Crenosoma vulpis in wild and domestic carnivores from Italy: a morphological and molecular study.

Crenosoma vulpis is a metastrongyloid nematode primarily associated with respiratory tract infections of red foxes in North America and Europe. Sporadic cases have also been reported in domestic dogs. The present study aimed to provide morphological, molecular, and epidemiological data on the geographical distribution of this nematode throughout Italy. From 2012 to 2014, 12 of the 138 foxes examined, three dogs and one badger scored positive for C. vulpis. Forty adults were isolated from foxes and the badger, whereas first-stage larvae were detected in the three dogs. All specimens were morphologically identified as C. vulpis, and 28 nematodes were also molecularly characterized by sequencing mitochondrial (12S ribosomal DNA (rDNA)) and nuclear (18S rDNA) ribosomal genes. Four haplotypes were identified based on the 12S rDNA target gene, with the most representative (78.5%) designated as haplotype I. No genetic variability was detected for the 18S rDNA gene. The molecular identification was consistent with the distinct separation of species-specific clades inferred by the phylogenetic analyses of both mitochondrial and ribosomal genes. Data herein reported indicates that C. vulpis has a wide distribution in foxes from southern Italy, and it also occurs in dogs from southern and northern regions of the country. Practitioners should consider the occurrence of this nematode in the differential diagnosis of canine respiratory disease, particularly in dogs living close to rural areas where foxes are present.