Retrospective study on the distribution of Dirofilaria immitis in dogs in Hungary.

Europe has experienced the spreading of vector-borne helminths including heartworms (Dirofilaria immitis) from the Mediterranean countries towards the northern ones in the past decades. Recently, the establishment of D. immitis was confirmed in Hungary on the basis of period prevalence studies involving dogs, red foxes (Vulpes vulpes) and golden jackals (Canis aureus). The aim of our retrospective study was to describe the spatial distribution of the parasite and the time course of spreading of D. immitis in Hungary. Necropsy records of 2622 dogs received at our laboratories from 2001 to 2015 were reviewed for heartworm infections. The locality of origin of animals was recorded in a geographic information system database and compared to the results of the period prevalence study involving wild canids. Autochthonous heartworm infection was detected in 27 dogs. The time course analysis indicates that the parasite established in Hungary in 2007. As temperature is one of the most important determinants of the distribution of D. immitis, the climate of the Great Hungarian Plain is the most suitable region for the establishment of D. immitis in Hungary. Our studies revealed that the Great Hungarian Plain became a D. immitis endemic region for 2015. Nevertheless, sporadic cases in wild canids and dogs also occur in other regions of the country.