The raccoon dog (Nyctereutes procyonoides) as a reservoir of zoonotic diseases in Denmark

Abstract

Raccoon dogs have successfully invaded Europe, including Denmark. Raccoon dogs are potential vectors and reservoir hosts of several zoonotic pathogens and thus have the potential for posing a threat to both human and animal health. This study includes analysis of four zoonotic parasites, 16 tick-borne pathogens and two pathogen groups from 292 raccoon dogs collected from January 2018 to December 2018. The raccoon dogs were received as a part of the Danish national wildlife surveillance program and were hunted, found dead or road killed. The raccoon dogs were screened for <i>Alaria alata</i> and <i>Echinococcus multilocularis</i> eggs in faeces by microscopy and PCR, respectively, <i>Trichinella</i> spp. larvae in muscles by digestion, antibodies against <i>Toxoplasma gondii</i> by ELISA and screening of ticks for pathogens by fluidigm real-time PCR. All raccoon dogs tested negative for <i>E. multilocularis</i> and <i>Trichinella</i> spp., while 32.9% excreted <i>A. alata</i> eggs and 42.7% were <i>T. gondii</i> sero-positive. Five tick-borne pathogens were identified in ticks collected from 15 raccoon dogs, namely <i>Anaplasma phagocytophilum</i> (20.0%), <i>Babesia venatorum</i> (6.7%)<i>, Borrelia miyamotoi</i> (6.7%)<i>, Neoehrlichia mikurensis</i> (6.7%) and <i>Rickettsia helvetica</i> (60.0%). We identified raccoon dogs from Denmark as an important reservoir of <i>T. gondii</i> and <i>A. alata</i> infection to other hosts, including humans, while raccoon dogs appear as a negligible reservoir of <i>E. multilocularis</i> and <i>Trichinella</i> spp. infections. Our results suggest that raccoon dogs may be a reservoir of <i>A. phagocytophilum</i>.