6.3 Arthropods 3 Flashcards
1
Q
mites are in what class
A
Arachnida
2
Q
Mites; General types of mites
A
- itch and mange mites
- bloodsucking mites
- mites in the respiratory system
- mites in the subcutaneous tissues
3
Q
Mites; Morphology
A
- Smaller than ticks with membranous cuticle
- Capitulum or “false head”
- anterior and terminal
- mouthparts - hypostome is unarmed
- 4 pairs of legs as adults
- Larvae look like adults but have 3 pairs of legs
- Nymphs look like adults with 4 pairs of legs but are not sexually mature
4
Q
Mites; General Life Cycle
A
- all have simple metamorphosis
- life cycle completed on one host, host specific
- all follow the general plan of egg to larva to nymph to adult
- feed on hair, fur, skin, secretions, etc.
- diverse morphological variations depending on host and location on host
5
Q
Life Cycle - Mites
A
Egg > Larva (3 pairs) > Nymph (4 pairs) > Adults (4 pairs)
6
Q
Sarcoptes scabiei diseases
A
scabies/sarcoptic mange mite, itch mite
7
Q
Sarcoptes scabiei; general hosts, site of infection
A
- wide variety of hosts - specific strains for each
- Sarcoptes sp. burrow into stratum corneum
8
Q
Sarcoptes scabiei; Adult morphology
A
- oval, short-legged mite with posterior two pairs not extending beyond edge of body
- body has many spines, particularly on dorsum
- pedicels of pretarsi are long and unsegmented
9
Q
Sarcoptes scabiei; Life Cycle, transmission
A
- all stages on one host, short survival off host
- females tunnel into epidermis and lay eggs
- larvae, nymphs and newly emerged adults found in skin pockets
- transmission by direct contact
10
Q
Sarcoptes scabiei; Pathogenesis
A
- burrowing mites - secretions and excretions may lead to hypersensitivity
- self inflicted damage may cause alopecia and bleeding leading to scabbing
- secondary infections common and may progress to pyoderma
- emaciation and death may result
11
Q
Sarcoptes scabiei; Lesions/Clinical Signs, predilection sites
A
- initial papule ruptures and exudes serum, pruritus evident
- progresses to thickened, dry, flaky, skin (hyperkeratosis
and exfoliation) with scabbing and alopecia - chronic disease may continue for months with continuing pruritus - initial lesions usually in less haired areas
- predilection sites:
-dogs - head, ears, elbows, hocks, ventral body
-ruminants - head and neck
-pigs - head around ears, nose and eyes, inner thighs
12
Q
Sarcoptes scabiei; Diagnosis
A
- skin scrapings with a glycerine covered scapel performed at the edge of a lesion - examine microscopically
- detritus from a scraping may be digested using 5% potassium hydroxide (near boil)
- mites may be mounted in Berlese solution
13
Q
Sarcoptes scabiei; Treatment
A
- hair should be clipped and all crusty material removed from affected areas prior to treatment
- selamectin has label claim for dogs - up to 2 doses required
- moxidectin in Advantage-Multi highly effective
- large animals – various endectocides have activity
and label claim against sarcoptic mange mites - older treatment - amitraz provides good control after a single dermal application – note toxicity to humans
14
Q
Demodex spp.
A
(follicle mite or demodectic mange mite)
15
Q
Demodex spp.; general; where do they infect, what do they cause, hosts
A
- infect hair follicles, sebaceous and apocrine glands
- cause demodectic mange or demodicosis
- many species infected with their own particular species of follicle mite