Ticks Flashcards
Outline how ticks feed
- Chelicerae cut hole in skin
- Hypostome enters hole, held in by backwards facing teeth
- Cement produced by some to increase hold
- Inject saliva
- Feed through hypostome
What is contained in the saliva of ticks?
- Vasodilators (leading to swelling)
- Immunosuppressive proteins
- Neurotoxins in some
- Pathogens
What are the direct effects of ticks?
- Inflammation at attachment site
- Anaemia
- Tick paralysis from some ticks (Australia)
What are teh indirect effects of ticks?
- Biological vectors for protozoa, bacteria, viruses
Why are ticks usually biological rather than mechanical vectors?
Pathogen rarely survives moulting between feeds if mechanical transmission
List the most common tick species
- Ixodes ricinus
- I. hexagonus
- I. trianguliceps
- I. canisuga
- Haemaphysalis punctata
- Dermacentor reticulatus
- Rhipicephalus sanguineus
How can ticks be differentiated?
- Size, shape, colour, ornamentation
- Face: shape of head and mouth parts
- Back end: i.e. anal groove
Give a brief overview of Ixodes ricinus
- Most commonly seen in vet practice
- Castor bean tick
- Wide range of hosts incl. humans
Give a brief overview of Ixodes hexagonus
- Common in UK
- Hedgehog tick
- Also found on dogs
- Rarely on humans
- More selective than ricinus
Give a brief overview of Ixodes trianguliceps
- Not of veterinary importance
- Most common tick in UK
- ONly on wild rodents
- Nidiculous
- Important in epidemiology of some infections
Give a brief overview of Ixodes canisuga
- Infrequent and only in south UK
- Dogs and badgers
Give a brief overview of Haemaphysalis punctata
- SE England and Wales, widely in Europe
- Red sheep tick, ruminants, rabbits, humans
Give a brief overview of Dermacentor reticulatus
- W Europe, rarly UK
- W Wales, SW England if anywhere
- Dogs and other large mammals incl man
Give a brief overview of Rhipicephalus sangiuneus
- S Europe, cannot survive outsde in temperate climates
- Most commonly on dogs imported from Med
- May be found where kennels kept particularly warm
What is transstadial transmission?
Transmission between stages i.e. larva to nymph, nymph to adult
What is transovarial transmission?
Vertical transmission via eggs, so larvae are infected and infectious
Describe the life cycle of 1-host ticks
- Female lays eggs (not on host)
- Larvae hatch
- feeding, moulting on host
- Nymph
- Male and female reattach
- Feeding, mating
- Female drops off
- Lays eggs
Describe the life cycle of 2-host ticks
- Female lays eggs (not on host)
- Larvae onto first host
- Feeding, moulting on host
- Onto second host
- Feeding, mating
- Female drops off and lays eggs
Describe the life cycle of 3-host ticks
- Female lays eggs off host
- Larvae feed on first host, drop off
- Nymph moulting
- Feed on second host, drop off
- Adult moulting
- Male and female attach to third host
- Feeding and mating
- Female drops off and lays eggs
Where does mating take place?
On the host
Describe nidiculous ticks
- In the nest of host
- When not feeding, tick stays in teh host’s nest/burrow
- Most Argasid ticks, have multiple nymph stages
Describe non-nidiculous ticks
- When not feeding are in open environment
- Fall off wherever host happens to be when tick finished feeding
- May “quest” to find host, or wait for host to pass by
- Usually long grass, moorland areas, low shrubby terrain
- Each stage in life cyce may have different host species
Compare hard and soft ticks
- Soft: soft leather bodies, legs hidden under tick, usually on birds
- Hard: scutum covers whole of back in males
Compare the scutum of male and female hard ticks
- Female hard tick scutum only covers half of body
- Will cover less as she feeds and swells
- In male covers whole back
Describe soft ticks
- Argasidae
- Most are nest parasites
- Swell when take on blood meal
- Lots of nymph stages