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Parasitology 2 Flashcards

1
Q

Name the juvenile growth hormone analogues

A
  • S-methoprene
  • Pyriproxyfen
  • Dicyclanil
  • Fenoxycarb
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2
Q

What is the mode of action of lufenuron?

A

Chitin synthesis inhibitor

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3
Q

What is the mode of action of cyromazine?

A

Triazine derivative

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4
Q

Describe the use of Insect Growth Regulators

A
  • No adulticidal properties
  • Interrupt environmental stages of flea life cycle but slow to act
  • Important in household flea sprays
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5
Q

Outline the safety of Insect Growth regulators

A
  • Very safe

- Only act at receptors present in insects

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6
Q

Describe the mechanism of action of juvenile hormone analogues

A
  • Mimic activity of juvenile hormone
  • Ovicidal activity
  • Prevents flea larvae developing
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7
Q

Give examples of uses of juvenile hormone analogues

A
  • Spot-ons e.g. frontline combo (combination with adulticide)
  • Environmental sprays e.g. indorex
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8
Q

Explain the mechanism of action of chitin synthesis inhibitors

A

Prevent normal developing of the exoskeleton, thus stopping larvae developing

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9
Q

Give examples of and use of ectoparasite repellants

A
  • Pyrethrins/pyrethroids
  • Diethyltoluamide (DEET)
  • Citronella
  • Repel flying insects
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10
Q

Give an example of and use of dessicants for ectoparasites

A
  • Sodium polyborate

- Used in environment e.g. carpet powders

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11
Q

Give an example of and use of synergists

A
  • Piperonyl butoxide
  • Inhibits insect detoxification pathways and increases available concentration of insecticides
  • Used especially with pyrethrins to reduce insecticide content
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12
Q

Outline the use of lime sulphur dip

A
  • Traditional pesticide used especially in cats for control of Demodex cati, Cheyletiella, lice
  • Also fungicidal and bactericidal
  • Unpleasant odour, may stain light coats, must prevent ingestion
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13
Q

Give examples of topical preparations of ectoparasite drugs

A
  • Spray
  • Dip
  • Powder
  • Spot-on
  • Pour-on
  • Collar
  • Ear tag
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14
Q

Give examples of systemic preparations of ectoparasite drugs

A
  • Injectable
  • Oral
  • Topically applied
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15
Q

What is a benefit of spot on preparations?

A

Good compliance

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16
Q

What are some disadvantages of spot-on preparations?

A
  • Human toxicity immediately after application (esp. children)
  • Ingestion of product
  • Occasional skin lesions at site of application
  • Wetting/bathing may compromise action
  • Concentration gradient with distance from site of application if not absorbed systemically
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17
Q

What are some disadvantages of dips and sprays?

A
  • Operator exposure
  • Dips will be depleted of chemical with use, so need to top up between animals
  • Care regarding appropriate storage and disposal (environmental contamination/pollution)
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18
Q

What are some disadvantages of collars for ectoparasite control?

A
  • Remove during swimming/washing to avoid depletion of drug from collar and contamination of aquatic life
  • Occasional contact irritation
  • Care to prevent animal chewing/swallowing collar
  • Use immediately once opened
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19
Q

What is the significance of duration of action?

A

Shorter duration of action will require more frequent application, which may reduce compliance and increase risk of infection

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20
Q

Outline reasons for lack of efficacy of anti-ectoparasitic drug

A
  • Resistance may occur, but usually other factors account for lack of efficacy
  • Inappropriate frequency/dosing
  • Incorrect administration
  • Depletion due to bathing/wetting
  • Failure to control re-infestation from other animals/environment
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21
Q

Give examples of how anti-ectoparasitic drugs may lead to environmental effects

A
  • Sheep dip disposal can contaminate waterways

- Insecticidal material in dung may affect dung beetle and flies

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22
Q

In what species is the use of fipronil contraindicated?

A

Rabbits (fatalities)

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23
Q

In what species is pyrethrin and pyrethroid use contraindicated?

A
  • Cats

- Pyrethroids contraindicated in fish and birds

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24
Q

In what animals are macrocyclic lactones contraindicated? Explain

A
  • Collies/herding breeds
  • More likely to have MDR1 gene (multi-drug resistance), encodes for P-glycoprotein
  • Responsible for pumping drugs out o the CNS
  • Where there is a mutation in MDR1, drug crosses the BBB and leads to neurological signs/death
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25
Q

In what animals is spinosad contraindicated?

A

Dogs with epilepsy

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26
Q

In what scenario is use of Advocate contraindicated and why?

A
  • Advocate contains moxidectin/imidacloprid

- Canot be used with any other macrolyclic lactone e.g. Milbemax (milbemycin and praziquantel)

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27
Q

In what scenario is amitraz use contraindicated?

A
  • Should not be applied by people taking monoamine oxidase inhibitors (anti-depressants) or with diabetes mellitus
  • Not to be used concurrently with alpha-2 adrenergic agonists e.g. medetomidine
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28
Q

Outline physical methods of ectoparasite control

A
  • Conditions unsuitable for parasite to live/reproduce in, or avoid contact with parasite
  • removal of dung, moist bedding, straw, food waste
  • Minimise pasture worm burdens, tail docking, dagging (reduces myiasis of sheep)
  • Barriers (e.g. fly masks) useful where parasite only spends part of life on host and are harder to control (prevent irritation /infection)
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29
Q

Outline biological control methods for ectoparasites

A
  • Using organisms that are predators, competitors or pathogens of parasites
  • Best for those that live or reproduce in the environment
  • e.g. parasitoid wasps
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30
Q

Explain the use of trapping and monitoring in the control of ectoparasites

A
  • Can be used to protect (usually enclosed) environments such as stables or milk parlours
  • Useful indicator of when additional measures e.g. chemical treatment may be needed
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31
Q

Explain the use of modelling and forecasting in the control of ectoparasites

A
  • Predict seasonal patterns of particular ectoparasites
  • Helps vets/farmers to integrate chemical and non-chemical control techniques and use ectoparasciticides prophylactically
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32
Q

Give examples of natural botanical products that have been suggested in ectoparasite control

A
  • Citronella
  • Cedarwood
  • Lemongrass
  • Rosemary
  • Sesame
  • Lavender
  • Tea-tree
  • Eucalyptus
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33
Q

What is a disadvantage of using natural botanical products in ectoparasite control?

A

Little safety and efficacy testing (use of several products with similar active ingredients or interacting agents may lead to toxicity to pet)

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34
Q

Give the life cycle of the flea

A
  • Adult on host
  • Eggs laid
  • Hatch in environment
  • Larvae form pupae in environment
  • Can stay in environment for long periods of time
  • Adults jump onto host
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35
Q

List the flea adulticides

A
  • Imidacloprid
  • Fipronil
  • Spinosad
  • Pyriprole
  • Metaflumizone
  • Selamectin
  • Indoxacarb
  • Isoxazolines
  • Nitenpyram (short action)
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36
Q

List the flea larvicidals

A
  • Imidacloprid
  • Indoxacarb
  • Selamectin
  • S-methoprene (IGR)
  • Lufenuron (IGR)
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37
Q

List the flea ovicidals

A
  • Spinosad
  • Selamectin
  • S-methoprene (IGR)
  • Lufenuron (IGR)
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38
Q

List products that are effective at treating lice

A
  • Topical organophosphates
  • Pyrethroids
  • Topical avermectins
  • Ivermectin injection (sucking lice)
  • Amitraz (cattle and pigs)
  • Imidacloprid, fipronil (dogs, cats)
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39
Q

Describe the control of lice

A
  • Killed by most routine flea treatments
  • Heavy infestations associated with unsanitary conditions so attend to environment
  • Basic hygiene is sufficient
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40
Q

Outline methods of control of blood feeding flies

A
  • Fly avoidance
  • Repellants
  • Topical insecticides e.g. organophosphates, pyrethrins/pyrethroids
  • Barriers
  • Insecticidal treatment of environment
  • Control of breeding sites
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41
Q

Outline the control of nuisance flies

A
  • Topical organophosphates
  • Pyrethroids
  • E.g. ear tags
42
Q

What are the direct effects of tick infection?

A
  • Blood loss
  • Local cutaneous damage and inflammation
  • Secondary skin infection
  • Production loss
43
Q

What are the indirect effects of tick infection?

A

Vectors of disease

44
Q

What diseases are transmitted by Ixodes ricinus?

A
  • Borrelia burgdorferi
  • Louping ill virus
  • Ehrlichia
  • Anaplasma
  • Babesia in cattle
45
Q

What diseases are transmitted by Haemophysalis punctata and where is this tick found?

A
  • S England and Wales, widely in Europe

- Babesia gibsoni

46
Q

What diseases are transmitted by Dermacentor reticulatus and where is this tick found?

A
  • West Europe, rarely UK

- Babesia canis

47
Q

What diseases are transmitted by Rhipicephalus sanguineus and where is this tick found?

A
  • S Europe, cannot survive outside of temperate climates (may be found in warm kennels)
  • Babesia canis, Babesia vogeli, Ehrlichia canis, Rickettsia, Anaplasma
48
Q

Describe louping ill

A
  • Infectious ovine encephalomyelitis
  • Mainly causes disease in sheep and grouse in upland areas
  • Occasionally infects humans and other animals
  • Attacks CNS, significant suffering of animal
49
Q

Outline the control of Louping ill

A
  • No statutory control measures
  • Control is voluntary
  • Use of acaricides
  • Inactivated vaccine against virus
50
Q

What is babesiosis caused by?

A

Babesia spp are intraerythrocytic protozoan parasites

51
Q

Outline infection with Babesia

A
  • Destruction of erythrocytes causing severe anaemia (haematuria may be seen)
  • canine cases range from a hyperacute, shock-associated, haemolytic crisis to subclinical infections
  • Signs: fever, inappetance, weight loss, mucus membrane pallor, lethargy, jaundice, splenomegaly, lymphadenopathy, haemolytic anaemia, haemoglobinuria
  • Severe cases lead to acute collapse, multiple organ failure, death
52
Q

What are the aims of tick control?

A
  • Prevent attachment

- Prevent transmission of pathogens by prompt killing/removal

53
Q

What are the strategies of tick control?

A
  • Avoid tick habitats and local tick “hot spots” during late spring and summer
  • Destruction of tick habitats and spraying environmental pesticides
  • Daily inspection of haircoat, prompt removal of ticks, careful disposal
  • Repellent or acaricide with rapid knockdown effect
54
Q

Describe the method of tick removal

A
  • Tweezers/specials tools, avoid handling with uncovered fingers
  • Place instruments around area where mouthparts enter skin
  • Slow, steady motion to pull tick away from skin
  • Do not damage tick and ensure mouthparts are removed
  • Place in sealed container, disinfect area around bite
55
Q

What factors affect acaricide selection?

A
  • Likely species of tick
  • Required duration of action
  • Likelihood of swimming/bathing
  • Risk of adverse effects (species specific)
  • Potential for drug interactions
  • Accidental contact
56
Q

Name the groups of tick control drugs

A
  • Isoxalzolines
  • Pyrethroids
  • Phenylpyrnazoles
57
Q

Which isoxazolines are licensed for cats?

A

Flurolaner and sarolaner

58
Q

Name the isoxazolines used for ticks, their duration of action, application and the species they are licensed for

A
  • Aloxolaner, tablet: 4 weeks, dogs
  • Flurolaner, tablet for dog, spot on for dogs and cats: 8-12 weeks
  • Lotilaner, tablet: 4 weeks, dogs
  • Sarolaner: 4 weeks, spot on for cats, tablet for dogs
59
Q

Name the pyrethroids used for ticks, their duration of action, application and the species they are licensed for

A
  • Deltamethrin, collar: 20-24 weeks, dogs
  • Flumethrin, collar: 32 weeks, dogs and cats
  • Permethrin (imidacloprid) spot on: 3-4 weeks, dogs
  • Permethrin (dinotefuncin, pyriproxyfen) spot on: 3-4 weeks, dogs
60
Q

Name the phenylpyrrazoles used for ticks, their duration of action, application and species they are licensed for

A
  • Pyriprole: spot on, 4 weeks, dog
  • Fipronil: spot on, spray, 4 weeks, dog and cat
  • S-methoprene (fipronil): spot on, dog 4 weeks, cat 2 weeks
  • Firpronil and amitraz: 5 weeks, spot on, dogs
61
Q

Outline the control of ixodid ticks in cattle and sheep

A
  • Prolonged treatment
  • Acaricides topically (dips, spray, shower, spot-on, slow release ear tap of OPs)
  • OPs, pyrethroids, amitraz
  • Macrocyclic lactones parenterally
  • Weekly in tick season
  • Removal of stock from infected pasture
62
Q

Describe the direct effects of mites

A
  • Cutaneous lesions (mange)
  • Loss of blood or other tissue fluids
  • Immunopathological response
  • Zoonotic
63
Q

Describe the indirect effects of mites

A
  • Secondary bacterial infections

- Transmit pathogens

64
Q

Describe mange

A
  • Infestation by mites (acariasis)
  • Severe dermatitis
  • Erythema, pruritus, scale formation, lichenification, crust formation, alopecia
  • Significant welfare problems, economic losses
65
Q

Describe the mite life cycle

A
  • Hatch from eggs, 6 legs
  • Larva moult to become 8 legged nymph
  • 1-2 nymphal stages
  • Nymph moult to become adult
  • Adult female lays eggs
66
Q

Outline how mite life cycle affects treatment

A
  • Some only on host to feed (e.g. Dermanyssus gallinae) and so are difficult to treat
  • Need to treat environment
67
Q

Describe canine sarcoptic mange

A
  • Affects large number of mammalian species
  • Strains usually host adapted, but can be zoonotic
  • Highly contagious, reservoir in foxes
  • Can survive off host for 2-3 weeks
68
Q

Describe the actions against sarcoptic mange

A
  • Treat affected animals
  • Treat all in contacts
  • Treat environment
  • Drugs for pruritus and secondary infection
  • Advise owner re zoonotic risk
  • Isolate affected animals
  • Prevent future infestation (avoid fox contact, routine use of scabicidal product)
69
Q

Name the drug options for treatment of sarcoptic mange in dogs

A
  • Moxidectin
  • Selamectin
  • Sarolaner
  • Amitraz
70
Q

Outline the use of moxidectin in dogs as a sarcoptic mange treatment

A
  • Monthly application for 2 doses

- Also active vs fleas, selected other ectoparasites and endoparasites

71
Q

Outline the use of selamectin in dogs as a sarcoptic mange treatment

A
  • Monthly appplication for 2 doses

- Also active vs fleas, selected other ecto and endoparasites

72
Q

Outline the use of sarolaner in dogs as a sarcoptic mange treatment

A
  • Monthly tablet for 2 doses
  • Also licensed for fleas, ticks, Demodex, Otodectes in dogs
  • Only isoxazylene licensed for sarcoptic mange
73
Q

Outline the use of amitraz in dogs as a treatment for sarcoptic mange

A
  • Weekly baths
  • Very effective but more time consuming treatment
  • Side effects to animals/people, physically more demanding
74
Q

Describe canine demodectic mange

A
  • Present in small numbers as a commensal
  • Clinical disease associated with reduced immuno-competence
  • Juvenile onset, likely to resolve spontaneously with age
  • Do not treat if mild-localised, only if generalised
  • Not contagious, no environmental involvement
75
Q

Outline sheep scab

A
  • P. ovis causes sheep scab
  • Economic importance
  • Reportable in many countries
76
Q

Outline the control of sheep scab

A
  • Establish source
  • Review quarantine procedures
  • Contact neighbours to warn
  • Check shared fences for gaps/common rubbing areas, consider double fencing
  • Treat sheep with dip or injection
77
Q

Outline the epidemiology of coccidiosis in chickens and farm animals

A
  • Transmission via contaminated water and food
  • Young age of host (esp. where insufficient colostrum)
  • Endemic stability of Coccidia
  • Overcrowding
  • Higher prevalence in spring due to higher prevalence of other endoparasites at this time
78
Q

Describe the clinical presentation of coccidiosis in chickens

A
  • Loss of appetite and emaciation
  • Anaemia, weakness
  • Diarrhoea, weight loss
  • Death
79
Q

Explain how Eimeria causes its clinical signs

A
  • Damage to superficial layer of GIT
  • Destroys blood vessels leading to haemorrhage
  • Anaemia as a consequence
  • Malabsorption therefore weight loss and diarrhoea
80
Q

Describe the characteristic post mortem finding of Eimeria tenella in chickens

A

Haemorrhage in the caeca

81
Q

Describe the characteristic post mortem finding of Eimeria in rabbits

A

Enlarged liver with multi-focal greyish white coalescing lesions/nodules and yellowish liquid caseous pus

82
Q

Describe the clinical signs of coccidiosis in calves

A
  • Diarrhoea, may be haemorrhagic

- Weight loss and reduced weight gain

83
Q

Describe the life cycle of Eimeria

A
  • Sporulated oocyst ingested by animal from environment
  • Excysts (due to stomach acid)
  • Sporozoites released, invades host cell, begins to grow (schizogony)
  • Schizont produced, contains merozoites, ruptures, merozoites release
  • Merozoites invade host cells, repeat asexual reproduction phase
  • 2nd gen merozoites sexually reproduce following meront rupture
  • Type 2 merozoites invade host cells, either form macrogametocyte (F) or microgamont (M)
  • MIcrogametocytes released from cell, fuse with macrogamont, form zygote (oocyst)
  • Oocyst exits cell and excreted
  • Oocyst sporulates to become infective
84
Q

Name the most common Eimeria species causing coccidiosis in chickens

A
  • E. acervulina
  • E. nectriz
  • E. tenella
85
Q

Describe the location and pathogenicity of E. acervulina

A
  • Mostly duodenum
  • Mild disease
  • Upper SI
  • Older chickens
  • Leads to egg production drop in layers
86
Q

Describe the location and pathogenicity of E. necatrix

A
  • Mid-small intestine
  • Severe disease
  • Bloody diarrhoea, death
87
Q

Describe the location and pathogenicity of E.. tenella

A
  • Only caecum involved
  • Severe disease
  • especially chicksn less than 6mos old
88
Q

Which Eimeria species are primarily responsible for coccidiosis in cattle?

A
  • Eimeria bovis

- Eimeria zuernii

89
Q

What does the finding of Eimeria oocyts in cattle faeces indicate?

A
  • Infection

- Even without clinical disease, may be due to variable susceptibility but reasons largely unknown

90
Q

Describe the frequency, morbidity, mortality and presence of symptoms of sub-clinical coccidiosis in cattle

A
  • High frequency in adults
  • High morbidity
  • Low mortality
  • Symptoms usually absent
91
Q

Describe the frequency, morbidity, mortality and presence of symptoms of clinical/overt coccidiosis in cattle

A
  • Low frequency in adults
  • High morbidity
  • High mortality
  • Symptoms usually present
92
Q

Outline the methods of diagnosis of coccidiosis in cattle

A
  • Clinical diagnosis not very specific
  • Pathology: very specific but time consuming
  • Laboratory diagnosis: metabolic parameters, faecal smears and flotation, McMaster method, PCR, serology
93
Q

Describe the pathological lesion scoring of coccidiosis in cattle

A
  • Score intestinal lesions 0-4
  • 0: no lesion
  • 1: very mild lesion
  • 2: mild lesion
  • 3: quite severe damage
  • 4: severe damage to the intestines
94
Q

Outline the impact of subclinical coccidiosis

A
  • Significant economic impact
  • Treatment expensive
  • Production loss due to reduced growth, high morbidity/mortality, egg production drop
  • Condemnation of emaciated carcasses
95
Q

Outline problems in the management of coccidiosis

A
  • Food residues of coccidiostats
  • Lasalocid (ionophore group, most common to use) residues in eggs
  • Could have adverse effects on health of humans, potent cardiovascular properties
96
Q

Outline the treatment of coccidiosis

A
  • Usually self-limiting, immunity develops rapidly, maintained by continuous exposure
  • Treated animals protected for weeks
  • Careful management of young, and to prevent exposure in older animals
  • Limit risk of introduction of infected animals into herd
97
Q

What are the aims of metaphylactic treatment against coccidiosis?

A
  • Prevent disease
  • Prevent production losses
  • Reduce contamination and thus infection pressure
  • Maintenance of productivity
  • Target early/various life cycle stages
98
Q

Outline the principles of the treatment of subclinical coccidiosis

A
  • Widespread subclinical coccidiosis will require aggressive control programs and many years
  • Practical control programme and sound management
  • Aims to eliminate disease and reduce economic impact of subclinical disease
99
Q

From what age onwards can coccidiosis occur in calves and why?

A

Will not occur before 18 days old as the animal is still suckling and the life cycle takes ~3 weeks
(there is no vertical transmission, must be contaminated feed/water)

100
Q

List the drugs licensed for prevention/treatment of blowfly strike in sheep and give the group they belong to

A
  • Alpha-cypermethrin, cypermethrin and deltamethrin: pyrethroids
  • Diazinon (dimpylate): organophosphate
  • Cyromazine and dicyclanil: IGRs

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