Prevalence, distribution and risk associated with tick infestation of dogs in Great BritainArchived

Prevalence, distribution and risk associated with tick infestation of dogs in Great BritainSmith FD1, Ballantyne R2, Morgan ER1, Wall R1. 1 Veterinary Parasitology and Ecology Group, School of Biological Sciences, University of Bristol, Bristol, U.K. 2 Merial Animal Health Ltd, Harlow, U.K. Medical and Veterinary Entomology 2011 Mar 21. doi: 10.1111/j.1365-2915.2011.00954.x. [Epub ahead of print]

Current concerns over the potential impacts of climate change and the increased movement between countries of people and companion animals on the distribution of ectoparasites, highlight the need for accurate understanding of existing prevalence patterns. Without these future changes will not be detected. Here, the distribution and prevalence of tick infestations of domestic dogs in Great Britain were examined. A total of 173 veterinary practices were recruited to monitor tick attachment to dogs in their local areas between March and October 2009. Practices selected five dogs at random each week from those brought to the surgery and undertook a thorough, standardized examination for ticks. Each veterinary practice participated for 3 months before being replaced. Any ticks identified were collected and a sample sent to the investigators for identification, along with a clinical history of the dog. A total of 3534 dogs were examined; 810 dogs were found to be carrying at least one tick. Ixodes ricinus (Linnaeus) (Acari: Ixodidae) was identified in 72.1% of cases, Ixodes hexagonus Leach in 21.7% and Ixodes canisuga Johnston in 5.6% of cases. Five samples of Dermacentor reticulatus (Fabricius) (Acari: Ixodidae) were also found, adding to the growing evidence that an established population of D. reticulatus now exists in south-eastern England. Almost all the ticks found were adults. Overall, 19.2% of the veterinary practices reported no tick detections, 50% reported that ≥14.9% of the dogs seen were infested and 14.6% reported that >50% of the dogs inspected carried ticks. The estimated incidence of tick attachment was 0.013 per day in March (lowest) and 0.096 per day in June (highest). A number of risk factors affected the likelihood of tick attachment on dogs. Gundog, terrier and pastoral breed groups were more likely to carry ticks, as were non-neutered dogs. Dogs with shorter hair were less likely to have ticks, and dogs were most likely to carry a tick in June. This study is of value because, unusually, it presents the results of a randomized sample of dogs and gives a prevalence which is higher than those previously recorded in Great Britain.

Arthropod Vector Surveillance network (VBORNET)comment: This study presents results from active surveillance conducted on dogs from March to October 2009 concerning their tick infestation. Thanks to a strict sampling protocol (especially the randomized sample of dogs), it was possible to assess a monthly tick attachment rate (=infestation incidence) and a tick infestation prevalence. Such data are usually rare even essential for designing any further field studies on tick ecology and tick-borne diseases. These results show that the tick infestation prevalence found in dogs from Great Britain is much higher than expected, suggesting an under-estimation of the tick burden for domestic animals and also humans. Useful information should have been also to distinct tick infestation for each tick species, which is commonly requested when studying a disease transmitted by specific tick species. However, this study provides important insights for Great Britain and is very complementary to recent work published by the Health Protection Agency of tick distribution during the 10 last years in UK.