First report of Metathelazia capsulata in red foxes (Vulpes vulpes) in Europe and new contributions to its identification

Influence of environmental factors on the occurrence of gastrointestinal and cardiopulmonary nematodes in the red fox in the semi-arid Mediterranean areas of the Iberian Peninsula

Human-induced ecosystem fragmentation is one of the drivers causing wildlife migration from their natural habitats to urban areas, among other reasons. The red fox (Vulpes vulpes) is the most abundant wild canid in the semi-arid Mediterranean areas of the Iberian Peninsula. Water scarcity may result in areas shared by synanthropic fox populations and domestic animals becoming hotspots for parasite transmission. This study describes the gastrointestinal and cardiopulmonary nematode species affecting fox populations in these semi-arid areas and the influence of environmental variables on parasite abundance. A total of 167 foxes collected from 2015 to 2021 in the Region of Murcia (SE Spain) were analysed. Parasite abundance and spatial distribution were evaluated using environmental variables and host characteristics with a Generalised Linear Model and the Moran index. Eleven species (seven from the gastrointestinal tract and four from the cardiopulmonary tract) were described. The influence of biotic and abiotic variables was studied for Angiostrongylus vasorum, Crenosoma vulpis, Uncinaria stenocephala, Toxocara canis and Toxascaris leonina. Temperature, humidity and areas of forest or agricultural land influenced the abundance of these parasites, providing optimal conditions for free-living stages of the direct life cycle nematodes and intermediate hosts. Absolute abundance distribution maps showed defined locations for C. vulpis, T. canis and T. leonina. The results for U. stenocephala, T. canis and T. leonina were particularly important as their higher abundance levels were found close to anthropized areas, which need to be carefully evaluated to prevent transmission of these nematodes between domestic and wild canids and human health.

Complete mitochondrial genome of Metathelazia capsulata (Pneumospiruridae) and comparison with other Spiruromorpha species

Metathelazia capsulata (family Pneumospiruridae) is a lungworm parasitizing the bronchi and bronchioles, described in four species of wild carnivores. Very little molecular data are available on this nematode and none on other species of the Pneumospiruridae family. In this work, we describe for the first time the complete mitogenome (mitochondrial genome) of M. capsulata, being the first described of the family Pneumospiruridae. The mitogenome of M. capsulata has 13,659 bp in length, an A + T content of 79.2%. The mitogenome included 12 protein-coding genes (PCGs) (lacking the atp8 gene), 22 tRNA genes, 2 rRNA genes (all the genes are coded by the heavy strand), and an AT-rich region. The PCGs varied in size (232 bp-1645 bp). Only the tRNA-Trp has the standard cloverleaf secondary structure, while the other 21 do not. The AT-rich region, with a 90.5% A + T content and a length of 389 bp, is located between the cox3 and tRNA-Ala genes. Comparison with the mitogenomes of 29 species of Spiruromorpha infraorder, belonging to different families, demonstrates that M. capsulata mitogenome shared the common characteristics of most of them. The phylogeny constructions yielded phylogenies that were in agreement with the obtained previously by using sequences and gene order data of mitogenomes.

What is the sensitivity and exactness of post-mortem diagnostic method for cardiopulmonary nematodes in wild carnivores? towards the gold standard

Cardiopulmonary nematodes cause health and fitness disorders in wild and domestic carnivores. The red fox (Vulpes vulpes) participates in the spread of these shared parasites at the domestic-wildlife interface. This study aimed to evaluate the sensitivity of post-mortem diagnostic method for detecting lungworms in carnivores, and its exactness to estimate the parasite intensity of each nematode species. Cardiorespiratory system of fifty-one foxes were examined through three consecutively methodological steps: first, the tracheobronchial tree, pulmonary arteries and their branches were opened (OT); next, lung parenchyma was immersed in water and squeezed (WS); finally, the parenchyma was artificially digested in a pepsin and chlorhydric acid solution (AD). Eucoleus aerophilus, Angiostrongylus vasorum, Crenosoma vulpis and Metathelazia capsulata were identified. The number of recovered nematodes in each step were 454 (OT), 285 (WS) and 141 (AD). The use of OT and WS helped to improve parasite intensity results and decreased false negative cases. Accordingly, when OT and WS were used together, the sensitivity in the detection of parasitized foxes was 96.1%, while the exactness of parasite intensity was 84%. When AD was performed, although sensitivity does not rise, results were more exact, increasing the total number of detected parasites by 16%. Moreover, AD improved the sensitivity in the detection of A. vasorum and M. capsulata, as well as quantifying more exactly the parasite intensity (92.5% and 92.3% of exactness without AD, respectively). Our study provides valuable information that should be taken into account when planning epidemiological studies based on cardiopulmonary nematode detection in carnivores.