Parasitology - Arthropod 3 Flashcards
Body divisions of ticks and mites
Gnathosoma - mouth part
Idiosoma - remainder of body
Cause & symptoms of mange
Skin disease caused by mites
Alopecia, erythema, pruritus — pyoderma
Similarities of mites & lice
Host specific
All life stages on host/parasitic
Short life cycle (few weeks)
Transmission - direct contact
Differences of diagnosis of lice & mites
Mites - skin scraping
Lice - visual/microscope
Subsurface mites
Sarcoptes
Knemidocoptes
Demodex
Surface mites
Otodectes
Chorioptes
Psoroptes
Morphology of sarcoptic mites
Round bodies
Posterior legs visible ventrally
Burrowing mites in epidermis
Most common cause of mange
Sarcoptic mites
What species do sarcoptes scabiei infect?
Dogs, pigs, cattle*, horses**
Very host specific
Reportable in cattle
Pathogenicity of sarcoptes scabiei
Lesions on face, ears, legs
Pruritus, alopecia, inflammation
Chronic sarcoptic mange
Sarcoptes scabiei
Alopecia, thickened wrinkled skin
Pyoderma - secondary bacterial infection is common
Self inflicted trauma from scratching
Range of difficulty when diagnosing sarcoptes scabiei
Acute mange - easier, lesions more clear
Chronic mange - more difficult, no clear lesions, bacterial infection contamination
Treatment and control of sarcoptes scabiei
Drugs are effective, no known resistance
Zoonotic - humans can contract lesions but wont reach a full life cycle
Sarcoptic mites alternate hosts
Cats, rabbits, Guinea pigs
Demodex spp morphology
Cigar with legs, burrow deeper in skin
Larvae have 3 pairs of legs
Adults have 4 pairs of legs
What animal species have multiple mite Demodex species?
Cats and dogs
Location of Demodex mites
Hair follicles or sebaceous glands
Part of the normal skin flora (selective immunity)
Clinical signs of Demodex mites
Disease is common is dogs
Infection varies based on problem in immune system
Localized or generalized
Features of surface mites
Otodectes, chorioptes
Not borrower, superficial
More oval, longer legs, posterior legs are visible dorsally
Life cycle min 2 weeks
Location & pathogenesis of Otodectes cynotis
Ear canal of dogs, cats, ferrets
Most common in cats, easily transmitted
Cause otitis externa — pruritus
What mite causes coffee ground appearance?
Otodectes cynotis
Surface mite
Chorioptes spp
Most common large animal mite
Specifically in cattle
Pathogenesis & location of chorioptes
Cattle: tail head, back of udder/perineal region
Small ruminants: scrotum, can cause infertility
Horses: lower leg/body
Order Acarina - ticks
Importance
Bite wounds
Blood loss
Tick paralysis
Transmission of pathogens**
Tick-borne diseases
Lyme borreliosis
Anaplasmosis
Babesiosis
Ehrlichoiosis
RMSF
Cytauxzoonosis
Two families of ticks
Hard ticks - important
Soft ticks
Nomenclature for hard ticks
Ixodidae
Nomenclature for soft ticks
Argasidae
Appearance of ixodids
Shiny, scutum distinguishes M/F
Mouth parts project forward
Life stages & important of molting in ticks
Egg, larva, nymph, adults
Cuticle restricts growth - molt occurs in environment
All common ticks are 3-host ticks
Morphology of nymphs
M/F have 8 legs
Lack genital opening
Morphology of adult ticks
M/F have 8 legs
Genital opening
Mate on host
Females lay eggs in environment & die
Attachment tools for ticks
Hypostome - needle
Palp - gribbers
Tick feeding
Slow feeding, several days
Rapid feeding, 12-36 hours prior to detachment
Blocking functions of tick saliva
Histamine blocker
Anticoagulant
Paralytic toxins cause ascending motor paralysis
Enlarging features of tick salvia
Cytolysins enlarge feeding lesion
Vasoactive mediators that increase vascular permeability
Facilitated transmission (horizontal)
Trans-stadial transmission
Picks up disease as larva or nymph, transmits to subsequent host
Facilitated transmission (vertical)
Transovarial transmission
Disease agent in female tick passes into eggs and is passed through subsequent stages
How many common hard ticks species?
Big 4 species
Common name of dermacentor variabilis
American dog tick
Common name of Ixodes scapularis
black legged/deer tick
Common name for Amblyomma Americanum
Lone star tick
Common name for Rhipicephalus sanguineus
Brown dog tick
Common name of invasive tick in US
Asian longhorn tick
Scientific name for Asian longhorned tick
Haemaphysalis longicornis
Argasid ticks
Soft ticks
More successful in environment
Several nymph stages
Don’t transmit major diseases in the US
