Current trends in canine dirofilariosis in Austria—do we face a pre-endemic status?

Abstract

A retrospective study based on cases of canine dirofilariosis presented to the University of Veterinary Medicine, Vienna or diagnosed by private practitioners throughout Austria, from 1998 to 2018 was conducted to investigate the long-term development and current state of canine dirofilarial infections in Austria. Included in this study were 146 dogs which were tested positive for D. immitis and/or D. repens. The most commonly used diagnostic methods and the probable geographical origins of the infections were evaluated and the treatment protocols applied were compared with each other and with the literature. The results show that most infections were found due to screening for common travel infections using antigen-ELISA or PCR-testing, or by the incidental finding of microfilariae. Remarkably, only 24.3% of all cases presented showed clinical signs indicating canine dirofilariosis. Regarding the origin and travel history of the dogs, thirteen different countries could be identified. The three treatment protocols used showed a similar outcome after 8 months of treatment and minor side effects, which is consistent with the literature. An alarming increase in reported infections with both D. immitis and D. repens in Austria was noted since 2014. The number of documented cases had almost tripled by 2018, raising severe concerns about the threat of it becoming endemic in Austria. Therefore, the existing recommendations in current guidelines regarding canine dirofilariosis should be widely publicised and more strictly enforced. Prophylactic measures for dogs travelling abroad and diagnostic and therapeutic strategies for dogs imported from endemic countries should be obligatorily established throughout Europe, to reduce the risk of further spread of canine filarial infections to non-endemic regions.

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

“…We did not detect any D. immitis infection in dogs sampled in 2019, although D. immitis is believed to follow D. repens in its expansion in Central and NE Europe 2 , 10 , 16 , 17 , 34 . However, D. immitis infections in sled dogs participating in training and races should be easily noticed by owners due to exercise intolerance, a characteristic consequence of heartworm infection 50 .…”

Human dirofilariosis in Austria: the past, the present, the future

“…A recent study on canine dirofilariosis conducted in Austria revealed that the number of dogs infected with D. repens and D. immitis has increased since 2014, reaching a peak in 2018 [ 41 ]. The infected animals had mostly been imported as shelter or stray dogs by animal welfare organizations or had an international travel history, both facilitated by the Pet Travel Scheme (Regulation [EU] No.…”

“…576/2013 of the European Parliament and of the Council as of 2013). In the majority of cases, the infected dogs were relocated from or had traveled to regions known to be endemic for Dirofilaria spp., such as Hungary, Greece, Croatia, Serbia, Slovenia, Spain, Romania and Slovakia [ 25 , 41 – 47 ]. Dogs are the main reservoir hosts for Dirofilaria spp.…”

“…and can easily introduce these parasites to previously non-endemic countries as competent vectors are available almost worldwide. However, in several of the cases presented herein, no travel history was traceable, suggesting the occurrence of autochthonous canine infections [ 25 , 41 , 42 ]. In contrast, autochthonous human dirofilariosis is still rare in Austria; to date, there has been only one presumably autochthonous case with the patient reporting no travel activities [ 15 ].…”

Focus on Common Small Animal Vector-Borne Diseases in Central and Southeastern Europe

“…Canine heartworm disease has been considered endemic in Hungary since 2007; since then, the number of cases has increased dramatically [49]. Sonnberger et al (2020) show that just by importing dogs from Hungary to Austria, the number of positive tested dogs in Austria increased by a factor of 20-30 over the last ten years [50]. The fi rst records on autochthonous D. repens infections in Austrian dogs were published in 2009, near the border of Hungary and Slovakia; confi rmation of an endemic status was achieved by the detection of skinworm DNA in mosquitos a few years later [51,52].…”