host system occurring at the wildlife ruminant community of Sierras de Cazorla, Segura y Las Villas National Park

Resumen

In this Doctoral Thesis, it has been studied the natural interaction that occurs on gastrointestinal and bronchopulmonary parasitic nematodes in four species of wild ruminants present in southeastern Spain. The phenomenon called multi-host (one nematode species shared by different hosts) and multi-parasitism (simultaneous infection with several parasitic species in the same host) was studied. In order to carry out this study, it has been chosen as study area the “Sierras de Cazorla, Segura and Las Villas Natural Park” (PNSCSV) in Andalucía (Spain), a location that allowed to evaluate naturally occurring multi-host/multi-parasite phenomenon. Studied hosts included two bovids (Iberian ibex [Capra pyrenaica]; European mouflon [Ovis orientalis musimon]) and two cervids (red deer [Cervus elaphus]; fallow deer [Dama dama]). The main objectives of this Doctoral Thesis are: • to describe the richness, prevalence, abundance and intensity of parasites, in a multi-parasite / multi-host context. • to discuss the epidemiological role and transmission of these parasites, trying to explain the parasite community from an ecological perspective. • to validate the larval migration technique or Baermann method by comparing parasite presence and load in lung and fecal samples of the same animals, using the Blant-Altman analysis. In Chapter 1 the gastrointestinal nematodes of the four wild ruminants species were studied from a multi-host point of view (n = 252 wild ruminants). Eighty-one point fifty-two of the animals analyzed were positive for parasitic infection and 29 species of nematodes were identified. Nematode prevalence differed significantly between host species (fallow deer, 91.5%; mouflon, 85.5%; Iberian ibex 83.3%;red deer, 61.4%). In addition, the mouflon presented the highest parasitic richness (12 different species). In this scenario, the structure of the parasite community was significantly influenced by the host, with the highest prevalence and richness of parasites consistently appearing in mouflon, suggesting a parasite dispersal point originated by the mouflon. The presence of significant differences between the 11 species of nematodes shared by all host species was shown. These findings highlight the ability of parasites to adapt to the host community and shape their distribution according to the host species available. Following the previously described line, in Chapter 2, the bronchopulmonary nematode community of the four wild ruminants species was studied. Almost half (48.0%) of the animals were infected with bronchopulmonary nematodes. Seven different nematodes were identified, of which two genera (Protostrongylus spp. and Dictyocaulus spp.) and three species (Cystocaulus ocreatus, Muellerius capillaris and Neostrongylus linearis) were recorded in at least two ruminants, being the mouflon the most affected host. From a spatial perspective, the highest abundance of parasites was detected in the central part of the study area. The mouflon was again the epidemiological key in the natural network of interactions, showing a high prevalence and richness of bronchopulmonary nematodes that are shared with other wild ruminant species. Chapter 3 describes the validation of the Baermann-Wetzel technique for the diagnostic of bronchopulmonary nematodes. This is the most common method for the diagnosis of bronchopulmonary nematodes, and it is based on the active migration and movement of their first stage larvae (L1). Lung tissue samples are frequently used for post mortem diagnosis of these parasites, to determine the parasitic infection status of a controlled wild population, but this type of sample is not always available. Faecal samples represent a non-invasive option for monitoring parasites, however, this type of sample is used mainly in domestic ruminants. The study showed a good level of sensitivity for the two simple types (86.7% for lung tissue and 84.1% in faeces). Hence, a good level of agreement, as well as a similar sensitivity, between the two types of samples, was observed, validating the use of faecal samples as a less invasive and cost-effective alternative for the follow-up of the infection with bronchopulmonary nematodes in wild ruminant populations. These results support the use and value of feces as a non-invasive and cost-effective sampling technique for long-term studies. The findings obtained throughout the three chapters that form this Doctoral Thesis provide valuable information allowing to better understand the natural multi-host and multi-parasitic system in the southeast of the Iberian Peninsula, highlighting the importance of each host species in the maintenance of the biological cycle of the nematodes