In the course of our studies on ticks and tick-borne diseases of dogs in Hungary the following new results have been achieved:
• A figured practical identification key has been designed for the sixteen hard tick species which occur on dogs in Europe.
• In 29 veterinary clinics from six districts of Budapest and 13 counties, 1779 tick specimens were collected from 606 dogs. Most hosts were usually infested with a single female and very few of them had many ticks. The most preferred sites of tick attachment in decreasing order were head, neck and legs. Ixodes ricinus and Dermacentor reticulatus were the most common species. Ixodes canisuga, Haemaphysalis concinna, Ixodes hexagonus, Ixodes acuminatus and Dermacentor marginatus were also found. New data have been provided about the geographical distribution of Dermacentor reticulatus, because the specimens of this species were collected in north-eastern and south-eastern parts of the country too where they had not been found before.
• Field collections in 31 locations provided new data on the geographical and seasonal occurrence of I. ricinus, D. reticulatus and other tick species as well.
• The occurrence of small canine piroplasms in two dogs was described for the first time in Hungary. These were autochtonous infestations but we need further investigations to know the species, occurrence, vector and origin of this pathogen.
• The subspecies Babesia canis canis was identified to be the causative agent of babesiosis caused by large Babesia sp. in dogs using molecular biological methods. It was also proven with molecular methods that the geographical distribution of canine babesiosis is larger in the country than it has been previously known.
• Babesia DNA was detected in free-living and engorged D. reticulatus females for the first time in the country. Presence of B. canis canis in engorged D. reticulatus specimens removed from dogs was also demonstrated with molecular methods.
• Molecular evidence was found for the presence of Borrelia sp. in free-living and engorged I.
ricinus females for the first time in Hungary. Three species, B. burgdorferi s.s., B. afzelii and B.
garinii were identified with sequence analysis which are pathogenic to both dogs and humans.
The presence of dogs around humans increases the number of their ectoparasites in the houses, flats and surroundings (Shaw et al., 2001). An increase in the number of ticks in the vicinity of humans increases the risk of a human tick infestation. So, dogs can be considered as reservoirs of ticks in human environments posing the risk of new and re-emerging infectious diseases. Due to climatic changes towards global warming, imported tick species may adapt to new area and might be considered as epidemiological markers for a number of infectious agents transmitted by them (Kenny et al, 2004b). This is what makes monitoring, mapping and identification of ixodid ticks necessary in the future.
Dogs in Hungary were found to be infested with species of ticks that included competent disease vectors. With support of molecular biological methods (Sparagano et al., 1999; Monis et al.
2005), infections of various tick-borne parasites should be studied in both the vector and the host to clarify the epidemiological role of both the tick and the dog in the transmission of these pathogens.
In order to gain more information about the occurrence of hard ticks and their epidemiological and epizootiological role, we plan to continue this study with increased number of field collection sites and veterinary clinics in new areas. Deepening our understanding of the ecological needs of the tick species found on dogs in Hungary would further enhance the prevention of tick-borne diseases in Europe.
Several factors have probably contributed to the emergence of canine babesiosis and other tick-borne diseases in Europe. They include the increase in outdoor activities and travels among Europeans resulting in an increased contact with ticks and an increased risk of transmitted diseases;
the development of new techniques for the detection of organisms; the use of molecular methods for their characterization; as well the curiosity and awareness of clinicians about atypical cases (Parola and Raoult, 2001). Numbers of Babesia spp., Rickettsia spp., Anaplasma spp. and Ehrlichia spp. of unknown pathogenicity have been found in ticks and represent potential candidates for new human and/or canine tick-borne diseases to be described in the future. Finally, global climate changes could also have an influence on the epidemiology of tick-borne diseases in Europe (Lindgren et al., 2000). Indeed, it was recently suggested that increased average temperature during the winter would be responsible for an extension northern limit of the area of distribution of I. ricinus, as well as an increased population density of these ticks from 1980s to 1990s (Lindgren et al., 2000). Thus, this could lead to higher incidence of the diseases transmitted by I. ricinus (and potentially other species), as well as an increased risk area. For example, some authors hypothesized that this could explain the higher incidence of the tick-borne viral encephalitis transmitted by I. ricinus in Sweden
borne diseases and contribute to the emergence of new diseases in the future.
Further research is needed to know the origin of small babesiae occurring in Hungary. With the advances of molecular techniques we plan to characterize this parasite with PCR and sequencing. A targeted sampling method will be needed in the veterinary clinics to select the small Babesia infections from the relatively common B. canis infection.
For both veterinary and public health reasons, the study of B. burgdorferi s.l. in host seeking ticks became an urgent and necessary issue in Hungary. We intend to collaborate with Lyme disease specialists, human and animal diagnostic laboratories to launch further molecular surveys and gain more information about the reservoir species and the spatio-temporal distribution of Lyme disease spirochetes in the country.