BackgroundThe spread of vector-borne diseases to new regions has become a global threat due to climate change, increasing traffic, and movement of people and animals. Dirofilaria repens, the canine subcutaneous filarioid nematode, has expanded its distribution range northward during the last decades. The northernmost European locations, where the parasite life-cycle has been confirmed, are Estonia and the Novgorod Region in Russia.ResultsHerein, we describe an autochthonous D. repens infection in a Finnish woman. We also present two cases of D. repens infection in imported dogs indicating the life-cycle in the Russian Vyborg and St Petersburg areas, close to the Finnish border.ConclusionsThe most obvious limiting factor of the northern distribution of D. repens is the summer temperature, due to the temperature-dependent development of larvae in vectors. With continuing climate change, further spread of D. repens in Fennoscandia can be expected.

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In Europe, the zoonotic parasite Dirofilaria repens continues to spread northward. We describe three likely autochthonous canine microfilaremic D. repens infections from Estonia, an European Union country located in the Baltic region of northern Europe. The parasite species was confirmed with sequencing. These are new northernmost D. repens findings in Europe and show that the zoonotic parasite has spread farther north. Infection with D. repens should be included in the list of differential diagnoses for human and animal hosts also in northern Europe.

SummaryDirofilaria immitis (canine heartworm) is a fi larial nematode found in the pulmonary circulation and the heart of susceptible hosts. It represents an important zoonotic vector-borne disease of domestic dogs and several wildlife species. Herein we report for the fi rst time, the fi nding of Dirofi laria immitis worms in a brown bear killed in a vehicle collision in Northern Greece. The worms were morphologically identifi ed; molecular examination, based on the analysis of the mitochondrial genes 12S (433 bp) and CO1 (610 bp), verifi ed the identifi cation by demonstrating 100% similarity to D. immitis specimens deposited in GenBank. Brown bears in Greece occupy habitats that are shared with the potential wild and domestic hosts and the vectors of D. immitis and thus may be particularly susceptible to this parasite. This report contributes to the knowledge of dirofi lariosis spread in Europe and on the epidemiological threats that may affect the survival of the endangered brown bear in Greece.

The intention to increase roach (Rutilus rutilus) consumption is in focus for ecological and economic reasons in Finland. However, its safety as food has not been considered comprehensively. We collected and artificially digested 85 roach halves originating from the south-eastern coast of Finland, and found trematode metacercariae in 98.8% of the samples. Based on polymerase chain reaction (PCR) and sequencing of amplicons generated from the ITS2 gene region, zoonotic parasites of the family Opistorchiidae were identified as Pseudamphistomum truncatum and Metorchis bilis, and also non-zoonotic Holostephanus dubinini (family Cyathocotylidae) and Posthodiplostomum spp. (family Diplostomidae) were identified. The species identity of other trematodes found is currently being investigated. Mixed infections of several trematode species were common. The prevalence of morphologically identified zoonotic P. truncatum was 46%, and zoonotic M. bilis was found in one sequence sample. The high prevalence of zoonotic trematode metacercariae in roach from the Gulf of Finland is alarming. Only thoroughly cooked roach products can be recommended for human or animal consumption from the area.