The typical cestodes of the red fox in eastern areas of the Iberian Peninsula have a grouped distribution.

The red fox (Vulpes vulpes) is the most abundant wild canid in the Iberian Peninsula, and can act as a carrier of a wide range of parasite species shared with dogs and cats and which are sometimes zoonoses. Despite this, few studies are available describing the distribution and epidemiology of the cestode community of this opportunistic carnivore in areas of Mediterranean climate. In this study, prevalence, intensity, abundance and aggregation coefficient of cestodes found in 286 red foxes of the Valencian Community (East Spain) were calculated. For the most prevalent species, presence data were combined with environmental variables in order to build spatial models and predict the limiting factors associated with the decrease of suitable habitat for these parasites. The overall prevalence of cestodes was 83.22 % (238/286). Specifically, foxes harboured Mesocestoides spp. (75.87 %), Joyeuxiella echinorhynchoides (27.62 %), Taenia pisiformis (13.29 %), Dypilidium caninum (3.15 %), Taenia polyacantha (1.05 %), Taenia hydatigena (0.70 %), Taenia crassiceps (0.70 %) and Taenia spp. (0.35 %). Tetrathyridia larvae were found both in thoracic and abdominal cavity of three foxes (1.05 %), being the first time that this metacestode stage is described in the thoracic cavity of the red fox. Models on Mesocestoides spp. (Area Under the Curve, AUC = 0.80) and J. echinorhynchoides (AUC = 0.83) indicate that anthropogenic, climatic and environmental factors efficiently describe the habitat shape of parasites. This study emphasizes that foxes in Mediterranean areas are hosts of cestodes of veterinary and public health concern. Furthermore, our results demonstrate the usefulness of Ecological Niche Modeling applications for mapping the distribution of fox parasites and identifying areas of higher epidemiological risk for this wild canid, as well as for dogs and cats and, in the case of Mesocestoides spp., for humans.

First epidemiological data on Spirocerca vulpis in the red fox: A parasite of clustered geographical distribution.

This is the first study describing the epidemiology of Spirocerca vulpis after its description as a new species in 2018. During the period 2006-2013, a total of 286 red foxes (Vulpes vulpes) from the Valencian Community (southeast Spain) were necropsied. Based on data collected, S. vulpis prevalence and intensity were calculated, as well as the spatial distribution of this nematode. Influence of host (sex and age) and environmental factors on S. vulpis occurrence was evaluated. MAXENT software was used to model and predict the parasite distribution. Continuous and discrete prediction maps were built using ArcMap 10.6. The prevalence of S. vulpis was 22% (63/286; 95% CI: 17.4-27.3), and the median intensity was 5 (IQR 11) nematode specimens. No significant difference in term of intensity was found between males and females; regarding the host age, S. vulpis was found only in adult foxes, with the exception of one juvenile individual. The distribution of S. vulpis in foxes was skewed to the left, highlighting that parasite infection affects few individuals within a population, with parasitized animals being responsible to maintain the infection at the population level. The majority of parasitized foxes had a parasite burden lower than eight parasites/individual. S. vulpis distribution in Valencian Community presents sharply defined areas in which there are optimal environmental conditions for maintaining the life cycle of this parasite. Climatic variables and altitude are the main factors influencing the parasite presence. Our results indicate that S. vulpis has epidemiological characteristics similar to those of S. lupi and, therefore, based on the phylogenetic proximity of both nematode species, it is likely that coprophagous beetle species might play a key epidemiological role in the maintenance of this newly described Spirocerca species. Moreover, it is currently unknown if S. vulpis can infect the dog and other wild canid species apart from the red fox and, if so, what are the pathogenic effects on these host species. Therefore, it is necessary to continue investigating the epidemiology of this parasite in order to know the range of appropriate host species. This information will enable to know if S. vulpis endemic areas should be considered as health risk points for dogs, especially for the most exposed, such as those living in rural areas, and hunting dogs.

Spirocerca vulpis sp. nov. (Spiruridae: Spirocercidae): description of a new nematode species of the red fox, Vulpes vulpes (Carnivora: Canidae).

Previous studies have reported nematodes of the Spirocercidae family in the stomach nodules of red foxes (Vulpes vulpes) described as Spirocerca sp. or Spirocerca lupi (Rudolphi, 1819). We characterized spirurid worms collected from red foxes and compared them to S. lupi from domestic dogs by morphometric and phylogenetic analyses. Nematodes from red foxes differed from S. lupi by the presence of six triangular teeth-like buccal capsule structures, which are absent in the latter. Additionally, in female worms from red foxes, the distance of the vulva opening to the anterior end and the ratio of the glandular-to-muscular oesophagus lengths were larger than those of S. lupi (P < 0.006). In males, the lengths of the whole oesophagus and glandular part, the ratio of the glandular-to-muscular oesophagus and the comparison of the oesophagus to the total body length were smaller in S. lupi (all P < 0.044). Phylogenetic analyses revealed that S. lupi and the red foxes spirurid represent monophyletic sister groups with pairwise nucleotide distances of 9.2 and 0.2% in the cytochrome oxidase 1 and 18S genes, respectively. Based on these comparisons, the nematodes from red foxes were considered to belong to a separate species, for which the name Spirocerca vulpis sp. nov. is proposed.