Emerging risk of Dirofilaria spp. infection in Northeastern Europe: high prevalence of Dirofilaria repens in sled dog kennels from the Baltic countries

AbstractDirofilariasis is a fast-spreading disease of dogs and humans in Europe. We investigated whether Dirofilariaspp. have spread northwards in Europe, invading the Baltic countries. Altogether, 424 blood samples were collected from eight countries in the period 2017–2019, including 227 samples from sled dogs and 197 samples from other dogs. PCR amplification and sequencing were conducted employing three genetic markers (mitochondrial [mt] 12S rDNA, mt cytochrome c oxidase subunit I [COI] gene and mt dehydrogenase subunit I [NAD1] gene). The SNAP test (IDEXX) for detection ofD. immitisinfections was also implemented. The DNA ofD. repenswas detected in 59 of 424 dogs (prevalence 13.9%).D. repenswas found in sled dogs from Lithuania, Latvia, Poland and Belarus. Only one dog from Estonia was infected, apparently an imported case. The highest prevalence was recorded in Lithuania (38%). Among pet dogs from the Ukraine, six dogs tested positive (3.8%). Our study has revealed a high prevalence ofD. repensinfections in Lithuania and Latvia, but no evidence for spread of the heartwormD. immitis. We conclude that sled dog kennels constitute hot spots forD. repenstransmission.