Flashcards
Arthropods
Cards in this deck (37)
- 1Common characteristics of arthropod parasitesGenerally ectoparasites
They have a tough, waterproof exoskeleton
They have legs and claws to grip to skin and hair or to burrow into skin
Often have biting or piercing mouth parts
They are parasitic for a variable portion of their lifecycle - 2Insecta6 legs
1-2 pairs of wings
separate head, thorax and abdomen
One pair of antennae - 3AcarinaEight legs
wingless
no antennae
No body segmentation - 4Arthropod reproductionSeparate sexes
Eggs hatch to a mini adult (nymph) or a larvae
Development via rearrangement of tissue or metamorphosis - 5Stages of developmentLarva with instars
Nymph - small adult structure
Adult - sexually mature - 6Complete metamorphosisLarva stage with skin that hardens or darkens forming a puparium, this protects the tissue underneath
Metamorphosis inside puparium (pupa) that undergoes complete reorganisation of tissue. Can be inside a silk cocoon that is spun by the final larvae - 7Gradual metamorphosisJuvenile stages are nymphs with a similar body plan to adults
They undergo various moults to transition from a juvenile to the adult - 8BlowfliesDiptera
Soilage by urine or faeces and bacterial or fungal disease attracts flies and provides a good habitat for larvae to develop
Most are facultative parasites, they don't require a living animal. Dense fleece provides a good habitat for larvae to develop as they undergo several larval stages (1-3). L2 stage burrows into skin - 9Primary blowfliesInitiate fly strike in intact skin
- 10Secondary blowfliesRequire the presence of a pre-existing wound to create fly strike
- 11Primary fly speciesLucilia sericata - green
Lucilia cuprina - green, obligate fly
Calliphora stygia - black/grey - 12Secondary fly speciesChrysomya rufifacies - green with black bands
Calliphora sp. - blueish - 13FlystrikeCan affect all sheep, but most common in young with dags. Crutch, pizzle back, feet (rot)
Primary flies: L2 use enzymes and hooked mouth parts to breakdown skin and can damage SQ tissue
Secondary flies: greatly enlarge the damaged area
Fleece becomes discoloured, animals get septicaemia and dehydration and die - 14Typical blowfly lifecycleEgg laid by female
Larva (maggot) hatches and uses mouth and enzymes to feed on substrate it was laid on
It grows and moulds to the third stage where it falls off and buries itself in the ground
It emerges as an adult then reproduces and lays eggs - 15Gasterophilus spp.Larvae are internal parasites
Gasterophilus sp.
Parasitises the mouth and stomach of horses
Eggs are laid on the coat
They hatch once consumed when licked off
Larvae migrate in oral tissue and attach to the stomach wall for 8-9 months. In the dorsal, non secretory portion of the stomach and the duodenum. These areas also have air pockets.
They pass out in the faeces and pupate in soil
Life cycle is ~1year - 16FleasOnly adults are parasitic. Laterally flat
Have piercing mouth parts to suck blood
Eggs are laid on the animal and fall to the ground to contaminate the environment and bedding
Maggot like larvae live in the environment off flea poo that is rich in blood
Pupate in a cocoon made from grit and dust where they pupate to the adult. If no suitable hosts, flea stays in cocoon
Prefer nest animals to keep larvae close
Can cause anaemia and irritation plus transmit disease (Didpylidium caninum) - 17Flea speciesCtenocephalides felis: cats, dogs and humans. Most common
Ctenocephalides canis: cats, dogs and humans
Pulex irritans: Pigs and humans - 18LiceFlat DV, wingless
Biting or sucking
SPend entire lifecycle on host, very specific
Eggs attach to hair shafts
Nymph hatches from egg and grows via a series of moults
numbers peak in winter due to thicker coats and on sicker animals
Anaemia, hypersensitivity and H for Dipylidium caninum - 19HPediculus humanus corporis
Pediculus humanus capitis
Phthirus pubis - 20TicksArachnids with 8 legs
All are parasitic and live on and off the host
Blood feeders
1-2cm when engorged
Blood converted to 1-2000 eggs
Once engorged, female drops off and lays her eggs in the environment. - 21MitesArachnids with 8 legs
Some are free living
Spend whole lifecycle on host
Have biting mouth parts - 22Tick palpsmouth parts:
Dorsal palps have cutting blades to slice skin
Ventral palp with spines allows for grip so it doesn't fall off once engorged and secretes protein to keep it in place. Enzymes are released to digest some tissue allowing blood to pool and some anticoagulants. - 23Tick lifecycleSix legged larva hatches from egg
Larva finds host to feed on
Some ticks will stay on one host, others will drop and find another
Larvae moults to 8 leg nymph
Nymph feeds and moults to adult
Egg laying is always in the environment - 24Haemaphysalis longicornisDomestic animal tick in NZ, introduced from Australia. No male adults
Reproduce via parthenogenesis
3 host tick
Winter: unfed nymphs stay in sheltered areas on pasture
Spring: Nymphs find a host, feed, drop and moult
Early summer: Adults are seen and eggs laid
Late summer: Larvae - 25How is haemaphysalis longicornis harmful?Remove blood from the animals. Emergence of adults coincides with that of young animals
Vectors for protozoan diseases
In NZ: vector for protozoan parasite Theileria orientalis causing anaemia in cattle - 26common tick areassheep axilla
cattle and udder
deer ears and antler bud - 27Bovine TheileriosisIKEDA strain of B. orientalis introduced sometime around 2012
Prior to 2012, only a small number of cases and only the CHITOSE strain.
Recent cases causes anaemia, stillbirth, abortion, reduced milk production, and 1.6% mortality - 28MitesVet small ~1mm
Ectoparasites: some burrow into skin, there are ear and follicular mites
Very host specific
spread via direct contact - 29Mite lifecycleEgg released by female
6 legged larva
1-3 nymph stages
Adult - 30Non-burrowing mitesChorioptes bovis: leg and scrotal mange in horses, cattle and sheep
Psoroptes ovis: sheep scab mite. Not in NZ
Psoroptes cuniculi: ear mite of horses, rabbits and cattle - 31Otodectes cynotisNon burrowing mite in the ears, face and tail of cats and dogs
Causes irritation in ears and can be seen in the wax
Contagious
Promotes bacterial overgrowth and yeast infections - 32CheyletiellaFur mites
On the body of cats, dogs and rabbits
Have large palpal hooks - 33Burrowing mitesSarcoptes scabei
Numerous hosts
Causes mange
adults tunnel in the skin causing severe itch
Common on dogs, hedgehogs and pigs
have short legs
Pinna and ventral skin often most affected. Lichenification of skin that is crusty and dry and becomes cracked - 34Folicular mitesDemodex
Each species adapted to a particular host
Mange uncommon on dogs
Their entire lifecycle is within the follicle
Mostly considered commensal
Cause pustules in pigs and cattle - 35Demodectic mangePresence of demodectic mange in dogs indicates some kind of immune disorder
young staffies and dobermans and old dogs most common
Can be localised or generalised. Follicles rupture into the dermis causing inflammation and red, nodular skin. Not as itchy as other kinds of mange
Long term steroid treatment can cause mange - 36Diagnosing mangeSicky tape: cheyletiella
Scrapes: Sarcoptes and Demodex
Brushing: burrowing and non-burrowing mites (Sarcoptes)
Pustules: demodex
Faecal examination - demodex ingested via grooming - 37BrushingStand patient in clean surface and give a vigorous brush against the normal direction to dislodge mites
Collect material and digest it with KOH to remove skin and hairs. Only mites will remain
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- Infectious disease Flashcards on Arthropods , created by Kelly Scott on 13/07/2020.
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- Kelly Scott
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