Molecular detection of tick-borne pathogens Borrelia afzelii, Borrelia miyamotoi and Anaplasma phagocytophilum in Eurasian red squirrels (Sciurus vulgaris)

Eurasian red squirrels (Sciurus vulgaris) are common hosts of ixodid ticks and could thus carry tick-borne disease agents. The relative contribution of the red squirrel, a medium-sized rodent species, to the transmission dynamics of tick-borne pathogens in Europe yet remains unclear. We analysed spleen and liver samples from 45 dead squirrels collected in Flanders, Belgium, during tick activity season and detected the presence of Borrelia burgdorferi s.l. in the spleen of two squirrels (4.4%). One of the sequences could be identified as Borrelia afzelii. Borrelia miyamotoi was detected in the spleen of three squirrels (6.7%) and Anaplasma phagocytophilum in four spleen samples (8.9%). Both A. phagocytophilum ecotype I and II were found. We could not detect the presence of Candidatus Neoehrlichia mikurensis or tick-borne encephalitis virus in any of the squirrels. Our results suggest that Eurasian red squirrels can host B. afzelii, as already proposed by previous studies, but we could not confirm the previous established association between squirrels and B. burgdorferi sensu stricto. Our results demonstrate the epidemiological importance of the red squirrel, particularly in (sub) urban areas, since they can harbour a similar community of tick-borne pathogens as do mice and voles and can act as hosts for A. phagocytophilum ecotype I, which has important implications for human health risk.