Pathology of sarcoptic mange in red foxes (Vulpes vulpes): macroscopic and histologic characterization of three disease stages

Sarcoptic mange is a highly contagious skin disease that can have a devastating impact on affected wild mammal populations. There are notable variations in the clinical and pathologic picture of sarcoptic mange among species and among conspecifics. However, the origin of these variations is unclear. We propose a classification scheme for skin lesions associated with Sarcoptes scabiei infestation to provide a basis for a subsequent risk factor analysis. We conducted a case-control study focused on macroscopic and histologic examination of the skin, using 279 red foxes (Vulpes vulpes) found dead or shot in Switzerland between November 2004 and February 2006. All animals were submitted to gross necropsy following a detailed protocol. Selection criteria for cases (n=147) vs. controls (n=111) were the presence or absence of mange-like lesions, mite detection by isolation or histologic examination, and serologic testing for S. scabiei antibodies. Characteristic features of mange lesions were scored macroscopically in all foxes and histologically in 67 cases and 15 controls. We classified skin lesions and associated necropsy findings into three types of mange: A) early stage (n=45): focal-extensive skin lesions, thin crusts, mild to moderate alopecia, few mites, numerous eosinophils, and mild lymph node enlargement; B) hyperkeratotic, fatal form (n=86): generalized skin lesions, thick crusts with or without alopecia, foul odor, abundance of mites, numerous bacteria and yeasts, numerous lymphocytes and mast cells, severe lymph node enlargement, and emaciation; C) alopecic, healing form (n=16): focal lesions, no crusts, severe alopecia, hyperpigmentation and lichenification, absence of mites, mixed cell infiltration, and rare mild lymph node enlargement. We hypothesize that after stage A, the animal either enters stage B and dies, or stage C and survives, depending on largely unknown extrinsic or intrinsic factors affecting the host ability to control mite infestation.

Trichinella britovi in a red fox (Vulpes vulpes) from Portugal

Trichinellosis is one of the most important foodborne parasitic zoonoses, caused by nematodes of the genus Trichinella. Pigs and other domestic and wild animals, including red foxes (Vulpes vulpes), are sources of Trichinella infection for human beings. Trichinella britovi is the major agent of infection in sylvatic animals and the most important species circulating in the European wildlife. The present study aimed at assessing Trichinella spp. infection in red foxes from the North of Portugal. Forty-seven carcasses of wild red foxes shot during the official hunting season or killed in road accidents were obtained between November 2008 and March 2010. In order to identify the presence of Trichinella spp. larvae in red foxes, an individual artificial digestion was performed using approximately 30g of muscle samples. Larvae of Trichinella spp. were detected in one (2.1%) out of the 47 assessed foxes. After a multiplex polymerase chain reaction analysis, T. britovi was molecularly identified as the infecting species. The recognition of T. britovi in a red fox confirms that a sylvatic cycle is present in the North of Portugal and that the local prevalence of Trichinella infection in wildlife must not be ignored due to its underlying zoonotic risks.