Canadian Wildlife Health Cooperative, Atlantic Region
Distribution and Characterization of Sarcoptic Mange in Red Foxes
Sarcoptic mange ("mange") is an important, emerging disease of red foxes in Prince Edward Island. Mange is caused by a parasitic skin mite (Sarcoptes scabiei) that causes itching, hair loss, skin damage, and sometimes death. Mange has been present in PEI since at least the early 1990's, when it was diagnosed in coyotes in King's County. However, the disease has been sporadic, and was not historically associated with significant mortality. Records from the Canadian Wildlife Health Cooperative, Atlantic (CWHC Atlantic), show the first confirmed case in a PEI fox in 2016. By December 2018, mange had become an increasingly frequent cause of fox mortality, with 25 cases confirmed, and 22 of those in 2018. Notably, at the beginning of this project, mange had only been confirmed in foxes from urban and suburban areas of PEI. However, diagnostic submissions are often biased toward areas with higher human populations, and thus the distributions of the mite and the disease in rural and wilderness areas of PEI had not been fully investigated. Project goals were:
To estimate the geographic distribution of mange and the mange parasite in PEI foxes;
To determine the proportion of sampled foxes from locations in all three PEI counties that have been exposed to the mange parasite;
To provide a comprehensive summary of cases of sarcoptic mange in foxes in PEI; and,
To identify possible risk factors that contribute to the occurrence of sarcoptic mange in foxes in PEI
Laboratory testing was conducted on 58 foxes representing a random distribution of locations across all three PEI counties, using samples obtained from licensed fur trappers in December 2018 and January 2019. Three of the 58 study foxes were confirmed to have sarcoptic mange. All three diseased foxes were from regions immediately adjacent to Charlottetown or Stratford; the disease was not diagnosed in foxes from any other locations during the sampling period (winter 2018-2019). Additional testing revealed mite infection without signs of disease (subclinical infection) in three more foxes, two of which were from King's County.
These findings supported the hypothesis that the disease is more likely to occur in close proximity to urban areas, and that foxes may be, at some stage, infected without external signs of disease. Using archived and ongoing submissions to CWHC Atlantic, a database of fox mange cases was generated, and the disease was shown to manifest severely in foxes, with large numbers of mites per animal.
Through 2019, the spread of the disease to more locations on the island was also documented. The early association of the disease with areas of high human density suggests that fox access to anthropogenic food and other resources may increase the risk of mange. This project provides support for the recommendation to discourage feeding of foxes and to prevent wildlife from accessing human-sourced resources.
Finally, this project helped increase public awareness of this disease, which has elicited increasing reporting of cases of the disease. Public engagement is a fundamental component of wildlife health surveillance.