Different epidemiological pattern of canine dirofilariosis in two neighboring countries in Central Europe—the Czech Republic and Slovakia

The known data resulting from individual surveys of canine dirofilariosis point to the great differences in the epidemiological situation among countries where Dirofilaria parasites emerged approximately at the same time. In this regard, the Czech Republic and Slovakia, neighboring countries situated in Central Europe, could serve as an illustrative example of such a situation. The present study aimed to assess the prevalence of canine dirofilariosis in both countries and to discuss the reasons for potential differences shown. Between October and December 2019, 429 dogs from the Czech Republic and 644 from Slovakia were examined for canine dirofilariosis using the Knott test for microfilariae detection and conventional PCR for the species determination. The results’ analyses showed notable differences. While in the Czech Republic autochthonous Dirofilaria repens cases are reported sporadically and Dirofilaria immitis infections have been confirmed only as imported so far, in Slovakia, both Dirofilaria species seem to have become endemic. Concretely, in the Czech Republic, microfilariae were detected in the peripheral blood of 8 dogs (1.86%): in seven, D. repens was confirmed, and in one dog, mixed infection with D. repens and D. immitis was diagnosed. Seven infected animals came from the eastern part of the country neighboring Slovakia. In Slovakia, microfilariae were detected in 68 (10.56%) dogs examined. DNA analysis confirmed D. repens mono-infection in 38 (5.90%) dogs, single D. immitis infection in 21 (3.26%) animals, and both Dirofilaria species were detected in 9 (1.40%) samples. Although we are unable to determine the cause of the differences, our study confirmed that the long-registered low number of canine dirofilariosis cases in the Czech Republic is not due to insufficient investigation (monitoring), but due to a low prevalence of the parasite in this area.