Ticks Flashcards

1
Q

Outline how ticks feed

A
  • 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
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2
Q

What is contained in the saliva of ticks?

A
  • Vasodilators (leading to swelling)
  • Immunosuppressive proteins
  • Neurotoxins in some
  • Pathogens
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3
Q

What are the direct effects of ticks?

A
  • Inflammation at attachment site
  • Anaemia
  • Tick paralysis from some ticks (Australia)
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4
Q

What are teh indirect effects of ticks?

A
  • Biological vectors for protozoa, bacteria, viruses
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5
Q

Why are ticks usually biological rather than mechanical vectors?

A

Pathogen rarely survives moulting between feeds if mechanical transmission

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6
Q

List the most common tick species

A
  • Ixodes ricinus
  • I. hexagonus
  • I. trianguliceps
  • I. canisuga
  • Haemaphysalis punctata
  • Dermacentor reticulatus
  • Rhipicephalus sanguineus
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7
Q

How can ticks be differentiated?

A
  • Size, shape, colour, ornamentation
  • Face: shape of head and mouth parts
  • Back end: i.e. anal groove
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8
Q

Give a brief overview of Ixodes ricinus

A
  • Most commonly seen in vet practice
  • Castor bean tick
  • Wide range of hosts incl. humans
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9
Q

Give a brief overview of Ixodes hexagonus

A
  • Common in UK
  • Hedgehog tick
  • Also found on dogs
  • Rarely on humans
  • More selective than ricinus
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10
Q

Give a brief overview of Ixodes trianguliceps

A
  • Not of veterinary importance
  • Most common tick in UK
  • ONly on wild rodents
  • Nidiculous
  • Important in epidemiology of some infections
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11
Q

Give a brief overview of Ixodes canisuga

A
  • Infrequent and only in south UK

- Dogs and badgers

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12
Q

Give a brief overview of Haemaphysalis punctata

A
  • SE England and Wales, widely in Europe

- Red sheep tick, ruminants, rabbits, humans

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13
Q

Give a brief overview of Dermacentor reticulatus

A
  • W Europe, rarly UK
  • W Wales, SW England if anywhere
  • Dogs and other large mammals incl man
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14
Q

Give a brief overview of Rhipicephalus sangiuneus

A
  • S Europe, cannot survive outsde in temperate climates
  • Most commonly on dogs imported from Med
  • May be found where kennels kept particularly warm
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15
Q

What is transstadial transmission?

A

Transmission between stages i.e. larva to nymph, nymph to adult

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16
Q

What is transovarial transmission?

A

Vertical transmission via eggs, so larvae are infected and infectious

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17
Q

Describe the life cycle of 1-host ticks

A
  • Female lays eggs (not on host)
  • Larvae hatch
  • feeding, moulting on host
  • Nymph
  • Male and female reattach
  • Feeding, mating
  • Female drops off
  • Lays eggs
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18
Q

Describe the life cycle of 2-host ticks

A
  • 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
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19
Q

Describe the life cycle of 3-host ticks

A
  • 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
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20
Q

Where does mating take place?

A

On the host

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21
Q

Describe nidiculous ticks

A
  • In the nest of host
  • When not feeding, tick stays in teh host’s nest/burrow
  • Most Argasid ticks, have multiple nymph stages
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22
Q

Describe non-nidiculous ticks

A
  • 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
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23
Q

Compare hard and soft ticks

A
  • Soft: soft leather bodies, legs hidden under tick, usually on birds
  • Hard: scutum covers whole of back in males
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24
Q

Compare the scutum of male and female hard ticks

A
  • Female hard tick scutum only covers half of body
  • Will cover less as she feeds and swells
  • In male covers whole back
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25
Q

Describe soft ticks

A
  • Argasidae
  • Most are nest parasites
  • Swell when take on blood meal
  • Lots of nymph stages
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26
Q

Describe Argas persicus

A
  • Fowl tick
  • Soft
  • Poultry and wild birds
  • Lead to anaemia, debilitation, loss of production, weight loss, paralysis
  • Red spots where ticks fed
  • transmission of pathogens
27
Q

Give an example of a pathogen transmitted by Argas persicus

A

Borrelia anserina

28
Q

Explain how Argas persicus can be mechanical vectors

A
  • Do not have to moult before feeding

- Feed during night,, drop off host, lie in nest and latch on again at night

29
Q

Describe teh life cycle of Argas persicus

A
  • Females lay eggs several times during lifetime
  • larvae feed on birds for 2-7 days then drop off into nest
  • 2-7 nymphal moults before adult stage
  • Nymphs and adults feed at night for short period, then drop off
  • Feed several times during each life stage
30
Q

Describe the general life cycle of Ixodidae

A
  • Females feed on host, males not so much
  • Male on host for mating
  • Single larval stage, single nymphal stage
  • Larvae feed on small rodent
  • Nymphs feed on larger mammal
  • Adults on large mammals e.g. dogs, humans, deer (but may also be rodent at each stage)
31
Q

Describe questing

A
  • Follow concentrations of CO2 to find hosts
  • Crawl up stems of grass or edges of leaves with front legs exteneded
  • Ready to climb onto passing host
32
Q

Give examples of diseases spread by Ixodid ticks

A
  • Tickborne fever
  • Tick pyraemia
  • Lyme disease
  • Louping ill
  • Babesiosis
  • Theileriosis
33
Q

Describe Tickborne fever

A
  • Anaplasma phagocytophilum (rickettsia)
  • Affects white blood cells
  • Transstadial
  • Wide range of species affected
  • Mostly by Ixodes ricinus
  • cauases fever, immunosuppression, occasional haemorrhagic syndrome (and Human granulocytic Ehrlichiosis in North America)
34
Q

Describe the role of Ixodes trianguliceps in the spread of tickborne fever

A
  • Spreads Anaplasma around rodents

- These then pass it on to Ixodes ricinus

35
Q

Describe tick pyaemia

A
  • In lambs 2-12 weeks old
  • Immunosuppressed by anaplasmosis
  • Staphylococcus aureus introduced through bite wounds, umbilicus etc
  • Leads to abscesses anywhere (liver, lung etc) incl joints
36
Q

What is the causative agent of Lyme disease?

A

Borellia (esp. B. burgdorferi_

37
Q

Describe Lyme disease

A
  • Distinct circular rash “bullseye”
  • Flu like symptoms, tiredness fatigue), muscle pain, joint pain, headaches, high temeprature (fever) chills and neck stiffness
  • More serious symptoms can develop long time later
  • Readily treated with antibiotics
38
Q

How can Borrellia spp. be transmitted within ticks?

A
  • Transtadial

- Transovarial

39
Q

What is Louping ill?

A

Infectious ovine encephalomyelitis

40
Q

Describe Louping ill

A
  • Mainly sheep and grouse
  • Upland areas
  • Closely related to tickborne encephalitis virus
  • Infects CNS
  • Significant suffering
41
Q

Describe control of Louping ill

A
  • Voluntary
  • Use of aaricides
  • Iinactivated vaccine against virus
42
Q

Describe tick to tick transmission of Louping ill

A
  • Via dendritic cells of host
  • Dendritic cells pick up salivary Igs
  • Drawn to neighbouring tick
  • Transmit virus to next tick
43
Q

Describe Babesiosis and Theileriosis

A
  • Similar to protozoans causing malaria and sleeping sickness
  • Parasitise red blood cells of vertebrates
  • Transovarial and transstadial transmission
44
Q

Describe the diseases caused by Theileria

A
  • T. annulata (tropical)
  • T. parva (East Coast Fever)
  • Cattle disease in Africa
  • Found in local bovids, cause little disease
  • Severe disease in domestic cattle
  • lymphadenopathy, fever, haemorrhages, anorexia, collapse, pulmonary oedema, dyspnoea, death
45
Q

Describe the diseases caused by Babesia

A
  • Pyrexia, severe haemolytic anaemia, haemoglobinuria
  • Potentially death of infected animals
  • Commonly known as Red Water Fever in cattle
46
Q

What species of Babesia are spread by Ixodes spp?

A
  • B. divergens (Ixodes ricinus)

- B. microti

47
Q

What species of tick is reponsible for the spread of B. bovis?

A

Rhipicephalus sp

48
Q

What ticks spread B. canis?

A
  • Dermacentor spp.

- Rhipicephalus spp.

49
Q

Outline the key points of Ixodid tick control

A
  • Dips, sprays, pour ons, collars, ear tags etc
  • Long trousers, boots, long sleeved shirts
  • Control of ticks on wildlife and environment not practical
  • Remove tick asap as pathogens transmitted only after feedback for a while
  • vaccination
50
Q

Which tick borne infections can be vaccinated against?

A
  • Lyme disease in dogs

- Louping ill in sheep

51
Q

Which types of tick (soft/hard) can have festoons?

A

Hard

52
Q

Where are the mouth parts located in hard and soft ticks?

A
  • Hard: dorsal

- Soft: ventral

53
Q

What makes ticks hard to manage?

A
  • Not host species restricted
  • Live longer than flies, can starve for many years
  • Good mouth parts with salivary secretions where many components unknown to us
54
Q

How can the larval and nymphal stages of ticks be distinguished from adults?

A
  • Larval: 3 pairs of legs instead of 4, paler scutum

- Nymph: paler and softer scutum, 4 pairs of legs

55
Q

Which genus of ticks have festoons?

A
  • Haemaphysalis
  • Hyalomma
  • Rhipicephalus
  • Dermacentor
  • i.e. hard ticks except ixodes
56
Q

Which genus of ticks have anal groove anterior to anus as opposed to posterior?

A

Ixodes

57
Q

Which genus of tick have triangular pedipalps?

A

Haemaphysalis

58
Q

Which genus’ of tisk have non-triangular pedipalps?

A
  • Ixodes
  • Hyalomma
  • Dermacentor
59
Q

Which genus of ticks have long pedipalps?

A

Hyalomma

60
Q

Which genus’ of ticks have short pedipalps?

A
  • Haemaphysalis
  • Rhipicephlus
  • Dermacentor
61
Q

Which genus of ticks has hexagonal basa capituli?

A

Rhipicephalus

62
Q

Which genus of ticks has rectangular basa capituli?

A

Dermacentor

63
Q

How can larval stages of ticks be distinguished from insects?

A
  • Both have 3 pairs of legs

- However ticks (all arachnids) have 2 body parts, insects have 3