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Home » Archive » 2013

TDK conference 2013

Molecular epidemiological investigations of canine hepatozoonosis during its first detection in Hungary
Farkas Viola - year 5
SzIU, Faculty of Veterinary Science, Department of Parasitology and Zoology
Supervisor: Sándor Hornok DVM

Abstract:

Hepatozoon canis, the causative agent of canine hepatozoonosis in Europe, is a protozoan parasite of the phylum Apicomplexa. Former scientific reports supported the view, that autochthonous infections of dogs with H. canis are possible only in the Mediterranean region, due to the geographical occurrence of its main vector tick, Rhipicephalus sanguineus (restricted to southern parts of our continent). However, during the past few years sporadic cases of H. canis infections were reported from countries north of the formerly recognized endemic region. In particular, a Croatian survey in 2009 indicated the occurrence of canine hepatozoonosis near the Hungarian border, although with low prevalence. The aim of the present work was to investigate, if dogs are infected with H. canis in Hungary or not, and what epidemiological factors may influence this situation.

Blood samples and ticks were collected from dogs along the southern Hungarian border (Zala, Somogy, Baranya, Csongrád counties), in order to screen them for the presence of H. canis with molecular methods. Haematological evaluation of blood samples was also carried out. Although the individual dogs were chosen randomly, our purpose was to include animals that are kept extensively, thus having frequent contact with ticks. In this way 100 shepherd, 12 hunting and 14 stray dogs participated in the study.

Out of the 126 blood samples 33 (26%) were PCR positive, with highest prevalence among shepherd dogs. Three genotypes were identified with sequencing. In Dermacentor marginatus larvae/nymphs and D. reticulatus nymphs, H. canis was present only if they had been collected from PCR-positive dogs, and the genotypes were identical in the ticks and their hosts. However, two Haemaphysalis concinna nymphs removed from a PCR-negative dog were found positive for H. canis, and the genotype detected in specimens of this tick species differed from that in the blood of their respective host. Dermacentor adults were also collected from the vegetation, but turned out to be non-infected. Taking these results into account Ha. concinna is a new, potential vector of H. canis. Apart from this the role of other epidemiological factors is also postulated, as the prevalence of canine hepatozoonosis was higher in Hungary, than in neighbouring Croatian regions. Most probably predation may be an alternative mode of transmission (adding to tick-borne cases), as this mode of infection was reported for the other Hepatozoon species of dogs, H. americanum. This would also explain why shepherd dogs were the most infected in the present study (i.e., they have access to prey and dead animals).

In summary, it was verified for the first time, that canine hepatozoonosis can be endemic north of the Mediterranean countries, even with high prevalence. It is assumed that this is not due to climate change and northward spreading of the tick vectors, but due to previously unknown epidemiological factors.



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