Parasitology Flashcards
1
Q
why do parasites live on the skin
A
food
habitat
ease of access
2
Q
what are the cons of parasites living on the skin
A
- requires access to specific host and location on host
- must be able to avoid defenses and navigate skin/hair/etc
3
Q
insects
A
fleas, flies, lice
4
Q
insect characteristics
A
- 3 body segments (head, thorax, abdomen)
- 0, 1, 2 pairs of wings
- 6 legs
- antennae, eyes
5
Q
arachnids
A
ticks, mites
6
Q
arachnid characteristics
A
- 2 body segments (fused head and thorax, abdomen)
- no wings
- 8 legs
7
Q
incomplete development life cycle
A
immature stages resemble the mature stages
- lice
- ticks, mites
8
Q
lice life cycle
A
egg –> nymph –> adult
9
Q
tick and mite life cycle
A
egg –> larva –> nymph –> adult
10
Q
complete development life cycle
A
different stages look distinctly differently
- fleas and flies
11
Q
flea and fly life cycle
A
egg –> larva –> pupa –> adult
12
Q
lice characteristics
A
- obligate ectoparasites
- macroscopic
- HIGHLY host specific
- cause pruritus
- pathogen vector
13
Q
mites
A
- sarcoptes
- demodex
- otodectes
- cheyletiella
- notoedres
- chorioptes
- psoroptes
14
Q
sarcoptes scabiei
A
- burrowing mite
- superficial
- 4 visible legs, 4 on ventral aspect
- highly contagious
- can be zoonotic
- cause pruritus
15
Q
sarcoptes scabei host
A
dogs
pigs
16
Q
how to diagnose sarcoptes scabei
A
superficial skin scraping
17
Q
demodex
A
- obligate ectoparasite
- live in hair follicles
- host specific
- localized vs generalized
18
Q
how to diagnose demodex
A
deep skin scraping
19
Q
demodex hosts
A
dogs, mammals
20
Q
localized demodicosis
A
circumscribed alopecia, erythema, scaling
- young animals (perinatal)
- spontaneous remission
- NON pruritic
- no treatment
21
Q
generalized demodicosis
A
diffuse of patchy generalized alopecia with scaling, crusting, chronic skin changes
- older animals
- genetic component
- secondary pyoderma
- HIGHLY pruritic
- requires treatment
22
Q
otodectes
A
ear mites - live on the surface of external ear
- cause otitis externa
- highly pruritic
23
Q
how to diagnose otodectes
A
otoscopic exam, ear swab
24
Q
otodectes host
A
cats, dogs
25
cheyletiella
fur mites - walking drandruff
- diagnose with acetate tape, swab, or comb
26
notoedres
- highly pruritic
- cause chronic infections --> severe lichenification
- affects ears and face
- 4 visible legs, 4 on ventral aspect
27
how to diagnose notoedres
skin scraping
28
notoedres host
cats
29
chorioptes
- non-burrowing mite
- causes mange - excessive crusts, scales, and skin thickening, pruritus
30
chorioptes host
livestock - sheep especially
31
psoroptes
- non-burrowing mite
- affects livestock and rabbits
- affects ears of rabbits
32
most common flea genus
ctenocephalides felis - for both dogs and cats
33
flea characteristics
- bloodsucking ectoparasites
- jump, do not fly
- host preferred but not specific
- cause flea allergy dermatitis
34
what stage of fleas are parasitic
adults only
egg, larvae, and pupa live off host
35
unique characteristics of flea pupae
can survive up to 140 days in cocoon
require host presence to pupate
36
flea allergy dermatitis
severe pruritus and dermatitis associated with flea infestation
37
3 major hard tick types
- ixodes
- dermacentor
- rhipicephalus
38
tick characteristics
- bloodsucking ectoparasites
- cause primary and secondary injury to host
- incomplete development
- females are larger than males with small scutum
39
festoons
small groove adornments along the back margin of the abdomen
- ixodes do NOT have festoons
40
secondary injury of ticks to hosts
- exsanguination
- secondary parasitic infection
- dermatoses
- paralysis toxicosis
- pathogen vector
41
hard and soft ticks
hard: visible head and mouthparts from dorsal view
- use 3 different hosts in life cycle
- feed for days
soft: no visible head and mouth parts from dorsal view
- use 1 host in life cycle
- feed for minutes
42
dermacentor
common tick in davis
- ornamental
43
ixodes
Lyme disease vector
- no festoons
44
rhipicephalus
brown dog tick
- indoor/outdoor ticks
45
sheep keds
flies that look like ticks
- have piercing mouthparts and feed on blood as adults
46
ked life cycle
1. females lay egg
2. larvae develops inside the female (feed from milk gland)
3. female births a live prepupa
4. prenups immediately pupates after birth
47
bot flies
cuterebra
- no obligate host; infects hosts that ingest their eggs
- larvae encyst beneath the skin and pupa drops out into environment to pupate
- adults are NON feeding
48
blow flies
calliphora
- colorful adults
- larvae eat decaying or living flesh
- adults are NON feeding
- cause myiasis
49
myiasis
fly larvae that infect living hosts, usually on necrotic skin or soiled tissue
- lay eggs on wounds/fleece
- larvae feed on necrotic skin
50
effects of myiasis
irritation
secondary bacterial infection
septicemia
toxemia
51
screwworm myiasis
caused by cochliomyia hominiovorax
- infects fresh wounds or bites
- reportable parasite to USDA
52
biting flies
cause annoyance, hypersensitivity, blood loss, and disease transmission
53
culicoides hypersensitivity
allergic response to fly bites in HORSES
- immediate and delayed reaction
- highly pruritic
54
cutaneous habronemiasis
nematode transmitted by flies into open wounds or margins of the eye
- migrates through skin causing excessive granulation + pruritus
"summer sores"
