PARASITOLOGY - Ectoparasites Flashcards
1
Q
Which class of ectoparasites incorporates flies?
A
Insecta
2
Q
What is the main order of flies that is of veterinary importance?
A
Diptera
3
Q
What is ‘fly worry’?
A
Animals become distressed by the presence of flies swarming around their heads and eyes, causing them to eat less leading to weight and economic loss
4
Q
What are the three main species of non-biting flies that are of veterinary importance?
A
Musca domestica (house fly)
Musca autumnalis (face fly)
Hydrotaea irritans (head fly)
5
Q
What is the main distinguishing feature of Musca domestica (house fly)?
A
Four longitudinal lines along the thorax
6
Q
How are the legs of non-biting flies adapted for latching onto surfaces?
A
Non-biting flies have tarsal claws and pulvilli which allow them to latch onto surfaces
7
Q
How are the mouthparts of non-biting flies adapted for feeding?
A
Non-biting flies have sponge-like suction pads that allow for the absorption of liquid food as well as prestomal teeth which act as a rasping device to extend existing wounds
8
Q
What do Musca autumnalis (face flies) feed on?
A
Facial secretions such as saliva, tears and mucous as well as open wounds
9
Q
What do Hydrotaea irritans (head flies) feed on?
A
Hydrotaea irritans (head flies) congregate around the heads of livestock causing them to and scratch, rub and bite leading to open wounds which the flies will feed on and extend
10
Q
Give an example of a disease where Musca flies act as a vector
A
Summer sores
11
Q
Which nematode causes summer sores?
A
Habronema nematodes
12
Q
Describe the lifecycle of Habronema nematodes which cause summer sores in horses
A
- Horse expels Habronema eggs in their faeces
- Musca flies lay eggs in the faeces
- Musca larvae ingest the Habronema eggs within the faeces
- Habronema larvae develop within the Musca larvae
- L3 Habronema larvae migrate to the mouthpieces of the Musca fly and the L3 larvae are deposited on the horse when the Musca fly is feeding on facial secretions
- L3 are ingested by the horse and migrate to the stomach where they develop into adults and lay their eggs –>
13
Q
What is the term used to describe the synchronised development between the Habronema and Musca larvae?
A
Transstadial transmission
14
Q
What happens to horses if the Habronema L3 larvae are not ingested and instead remain cutaneously deposited?
A
If the L3 larvae are cutaneously deposited inside an existing wound, this can cause a hypersensitivity reaction causing lesions known as ‘summer sores’
15
Q
What are two species of biting fly that are of veterinary importance?
A
Culicoides (midges)
Melophagus ovinus (sheep ked)
16
Q
(T/F) Male culicoides (midges) feed on blood meals but the females do not
A
FALSE. Female culicoides (midges) feed on blood meals as their require the protein for egg development
17
Q
What is a common disease seen in horses that is caused by culicoides (midges)?
A
Sweet itch
18
Q
During which months of the year is sweet itch most prevalent?
A
Sweet itch is a seasonal disease most common between April to September
19
Q
Which nematode is transmitted by culicoides (midges) as a vector?
A
Onchocerca cervicalis
20
Q
Describe the lifecycle of Onchocerca cervicalis seen in horses
A
- Microfilaria are ingested by culicoides during a blood meal
- Microfilaria develop into L3 larvae within the culicoides
- Culicoides deposit the L3 larvae within the host during another blood meal
- L3 larvae migrate to the nuchal ligament of the horse where they develop into adults and produce more microfilaria
- Microfilaria migrate to the skin and eyes of the horse where they can cause dermatitis –>
21
Q
Name a virus that is transmitted by culicoides (midges)
A
Schmallenburg virus (SBV)
22
Q
How does the Schmallenburg virus (SBV) affect adult animals compared to pregnant animals?
A
Adults animals exhibit transient clinical signs however trans-placental transmission can cause abortion or severe congenital malformations of the brain, skull and spinal cord
23
Q
Why are culicoides (midges) so challenging to control?
A
Culicoides (midges) have an extensive breeding habitat
24
Q
Which three methods can be used to control culicoides (midges)?
A
Midge eater machines
Insecticides/screens
House animals during the culicoides most active period
25
Identify this ectoparasite
Melophagus ovinus (sheep ked)
| Hairy, wingless, tarsal claws, robust legs
26
How are Melophagus ovinus (sheep ked) spread?
Melophagus ovinus are spread via direct contact
27
Melophagus ovinus (sheep ked) females are viviparous. What does this mean?
Melophagus ovinus (sheep ked) females give birth to live larvae
28
How often do Melophagus ovinus (sheep ked) females give birth to live larvae
Every 10-12 days
29
How do Melophagus ovinus (sheep ked) decrease the value of sheep wool?
When Melophagus ovinus (sheep ked) feed on blood meals, their bite causes intense pruritus (itching) causing the host to rub, scratch and bite which damages the wool
30
What can occur due to heavy Melophagus ovinus (sheep ked) infections?
Loss of body condition
Anaemia
31
Which two methods can be used to control Melophagus ovinus (sheep ked)?
Shearing
Insecticides
32
What is myiasis?
Myiasis is the invasion of a living vertebrate animal by fly larvae
33
What is obligate myiasis?
Obligate myiasis is when the myiasis is an essential part of their lifecycle
34
What is facultative myiasis?
Facultative myiasis is the exploitation of living tissue by larvae but it is not an essential part of their lifecycle
35
What are the six possible consequences of myiasis?
Severe tissue damage
Ulceration
Loss of tissue function
Putrid discharge
Secondary infection
Death
36
Give an example of a fly that causes obligate myiasis
Hypoderma (warble flies)
37
What are the two main species of Hypoderma (warble flies) that affect cattle?
Hypoderma bovis
Hypoderma lineatum
38
(T/F) Hypoderma (warble flies) have been eliminated in the UK
TRUE. However imported cattle still have a risk of carrying Hypoderma (warble flies)
39
Describe the lifecycle of Hypoderma (warble flies)
1. Females lay eggs on the hair of the host
2. Eggs hatch and L1 larvae penetrate the host skin via hair follicles
3. L1 migrate to the spinal canal or oesophageal wall via connective tissue or nerve pathways
4. L1 larvae then migrate to the sub-dermal tissue of the back of the host to complete development
5. As the larvae develop, they pierce the skin of the host to allow for respiration
6. L3 larvae erupt via the skin opening and land on the ground where they will pupate
7. Adult Hypoderma emerge from the pupae -->
| H. bovis migrate to spinal cord and H. linetum migrate to oesophagus
40
What is 'butchers jelly'?
As the Hypoderma L1 larvae migrate through the tissue, they secrete digestive enzymes and macerate the tissue with oral hooks, creating gelatinous tracks known as 'butchers jelly'
41
What are 'warbles'?
'Warbles' are lumps on the skin caused by the L2 and L3 Hypoderma larvae
42
How do Hypoderma (warble flies) cause economic loss?
Fly worry
'Butchers jelly' decreases meat value
Hide perforation decreases leather value
43
(T/F) Hypoderma (warble fly) infestation is a notifiable disease
TRUE.
44
Give an example of flies that cause facultative myiasis
Blow flies
45
What are the three species of blow fly that are of veterinary importance in the UK?
Lucilia (green bottle)
Calliphora (blue bottle)
Phormia (black bottle)
46
What are primary blow flies?
Primary blow flies can initiate myiasis on living animals without the need for existing tissue damage
47
What are secondary blow flies?
Secondary blow flues cannot initiate myiasis and instead need existing tissue damage or existing fly strike
48
Which species' of blow fly are primary flies?
Lucilia (green bottle)
Phormia (black bottle)
49
Which species of blow fly is a secondary fly?
Calliphora (blue bottle)
50
What kind of tissue are blow flies attracted to to initiate myiasis?
Moist tissue
Faecal contaminated tissue
Necrotic tissue
51
Which three species are most commonly associated with myiasis?
Sheep
Poultry
Rabbits
52
What are the four types of myiasis?
Body strike
Breech strike
Poll strike
Penile strike
53
How does rainfall increase the risk of myiasis in sheep?
Rain wets the wool and can cause wool rot. The odour of wool rot attracts the female blow flies to lay their eggs in the wool
54
Which breed characteristics can make sheep more susceptible to fly strike?
Thin wool (body strike)
Wrinkled/folded skin (body strike)
Horned (poll strike)
55
How do diarrhoeal infections increase the risk of myiasis?
Diarrhoeal infections lead to faecal contamination around the breech and tail which attracts the female blow flies to lay eggs and cause breech strike
56
Which five methods can be used to control blow fly myiasis in sheep?
Prevention of diarrhoea
Clip wool around the breech
Tail docking
Shearing
Remove any carcasses from the environment
57
What can happen to farmers which do not prevent or treat myiasis within their flock?
Prosecution for animal cruelty
58
Which species of blow fly most commonly causes myiasis in pet rabbits?
Lucilia (green bottle)
59
Which type of myiasis is most common in pet rabbits?
Breech strike
60
Which class of ectoparasites incorporates mites and ticks?
Arachnida
61
What are the three forms of allergic dermatitis caused by ectoparasites?
Flea allergic dermatitis (FAD)
Pediculosis (lice)
Mange
62
Give an example of a non-burrowing species of mite
Psoroptes ovis
63
Which mange disease is caused by Psoroptes ovis?
Sheep scab
64
(T/F) Sheep scab is a notifiable disease in the UK
TRUE.
65
Describe the pathogenesis of sheep scab
Antigens in the faeces of Psoroptes ovis mites causes a type I hypersensitivity reaction, stimulating skin inflammation and serous exudate secretion. This serous exudate dries to form a scab with a moist border and inflamed skin. Psoroptes mites are active at the border of the scab and as the mite population increases, the scab will extend. These scabs cause pruritus causing the host to rub and bite leading to hair loss and skin excoriation
66
What are the five clinical signs of sheep scab?
Wet, discoloured wool
Restlessness
Wool loss
Bleeding open wounds
Loss of body condition
67
How should sheep scab be diagnosed?
Part the wool of the sheep and look for scab lesions. Take a skin scraping at the edge of the lesion in order to confirm that the species of mite present is Psoroptes ovis under the microscope
68
Identify this ectoparasite
Psoroptes ovis
| Eight legs, rounded body, pointed head
69
Identify this ectoparasite
Bovicola ovis (often mistaken for sheep scab as has a similar clinical presentation)
| Six legs, elongated body, rounded head
70
Give an example of a burrowing species of mite
Demodex canis
71
Where specifically in the skin are Demodex mites found?
Demodex mites are commensal mites found in the hair follicles and sebaceous glands of the skin
72
Why might you need to take a deep dermal skin sample to identify Demodex mites under the microscope?
As the population of demodex mites expands, they begin to extend into the dermal layer of the skin
73
How is Demodex canis transmitted in puppies?
Demodex canis is transmitted by prolonged direct contact when puppies are suckling
74
How does a Demodex canis infestation affect healthy dogs?
Demodex canis is a commensal mite that lives in the skin so most dogs will have mild, localised mange that resolves on its own
75
How does a Demodex canis infestation affect immunosuppressed dogs?
Demodex canis can cause Generalised Demodecosis in immunosuppressed dogs
76
What are the two forms of Generalised Demodecosis?
Squamous generalised demodecosis
Pustular generalised demodecosis
77
What are the three clinical signs of squamous generalised demodecosis?
Alopecia
Desquamation
Thickened skin
78
What are the four clinical signs of pustular generalised demodecosis?
Pustules oozing blood, pus and serum
Erythema
Hyperpigmentation
Severe disfigurement
| Erythema (skin redness)
79
What can occur if bacteria infects pustular generalised demodecosis lesions?
Septicaemia
80
What should be used to treat pustular generalised demodecosis?
Long term Amitraz rinses
81
What is the main species of tick that is of veterinary importance in the UK?
Ixodes ricinus (European sheep tick)
| ri-ci-nus
82
Which species of animals are hosts to Ioxdes ricinus ticks?
All mammals and birds
83
What are three of the distinctive morphologies of the Ixodes ricinus tick?
Anterior anal groove
Inornate
Overlapping spur at their coxae (leg base)
84
Why are Ixodes ricnicus ticks so effective as vectors?
All stages of the Ixodes ricnicus tick are obligate blood feeders and each stage feeds on a different host
85
Describe the lifecycle of the Ixodes ricnicus tick
1. Male and female mate on the host and the female feeds on the host for 14 days
2. Female drops from the host and lays thousands of eggs
3. Larvae hatch from the eggs in autumn and enter quiescence over winter
4. In late spring/early summer, the larvae actively quest for a host and feed for 6 days
5. Larvae moult into nymphs in autumn and these nymphs enter quiescence over winter
6. In late spring/summer, the nymphs actively quest for a host and feed for 6 to 8 days
7. In autumn, nymphs moult into adults and the adults enter quiescence over winter -->
86
How are Ixodes ricnicus ticks adapted to recognise passing hosts?
Ioxdes ricnicus ticks have sensory organs known as haller's organs which detect temperature changes, light intensity and vibrations
87
Which disease can occur due to a heavy Ioxdes ricnicus infestation?
Anaemia
88
Which disease is caused by the secondary infection of tick bite lesions by staphylococcus?
Tick pyaemia
89
What are the four clinical signs of tick pyaemia?
Septicaemia
Meningitis
Arthritis
Abscesses
90
Give an example of a protozoa that uses Ixodes ricinus as a vector
Babesia divergins (B. divergins)
91
Which disease is caused by Babesia divergins (B. divergins)
Red water fever
92
What are the three clinical signs of red water fever in ruminants?
Pyrexia
Anaemia
Haemaglobinuria
93
Give an example of a virus that uses Ixodes ricnicus as a vector
Flavivirus
94
Which disease is caused by Flavivirus?
Louping ill
95
What are the three clinical signs of Louping ill in ruminants?
Encephalitis
Abnormal gait
Death
96
Give an example of a rickettsia that uses Ixodes ricnicus as a vector
Anaplasma
97
Which disease is caused by Anaplasma?
Tick-borne fever
98
What is the main clinical sign of Tick-borne fever in ruminants?
Abortion
99
Give an example of a bacteria that used Ixodes ricnicus as a vector
Borellia burgdorferi (B. burgdorferi)
100
Which disease is caused by Borellia burgdorferi (B. burgdorferi)?
Lyme disease
101
What are the four clinical signs of Lyme disease?
Persistent fever
Arthritis
Lameness
Nephritis
102
What is a 'dead end host'?
A 'dead end host' is an intermediate host that doesn't allow further transmission to the primary host
103
What is an arbovirus?
An arbovirus is a virus that is maintained in the environment through transmission between susceptible vertebrates and haematophagous arthropods
104
What are the two main functions of arthropods in the arbovirus lifecycle?
Arthropods act as a reservoir through promoting persistence and amplification of the virus and act as a vector through promoting transmission of the virus
105
How can arthropods act as mechanical vectors for virus transmission?
Arthropods act as mechanical vectors where the virus does not grow within the arthropod but is still transmitted by the arthropod
106
What are the three potential routes of arbovirus transmission between arthropods?
Transmitted between life cycle stages
Venereal transmission
Transmitted by close feeding on the same vertebrate host
| Venereal (through mating)
107
How are arboviruses transmitted between arthropods and vertebrate hosts?
Arboviruses are transmitted between arthropods and vertebrate hosts when the arthropod bites and feeds on the host
108
How is climate change affecting the distribution of arboviruses?
Climate change will impact global vector distribution leading to emerging arbovirus diseases in new geographical locations
109
List three diseases caused by arboviruses
Blue tongue virus
West Nile virus
African swine fever virus
110
Which family of viruses cause the Blue tongue virus?
Reovirus
111
Describe the structure of the Reovirus which causes the Blue tongue virus
Non-enveloped RNA virus with a segmented genome
112
Which arthropod vector transmits the Blue tongue virus?
Culicoides (midges)
113
During which months of the year is Blue tongue most prevalent?
Blue tongue virus is prevalent between March and September
114
What is the most pronounced clinical sign of Blue tongue virus?
Tongue cyanosis
115
What are the three main methods used to control the Blue tongue virus?
Serotype specific vaccinations
Vector control
Import control
116
Which family of viruses cause the West Nile virus?
Flavivirus
117
Describe the structure of the Flavirus which causes the West Nile virus
Enveloped RNA virus
118
Which arthropod vector transmits the West Nile virus?
Mosquitos
119
What is the primary host of the West Nile virus?
Wild birds
120
What are the two 'dead end hosts' of the West Nile virus?
Horses
Humans
121
What are the three main methods used to control the West Nile virus?
Education
Vector control
Vaccines (in horses)
122
Describe the structure of the virus which causes African swine fever
Enveloped DNA virus
123
Which arthropod vector transmits African swine fever?
Ticks
124
What are the two primary hosts for African swine fever?
Warthogs
Bushpigs
125
(T/F) The primary hosts of African swine fever suffer from severe clinical disease
FALSE. African swine fever cause inapparent disease in their primary hosts
126
What is one of the main secondary hosts of African swine fever that suffer from severe clinical disease?
Domestic pigs
127
What are the three main methods used to control African swine fever?
Prevent contact with carrier pigs
Vector control
Meat and live animal import control
128
Which arbovirus diseases are notifiable?
Blue tongue virus
African swine fever virus
