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Year 2 Parasitology > Ectoparasites (See Old App For Images) > Flashcards

Ectoparasites (See Old App For Images) Flashcards

1
Q

What are Arthropoda

A

Invertebrates
external waterproof skeleton made of chitin
Segmented body
Jointed limbs
Haemocoel= body cavity containing haemolymph

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2
Q

Are arthropods of vet importance permeant or temp parasites?

A

Can be both

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3
Q

How would you split arthropods

Give examples of what’s in each category

A

Insects- flies, lice, fleas

Arachnids- ticks and mites

Crustceans

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4
Q

List economic losses and welfare issues associated with ecto parasites

A 
Skin damage/invasion e.g. Sheep scab and myiasis (fly strike)
Nuisance flies- decline in milk 
Self wounding secondary infections
Inflammation/pruritis (sarcoptic mange)
Toxic and allergic reactions (FAD)
Blood loss
Pathogen transmission
Cost of treatment/control
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5
Q

What are tsetse flies a vector for?

A

Trypanosomes (in Africa)

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6
Q

How do ectoparasites grow?

A

By ecdysis/shedding under the influence of juvenile hormones

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7
Q

How many legs in:

Adult insect

Adult/nymph stage arachnid

Larval stage arachnid

A

3 pairs

4 pairs

3 pairs

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8
Q

The exoskeleton provides protection and support. What else do it have on it?

A

Hairs/bristles/spines etc.

It’s divided into plates called sclerites

Muscles are attached to the inside of it

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9
Q

What does the nervous system consist of?

A 
Ganglia (brain)
Sensory organs (e.g. Eye)
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10
Q

How do they perform respiration

A

Via openings in the protective cuticle

Spiracles in insects/stigmata in ticks and mites

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11
Q

What does the GI tract consist of?

A

It’s a simple tube from mouth to anus

Feeding mouthparts- foregut/proventr (food broken up)- midgut (store and digest) - malpighian tubules (where waste from haemocoeal filters into gut) - hindgut (water absorption)

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12
Q

How many body regions in insects

Which do the legs come from

Do they have wings? Antennae? Specialised mouthparts?

A

3- head, thorax, abdomen

Legs from thorax

Can have wings, have 2 antennae and have specialised mouth parts

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13
Q

How many body segments in arachnid

Do they have wings/antennae?

A

2 - cephalothorax and abdomen

No

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14
Q

Do both insects and arachnids have specialised mouthparts e.g. Pool feeders and sponging mouthparts?

A

Yes

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15
Q

What are the two types of life cycle in ectoparasites- which undergoes each??

A

Holometabolous- complete metamorphosis = flies

Hemimetabolous - incomplete metamorphosis- lice and ticks

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16
Q

Explain the differences with these life cycles

A

Holo e.g. Insects have 4 stages. Egg, larvae, pupae, adult. Wings develop inside body

Hemi e.f. Ticks have 3 stages, egg, nymph, adult

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17
Q

How do ticks reproduce?

A

Via a spermatophore- a capsule surrounding a mass of spermatozoa produced by the male in various animal species and transferred to the female

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18
Q

How do flies reproduce

A

Females must obtain protein to mature their eggs. This is why they pester cattle and why Mosquitos suck blood

The female is fertilised and then lays her eggs

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19
Q

What does the order Diptera mean?

A

Insects

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20
Q

What is the difference between ticks and mites?

A

Ticks possess a toothed hypostome

Mites do not

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21
Q

What kind of feeder are ticks

Why are they so important

A

They are obligate blood feeders

They are important as disease vectors

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22
Q

What do mites feed on? E.g. Sarcoptes

What do they cause?

A

Skin scales, lymph exudate and fluid

Mange

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23
Q

Give an example of a non burrowing mite

A

Psoroptes ovis (sheep scab)

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24
Q

Give an example of a follicle dwelling mite

A

Demodex spp.

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25
Q

What sort of things have caused ectoparasites to be a modern growing problem that need controlling?

A 
Intensification of animal husbandry
High livestock densities
Global transport of humans and animals
Artifical selection towards greater susept to infest
Modern home environments
Growing reservoirs e.g. Protected deer
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26
Q

Why do we need to control ectoparasites?

A 
They cause ...
profit loss
Ill health
Poor condition/weight loss/irritation/dermatitis 
Hide and fleece damage
Transmit disease
Vectors for zoonotic disease
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27
Q

What are seasonal trends seen in ectoparasites?

A

Nuisance flies are a summer issue, they develop in the environment. Flies cause fly strike in late spring/early summer. Ticks are also a summer issue- there numbers are greatest in May/June

Fleas are an issue all year round but mainly summer

Lice and mites are a winter problem

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28
Q

What are the approaches to control?

A

Chemical control ‘on host’ dominated by insecticides/acaricide

Several “off host” approaches e.g. Sprays/traps

Integrated pest management is a combo of chemical control on and off host. Combining insecticide use with environmental control. Non chemical uses also e.g. Ensuring hygiene of fomites, reduction of exposure e.g. House animals or quarantine (chemical, environmental, fomites,quarantine)

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29
Q

What are basic preparations?

What advances are there for targeted control?

What special considerations must be taken into account?

A

Chemical/non chemical/environment/topically/systemically

Advances: pour on/spot on/collars/ear tags

Can give orally, parentally or topically

Need to bare in mind environmental or contamination toxicity and also safety margins and meat withdrawal periods

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30
Q

Name the major classes of ectoparasitacides

A 
Organochlorines
Organophosphates
Synthetic pyrethroids
Macrocyclic lactones
Insect growth regulators
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31
Q

What was the big issue with organochlorines?

A

Led to widespread resistance in Mosquitos

Went into the food chain via birds and had a bad environmental impact

Hence banned in 1984

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32
Q

How do organophosphates work?

Why are they relatively toxic to humans?

A

They mimic ACh, leading to accum of insect neurotransmitter, cause paralysis and death

Because they are so lipid soluble

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33
Q

Give an example of a organophosphate still used today??

A

Diazinon

Used as sheep dip to control mites/lice/blowfly for at least 60 days

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34
Q

What is permethrin cypermethrin??

How does it work?

List some qualities it has

A

It’s a synthetic pyrethroid

It works by exciting cell membranes, causing depolarisation and paralysis

Photostable, high potency, broad spec, many preparations, effective against flies/lice/ticks

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35
Q

Name the 2 broad types of ML??

Give an example of each

A

Avermectins e.g. Ivermectin

Milbemycins e.g. Milbemycin oxime

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36
Q

What do MLs do?

What are they effective against?

A

Inc GABA binding, inc CL into cell, cause hyperpolarisation and flaccid paralysis

Wide range of arthropods and nematodes

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37
Q

Why do MLs not effect mammals?

A

GABA neuro transmission is only in CNS in mammals.

The large ivermectin molecules does not readily cross blood brain barrier

38
Q

What other good qualities do MLs have?

What do we need to bear in mind?

A

They are highly lipophilic, so are stored in fat, slow released and persistent and therefore provide extended protection (longer when give IV or sc)

Withdrawal periods, oral admin very little effect against mites which cause sheep scab

39
Q

Which breed must you never give ivermectin to?

A

Collies

Genetic mutation meaning it can cause BBB and lead to CNS symptoms

40
Q

What are insect growth regulators used for?

What do they do?

A

Immature stages (used for blowfly larvae and flea control)

They can be chitin inhibitors so prevent chitin/exoskeleton development. Or they can be juvenile hormone analogues and so again prevent growth

41
Q

Give an example of a chitin inhibitor

A

Diflubenzuron

42
Q

Give an example of a juvenile hormone analogue

A

Methoprene

43
Q

Give trade names for these (may help remember what effective against)

Imidacloprid
Fipronil
Amitraz
Afoxolaner 
Fluralaner
A 
Advantage
Frontline
Alludex
Nexguard
Bravecto
44
Q

What does imidacloprid do?

What does it target?

Bad points?

A

Binds to nAch receptors leads to paralysis and death

Adult fleas only

High bird toxicity/neg impact in bee pop

45
Q

What does fipronil do?

What’s it effective against?

Bad points?

A

Blocks GABA transmission. Lipophilic so diffuses into Seb glands acts as reservoir

Fleas and ticks

Long redid activity, toxic to fish and bees

46
Q

What does amitraz target?

A

Ticks and mites

47
Q

Which animals can you not use amitraz in?

A

Horses and cats

48
Q

What do afoxalaner and Fluralaner treat for

A

Ticks fleas

Also Demodex??

49
Q

What do the flies in the muscidae family feed on?

A

Secretions or suck blood

50
Q

What’s myiasis

A

When flies lay eggs on animals and larvae invade and feed on tissue (fly strike)

51
Q

Whic muscidae fly is biting? Which is strange for this family

A

Stomoxys calcitrans (the stable fly)

52
Q

Why is this fly important

A

When it heavily infests cattle it lowers milk production
Bites humans.
In some parts of the world it is a vector for trypanosomid parasites.

53
Q

Describe the life cycle of a muscidae fly

A

Complete metamorp with 4 stages

Over winters in larval/pupae stage under manure piles

Summer conditions optimum for development. Completes life cycle in 7-10 days.

Dispersed to other livestock in pasture

54
Q

Where do flies rest and mate

A

Warm sun exposed surfaces eg gates etc.

55
Q

Where do flies prefer to feed in the animal?

A

Lower parts especially legs and flank

56
Q

Give some host responses to this

A

Stamping feet
Shivering of skin
Sudden turning of head
Tail swishing

57
Q

Stomoxys calcitrans causes what problems?

A

Fly worry

Pathogen transmission - equine infectious anaemia, trypanosomes, and others such as anthrax and BVD Aare suspected

58
Q

Name 3 non biting muscidae

A

Head fly, face fly and house fly

Hydrotaea irritans, Musca autumnalis, Musca domestica

59
Q

What does hydrotaea irritans pester

A

Cattle, sheep, horses and man

60
Q

Where does the headfly deposit eggs?

How many generations of flies do you get each year.

A

Pasture soil

Only 1

61
Q

State some behaviours of the headfly

A

Doesn’t enter buildings

Found around livestock and us

Typically on wooded pasture

Most numerous on overcast, warm, humid days in August

62
Q

State some host behaviours in response to the headfly

A

Rapid head turn

Tail swishing

63
Q

Hydrotaea irritans congregates around the corner of eyes and around ends of udder tears, why is this a problem

A

Transmits agents of summer mastitis

Fly worry but not as dramatic as biting spp

64
Q

Whic livestock does Musca autumnalis mostly effect

A

Cattle and horses

Found on face muzzle and eyes (hence name face fly)

65
Q

Key points for the lifecycle of the face fly

A

Don’t enter buildings
Develop in dung, hatch quickly, larvae feed on microbes in faeces, emerge (temp dependent)
Populations build up in autumn

66
Q

What diseases is the face fly associated with?

A

Pink eye in cattle: infectious bovine keratoconjunctivitis caused by moraxella bovis

Likely to cause similar in horses

Also vector of thelazia (eye worms) and habronema (stomach worms)

67
Q

What’s the main significance of them in the UK though

A

Nusicance

68
Q

Where is the face fly found most?

A

Southern England not northern

69
Q

What tumours are flies thought to be vectors for?

A

Sarcoids

70
Q

Name 2 biting fly NOT in the family muscidae of vet importance

A

Tabanus and haematopota

These are both ‘tabanids’

71
Q

Where do tabanids breed?

A

Wet pasture, marshy land next to lakes/ponds

72
Q

What are the significance of tabanids??

A 
They gad (move around most) on sunny days in July and August. They take several small meals. 
Vectors for EIA, anthrax, trypanosomes and bovine anaplamosis (blood parasite)
73
Q

What are culicoides

A

Biting midges

74
Q

Life cycle of biting midges…

A

Dig a hole and feed on free blood

Eggs laid in damp compost heals, decaying veg, and marshy land

Egg to adult in less than 3 weeks

1-2 generations a year

75
Q

What’s the significance of biting midges?

A

Irritation

Cause sweet itch in the UK

Also cause seasonal recurrent allergic dermatitis = a pruritic hypersens reaction to saliva

Cause animals to have self inflicted lesions

76
Q

What pathogens do biting midges transmit

A

African horse sickness

Blue tongue

Schmallenberg virus

77
Q

What genus is the virus African horse sickness in?

A

Orbivirus

78
Q

Simulium spp are black flies. State their life cycle

A

Lay eggs on stones in running water
Aquatic larvae
Adults active most in morning and evening
Live up to 4 weeks feeding on horses and cattle

79
Q

What diseases are back fly associated with?

A

Leucocytozoon to ducks/geese

Non pathogenic onchocerca spp = horses and cattle (roundworm)

Greatest importance in west America and South America where they cause human onchocerciasis (river blindness)

80
Q

How are flies controlled on liveries and farms

A

Integrated pest management approach

Use of insecticides (mainly synthetic pyrethroids) as ear tags, pour one and sprays

Treatment of resting surfaces

Habitat and husbandry management: dung is moved from inside housing, but need to bear in mind population dispersal if used as fertiliser.

Barrier methods: head masks and body protection on horses

81
Q

What fly is a highly adapted parasite of horses?

A

Gasterophilus (the horse bot fly)

82
Q

What does the horse bot fly cause?

A

Myiasis (fly strike)

83
Q

Name 3 species of horse bot fly

When are these most active?

A

G. Intestinalis
G. Nasalis
G. Haemorrhoidalis

Late summer

84
Q

Describe the life cycle of a horse bot fly g.intestinalis

A

Eggs laid late summer on inner forelimbs, hocks and shoulders

Burrow into tongue, moults and exits.

It then goes to the pharynx which can take 3-4 weeks, where it moults to L2

They then cluster in the oesphageal portion of the stomach

They moult to L3 and remain in the stomach until spring when they are passed during faeces in June

85
Q

How many generations of bot fly in 1 year?

A

1

86
Q

Nasalis and haem. Are of lesser importance, where do these ones migrate to?

A

Pyloric part of stomach

Attach to rectum

87
Q

Do bot flies cause disease?

A

Surprisingly only occasionally.

Can form crater like ulcers, inflammation and large maggots are seen in faeces which freaks out owners

88
Q

How do you diagnose bot fly?

A

See larvae in faeces in spring

Eggs on coat in summer

89
Q

How do you treat bot fly?

A

Remove eggs

Anthelmintics (moxidectin = ML)

90
Q

Which part of the arthropod section are mites in?

A

Arachnids

91
Q

Define mange

A

A skin disease caused by parasitic mites characterised by itching, hair loss and formation of scabs and lesions

92
Q

Can non burrowing and burrowing mites cause mange?

A

Yes

Year 2 Parasitology (1 decks)

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