Seasonal and spatial distribution of ixodid tick species feeding on naturally infested dogs from Eastern Austria and the influence of acaricides/repellents on these parameters.

BACKGROUND: Effective control of tick infestation and pathogen transmission requires profound knowledge of tick biology in view of their vector function. The particular time of the year when the different tick species start to quest and the favoured sites on the canine host are of major interest. The efficacy of acaricides/repellents to control ticks in the field requires observation.

METHODS: To address these issues, 90 dogs, grouped in "untreated", "acaricide/repellent" (permethrin) and "acaricide only" (fipronil) animals and subjected to tick infestation under natural conditions in Burgenland (Eastern Austria), were examined. The number and species of ticks occurring during and outside the protection time was evaluated during a period of 11 months and the biting location on the dogs' skin was recorded.

RESULTS: Of the 700 ticks collected, the most common species in that particular walking area was Ixodes ricinus, followed by Dermacentor reticulatus and Haemaphysalis concinna. Regarding the on-host activity, D. reticulatus displayed more infestations in early spring and late autumn, whereas I. ricinus occurred almost one month later in spring and one month earlier in autumn. H. concinna followed a monophasic pattern of activity with a peak in summer. The preferred feeding sites of the ticks on the dogs were on the head, neck, shoulder and chest. This distribution over the dog's body was not influenced by the use of the drugs, although on the whole fewer ticks (22.5% of all ticks) were found during the protection time. Interestingly, differences occurred with the use of drugs compared to non-protected dogs with regard to the infestation over the year. Acaricide-treated dogs displayed a higher prevalence in April, May and September, whereas dogs of the acaricide/repellent group showed a higher infestation in March, July, October and November.

CONCLUSION: The different tick species display different on-dog activity peaks over the year, during which particular canine diseases can be expected and predicted, considering the specific incubation times for each pathogen.The tick species occurring in this study do not seem to choose particular sites on the dogs. Their arrival place seems to represent the attachment and consequently the feeding sites. The use of acaricides leads to a significantly (p<0.01) lower number of infesting ticks but no change of the distribution pattern on the dogs was observed.