Since 1994, muskrats (Ondatra zibethicus) caught in Flanders (or just across the border) have been dissected with the aim of understanding their ecology. Whilst doing so a large number of parasites were observed in the abdomen of the dissected animals, most notably Taenia taeniaformes.
In 2008 a first individual infected with fox tapeworm (Echinococcus multilocularis) was found, caught just across the regional border in Wallonia. Hence, from 2009 onwards all muskrats caught in Flanders, Wallonia and France by pest controllers of the Flanders Environment Agency (VMM) were collected and dissected with the aim of understanding the prevalence of this parasite.
Visual examination of the livers of 15.948 muskrats caught between 2008 and 2017 revealed 203 infected animals. Regionally we found 82 infected animals out of 9.425 (0,87%) in Flanders. All of the infected animals were found in municipalities bordering the Flemish-Walloon border.
Although EM infection was expected to spread northward from Wallonia to Flanders, this was not observed in the dissected muskrats. Here we argue that keeping muskrat populations low through extensive culling programs may have aided in stopping this spread.