Introduction

Classification

Taxonomy

• Class:Arachnida; subclass:Acari
• Order:MetastigmataorIxodida
• Family:Ixodidae
• Genus:Dermacentor
• Species:D. reticulatus(Fabricius,1794)

Active Forms

Resting Forms

Clinical Effects

Epidemiology

Habitat

• Preferred hosts for the adults are medium to large mammals including dogs, foxes, cattle, sheep, horses, goats, deer, pigs, hares, hedgehogs and uncommonly humans.
• Nymphs and larvae usually parasitize rodents, insectivores and mustilids but birds are occasional hosts as are larger mammals.
• Preferred habitats include grassland, pastures and deciduous or mixed forests interspersed with meadows.
• Preferred environment is one of high humidity with mild winters.
• Clinical babesiosis commonly has a seasonal pattern which co-incides with peak adult tick activity in Spring and Autumn.

Lifecycle

• Three host tick 3-host tick, ie each stage falls off the host into the environment after feeding, molts and finds another host for the next stage.
• Development from egg to unfed adult usually takes 17-35 weeks in favorable conditions
• Life cycle (egg to adult) can be completed in one year but two years may be necessary in less favorable areas. Unfed adults may survive up to two years in the Mediterranean margins of its distribution.

Seasonal activity levels

• Adult ticks appear on preferred hosts in early Spring.
• Main activity period for the adults is March-June with a secondary peak in Autumn (August-November).
• Often fewer males are present than females.
• Immature stages are most active from May-October.
• In southern marginal areas of its distribution, activity is between October and March.

Pathological effects

• Pruritus in susceptible dogs, local hypersensitivity with tick-bite site ulceration.
• Transmission of Babesia and Theileria in dogs (horses and cattle):
  • Canine babesiosis is associated with moderate to severe hemolytic anaemia which may be fatal in previously unexposed animals. Sub-clinical Babesia infections may recrudesce following stress, eg surgery or immunosuppression.
• Several viral pathogens including those causing tick borne encephalitis, Russian spring-summer encephalitis and Omsk Hemorrhagic fever.
• May play a role in transmission of tularemia (Francisella tularensis) and Mediterranean spotted fever (Rickettsia conoriinfections).

Control

Control via chemotherapies

• There are several safe, very effective acaricides with long-duration of activity across multiple tick species for use on dogs using topical formulations (spot-ons, collars, sprays) containing:
  • Amitraz Amitraz.
  • Fipronil Fipronil.
  • Synthetic pyrethroids especially permethrin (have repellent activity as well) Permethrin.
  • Pyriprole.
    Fipronil is the only product licensed as an acaricide for cats.

Control via environment

Largely impractical except where infestation is confined to a limited space such as kennels.

• Outdoor premises control of ticks includes use of carbamates and synthetic pyrethroids. Older insecticides have efficacy but their use is controlled by regulatory approval.
• Synthetic pyrethroids for indoor control (and for use in cars, kennels and cages). Older drugs under regulatory control but may be used by commercial pest exterminators.

Vaccination

• None available for tick control. See control of tick-borne diseases.

Other countermeasures

• Mechanical tick removal to control exposure to pathogens.

Diagnosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Smith F D, Ballantyne R, Morgan E R et al (2011) Prevalence, distribution and risk associated with tick infestation of dogs in Great Britain. Medical and Veterinary Entomology 25 (4), 377-384 PubMed.

Other sources of information

• Wall R and Shearer D S (Editors) (2008) Veterinary Ectoparasites: Biology, Pathology and Control, Edition 2, Blackwell Science Ltd, London, pp 71-74.
• Hillyard P D (1996) Ticks of North-west Europe. Natural History Museum, Field studies Council Shrewsbury, pp 118.
• Baker A S (1990) Mite and ticks of domestic animals: An identification and information source. The Natural History Museum, The Stationery Office, London, pp 176-179.