Arachnida- Mites Flashcards
(116 cards)
1
Q
What is the taxonomy of mites?
A
Phylum: Arthropoda
Class: Arachnida
Order: Acarina
Grouping: Mites
2
Q
Mites have successfully colonized which areas?
A
nearly every known terrestrial, marine, and freshwater habitat
3
Q
Describe the diverse ecological niches of mites.
A
free-living
predatory
plant feeding
obligate parasitic
4
Q
What __% of asthma sufferers are allergic to:
A
85% of asthma sufferers are allergic to free-living house dust mites
5
Q
Majority of mites are _____, a small number are ______.
A
free-living, parasites
6
Q
What are the general characteristics of ticks and mites?
A
- body divided into 2 parts: cephalothorax and abdomen
- adults have 4 pairs of legs
- no wings
Characteristics of arachnids
7
Q
What is the veterinary importance of ticks and mites?
A
- vectors and intermediate hosts of other parasites
- irritation and traumatic lesions
8
Q
Describe mite morphology.
A
- small
- no wings, antennae, or compound eyes
- body consists of 2 parts
9
Q
What are the two body divisions of mites?
A
- gnathosoma/capitulum (head: pedipalps, mouthparts, and basis capituli)
- idiosoma (the rest): legs and abdomen
10
Q
What covers the idiosoma of the mite for sensory function?
A
hair called setae
11
Q
Larvae, nymph, and adult mites have how many pairs of legs?
A
larvae: 3
nymphs and adults: 4
12
Q
The tarsus of mites sometimes ends in what?
A
pretarsus with a claw or sucker, called a pulvilli
13
Q
Describe the basic mite life cycle.
A
- incomplete metamorphosis
- egg -> larvae -> 1-3 nymph stages -> adult
14
Q
How long does the life cycle of a mite take?
A
8 days to 4 weeks
15
Q
Parasitic mites are mostly endo or ectoparasites?
A
mostly ectoparasites, a few endoparasitic species that can be found in the lungs, nasal passages, or other tissues of birds, mammals, and reptiles
16
Q
Mites complete their entire life cycle where?
A
on the host
17
Q
Mites are spread by what?
A
direct contact between hosts
18
Q
Mites are classified based on what 2 things?
A
- location on host
- burrowing vs non-burrowing
19
Q
What is the infestation of animals by mites known as?
A
mange
20
Q
What 4 things do mites feed on?
A
blood, lymph, skin debris, or sebaceous secretions
21
Q
Mites can cause direct epidermal damage resulting in what?
A
inflammation
22
Q
Mite antigens (especially fecal antigens) result in what in the host?
A
cutaneous hypersensitivity (type 1)
23
Q
Mites are mechanical/biological vectors in what host?
A
mostly rodents
24
Q
Mites act as intermediate hosts for what?
A
tapeworms of cattle, sheep, and horses
25
Describe the suborder Orbatida.
beetle-like free-living mites that live in soil and vegetation and are commonly ingested by sheep and other grazing animals
26
Orbatida mites are intermediate hosts for what cestodes?
tapeworms of the family Anoplocephalidae
- Moniezia spp in cattle and sheep
- Anoplocephala spp in horses
27
What are the characteristics of non-burrowing mites?
- oval body and long legs
- live on skin surface
- feed on skin scales or some suck blood
- cause irritation resulting in dermatitis
28
What are the families of non-burrowing mites?
- psoroptidae
- cheyletidae
- dermanyssidae
- trombiculidae
29
What are the genera to know in the family psoroptidae?
- psoroptes
- chorioptes
- otodectes
30
What are the genera to know in the family cheyletidae?
psorergates and cheyletiella
31
What are the genera to know in the family dermanyssidae?
- dermanyssus
- ornithonyssus
- pneumonyssoides (pneumonyssus)
32
What are the genera to know in the family trombiculidae?
neotrombicula
33
What is the key characteristic of mites of the psoroptes genus?
long, 3-segmented pedicel
34
Psoroptes mites are permanent ____________.
ectoparasites
35
Where will you find psoroptes mites on the host?
on the skin of parts of the body well covered with hair
36
What is the lifespan of a psoroptes mite and how many eggs does the female lay?
lifespan is 4-6 weeks, females lay about 90 eggs
37
How long does the development of a psoroptes mite from egg to adult take?
10-14 days
38
What hosts do psoroptes mites infect?
sheep, cattle, horses and rabbits (host adapted strains)
39
What is the most important ectoparasitic disease of sheep?
psoroptic mange (sheep scab)
40
Besides sheep, what other species do psoroptic mange infect?
goats, cattle (cattle scab), horses, deer, rabbits, and elk/wapiti in the western U.S., where it is called the elk scab mite
41
How is psoroptic mange spread?
direct transfer between animals through markets, during transport, during winter feeding and fomites; spread rapidly over the body as the fleece thickens in colder months
42
When is psoroptic mange more prevalent?
in autumn, but outbreaks have been reported at all times of the year
43
Psoroptic mange population numbers decline after ____________.
shearing
44
Describe the veterinary significance of psoroptic mange.
- mites puncture the epidermis to suck lymph
- markedly pruritic
- local inflammatory swelling with serum leads to crust on the skin
- wool fall out/pulled out by sheep
45
A primary lesion from psoroptic mange occurs when?
as soon as 2 weeks after contact
46
What do psoroptic mites do since they do not thrive in the bare crusty patches?
migrate to the margins of the lesion and extend the process outwards
47
How is psoroptic mange diagnosed?
- history of movement
- clinical signs/lesions
- skin scraping of suspect lesions at the edge of the lesion
- serum ELISA (from 2 weeks post infection
48
A skin scraping helps in the diagnosis of psoroptes how?
- differentiates from Chorioptes
- rules out other parasites such as sheep keds and lice
49
How is psoroptic mange prevented?
- reliable source of replacement stock
- quarantine and treat new sheep
- avoid common grazing
- maintain a close flock
50
Psoroptic mange in rabbits is attributed to what species?
Psoroptes cuniculi; localizes in the ear
51
In the case of psoroptic mange in rabbits, what might happen to the ear canal?
auditory canal may be blocked with greyish debris
52
How is psoroptic mange treated in rabbits?
same as otodectic mange in cats and dogs
53
Chorioptes mites resemble Psoroptes except for:
- mouthparts are rounded: chewing type
- legs have large, cup-shaped suckers on short, unpointed pedicels
54
What species of chorioptes affects cattle, sheep, goats, horses, and rabbits?
Chorioptes bovis
55
What species of Chorioptes affects ear canals of reindeer in Canada?
Chorioptes texanus
56
What is the most common mange in cattle?
Choriptes bovis; less severe than psoroptic mange
57
What do chorioptes mites feed on?
debris on the skin surface, usually in the area of the legs or scrotum
58
What will cattle do as a result of Chorioptes mange on the legs?
stomp and scratch at legs
59
What happens as a result of Chorioptes mites on the scrotum in cattle?
scrotal dermatitis that leads to testicular atrophy and infertility
60
When is the Chorioptes mite population the highest?
winter
61
Where will chorioptic mange most commonly be seen in horses?
on the fetlock, usually the hind legs; more common in heavy-feathered horses
62
What are the two ear mites to know?
- otodectes cynotis: common ear mite of dogs, cats, and fox
- Raillietia spp: cattle and goat ear mite
63
How are Otodectes mites similar to Chorioptes mites?
Unsegmented pretarsus with cup-shaped pulvillus.
64
Where do Otodectes cynotis mites live?
Deep in the ear canal.
65
What is the veterinary significance of Otodectes cynotis?
- Ear inflammation causing crusts and exudate
- Head shaking and scratching that can result in otheamatoma
- Secondary bacterial infection such as purulent otitis externa
66
Where does Raillietia app affect dairy and beef cattle?
North America, South America, Europe, Western Asia, and Australia.
67
What does Raillietia spp result in?
- Usually relatively harmless: cause blockage of the auditory canal
- Severe cases: inflammation can cause hearing loss in some animals.
68
How are ear mites diagnosed?
Otoscopy and examining wax for mites.
69
What are the characteristics of mites of the family Cheyletidae?
- 'Walking dandruff' fur mites
- Surface mite of dog, cat, and rabbit
- Palps with claws.
70
What are the species to know within the Cheyletidae family?
- Cheyletiella yasguri (dogs)
- Cheyletiella blakei (cats)
- Cheyletiella parasitivorax (rabbits).
71
Describe the species affected by the Cheyletidae family.
Zoonotic; most common in dogs and cats, but can affect domestic animals and wildlife.
72
How do Cheyletidae mites manifest themselves?
- Dry and greasy scales on the head, shoulder, and back
- Minimal itching
- Skin scales shed onto hair/fur
- Mites move amongst debris, hence 'walking' dandruff.
73
What are the 3 species to know in the Dermanyssidae family?
- Pneumonyssoides caninum: canine nasal mite
- Dermanyssus gallinae: 'red mite' of poultry
- Ornithonyssus sylviarum: northern fowl mite.
74
Describe the appearance of Pneumonyssoides caninum.
- Nasal mite
- Oval, pale yellow color
- Occurs in nasal and paranasal sinuses of dogs.
75
What can Pneumonyssoides caninum cause in the host?
- Head shaking and reverse sneezing
- Excess nasal secretions and hyperemia of mucosa
- Impaired smell in working dogs.
76
What are other respiratory mites of importance besides Pneumonyssoides caninum?
Halarachne and Orthohalarachne of seals, sea lions, sea otters, and walruses.
77
Describe the characteristics of Dermanyssus gallinae.
- Red poultry mite
- Large with elongated, stylet-like chelicerae
- Greyish white color normally, but turn red when engorged.
78
What is the other poultry mite of importance and where is it found?
Ornithonyssus sylviarum (northern fowl mite); abundant in the USA.
79
What hosts do Dermanyssus gallinae infest?
Wild and domestic birds as well as other domestic animals associated with poultry houses.
80
What is the main ectoparasite of laying birds and poultry houses?
Dermanyssus gallinae.
81
What is the veterinary importance of Dermanyssus gallinae?
- Causes skin irritation and restlessness
- Causes anemia, lower egg production, and weight gain in a heavily infested bird
- Difficult to control and eradicate
- Zoonoses.
82
What are the characteristics of the Trombiculidae family?
- Mostly free-living
- Orange-red in color with tooth-like chelicerae and a palp with a claw
- Not host specific; dogs, cats, birds, rabbits
- Zoonotic.
83
When are the Trombiculidae family of mites most active?
Late summer and autumn.
84
Which stage or stages of the Trombiculidae family of mites is parasitic?
Only the larval stage.
85
What is the general appearance of burrowing mites?
Small, round mites with short legs.
86
What are the two families of importance within the burrowing mite group?
Sarcoptidae and Demodicidae.
87
What are the characteristics of Sarcoptes scabiei?
- Scab mite that causes scabies
- Numerous transverse ridges and triangular scales on dorsum
- Attacks all domestic mammals except cats and guinea pigs.
88
Sarcoptes scabiei pierce skin of host to feed on what?
Suck lymph and feed on young epidermal cells.
89
What is the veterinary importance of Sarcoptes scabiei mites?
- Sensitization to feces, skin molts, and saliva of the mite causes marked irritation in the host
- Exudate from skin inflammation forms crusts
- Skin of host becomes thickened and wrinkled due to excessive keratinization and proliferation of CT
- Widespread alopecia.
90
What animals are most commonly affected by sarcoptic mange and where?
Dogs: edges of ears, muzzle, face, and elbows; pigs: ears.
91
Sarcoptic mange causes serious disease in what animals?
Foxes, llamas/alpacas, and other wildlife.
92
Describe the zoonoses of sarcoptic mange.
- Humans are readily infected mostly from dogs
- Manifests as reddish, papular eruption with pruritus.
93
What are the clinical signs of sarcoptic mange?
- Erythema with papule formation initially followed by scale and crust formation/alopecia
- Intense pruritus leading to self-inflicted trauma
- If neglected the whole skin can become involved
- Dogs become progressively weak and emaciated and have a strong sour odor.
94
How is sarcoptic mange diagnosed?
Skin scraping.
95
Describe Notroedes cati.
- Cat scabies
- Resembles Sarcoptes but is smaller; has thumbprint-like striations and no spines on dorsum
- Very rare, highly contagious.
96
What areas of the cat does Notroedes cati affect?
Skin of face, neck, and ears.
97
What is the only burrowing mite of birds?
Knemidocoptes spp.
98
Describe the appearance of Knemidocoptes mites.
- Stalked pulvilli only in the male
- No spines or scales
- Resembles Sarcoptes.
99
What are the Knemidocoptes species of importance?
- K. mutans and K. gallinae of poultry
- K. pilae in parakeets
- K. jamaicensis in passerine birds, including canaries.
100
Where do Knemidocoptes mutans and K. gallinae affect poultry?
K. mutans: burrow under epidermal scales of legs and cause 'scaly leg'; K. gallinae: burrows in hair shaft and causes 'depluming itch.'
101
Where does Knemidocoptes pilae affect cage birds?
Burrows in non-feathered parts of the body causing 'tassel foot/scaly face.'
102
What are the characteristics of Demodicidae burrowing mites?
- Unlike Sarcoptidae in form and behavior
- Affects all mammals
- Demodecosis most common in dogs
- Can be found in normal skin flora
- All species are similar morphologically.
103
Where are Demodex spp found on the host?
Live in hair follicles and sebaceous glands; causing demodectic or follicular mange.
104
How are most of the Demodex species named?
- After their host, i.e. D. canis, D. bovis, D. ovis, etc.
- D. gatoi in cats
- D. folliculorum in man.
105
In what 3 ways is demodicosis in dogs classified?
- Age of onset
- Extent of lesions
- Secondary infection.
106
Describe the classification of canine demodicosis according to age of onset.
Juvenile (3-18 months):
- Seen either when the host is immunocompromised or has a mite-specific immuno-incompetency
- Spontaneous recovery
Adult (>4 years):
- Caused by immunosuppression or drugs/systemic disease.
107
What are the different classifications of canine demodicosis according to extent/location of lesions?
- Localized form
- Generalized form
- Squamous
- Pustular.
108
Describe localized form canine demodicosis.
- Good prognosis
- <4 lesions
- Lesion diameter 2.5 cm at most
- Lesions resolve within 6-8 weeks.
109
Describe generalized form canine demodicosis.
- Good prognosis depending on patient's health status
- >4 skin lesions
- >2.5 cm lesion diameter
- Feet sometimes also affected.
110
Describe squamous form canine demodicosis.
- Good prognosis
- Lesions vary from simple squamous epithelial shedding or depilation to small or large papules or nodules.
111
Describe pustular form canine demodicosis.
- Poor prognosis
- Secondary bacterial infection may occur leading to additional pustule formation.
112
True or false: pruritus always occurs with canine demodicosis.
False, no pruritus in uncomplicated cases, except for Demodex gatoi in cats.
113
What is the difference between Demodex cati and Demodex gatoi?
D. cati: not contagious and not pruritic; D. gatoi: contagious and pruritic.
114
Where does Demodex gatoi occur on the host?
Superficial keratin layers of the epidermis.
115
How is demodicosis diagnosed?
- Deep scrapings of the skin
- Even in normal animals you may see some mites, but a high proportion of larvae and nymphs indicated an expanding population
- Smear of sebaceous gland
- Skin biopsy to detect mites in hair follicles in severely infected dogs.
116
Describe Varroa destructor.
- External parasitic mite of honeybees
- Adult mites feed on body of both adults and bee larvae
- Vectors of several viruses such as deformed wing virus
- Originated in Asia, but are now worldwide.
