arthropods

ectoparasites (arthropods)

• spiders, mites, ticks, crabs, crayfish, lobsters, fleas, millipedes, centipedes

• insects: cockroaches, beetles, bedbugs, bees, ants, wasps, mosquitoes, dragonflies, mothers, grasshoppers

arthropods

• jointed appendages covered with chitin

• hemocoel: body cavity filled with hemolymph

• GI: ventral mouth —> terminal anus

• dioecious; tremendous reproductive potential

mechanical vector

transmit but no development occurs

biological vector

serves as intermediate host

lice

• insects

• head, throax, abdomen

• species specific

mallophagan (biting lice)

bite at skin, hair, and feathers of the host; feed on dander and skin flakes

anopluran (sucking lice)

feed on the blood of host

fleas

• insects

• head, thorax, abdomen

• metamorphosis: egg —> larvae —> pupa —> adult

• order siphonaptera

mites and ticks

• NOT insects

• capitulum: mouth parts (head and thorax)

• idiosoma: abdomen

• NO metamorphosis: egg —> larvae —> nymph —> adult

• larval stage has 6 legs

Blister Beetles (coleoptera)

• common name: Blister Beetles/ Spanish Fly

• in US and Canada

• produce cantharidin: toxic substance in tissue that can burn tissue

• toxin produces blisters of skin, oral mucosa, epithelium of GI tract

• infest the ground below alfalfa hay; animals ingest through hay

• horses develop fatal colic

pediculosis

infestation with lice

mallophagan lice species

• dogs: Trichodectes canis

• cats: Felicola subrostratus

• cattle: Damalinia Bovis

• fowl: Goniocotes fallinae and Menacanthus stramineuste

• sheep: Damalinia ovis

mallophagan lice characteristics

• antennae = sensory appendages

• head = wider than widest part of thorax

• 3 pairs of legs; front legs tucked under head

• tarsal claw at end of leg

• abdomen: spiracles and chitinous pigmented bars on each segment

anopleuran lice species

• dogs: Linognathus sp.

• sheep: Solenopotes capillatus

• swine: Haematopinus suis

• monkeys: Pedicinus obtusus

anopluran lice characteristics

• antennae = sensory appendages

• head = narrower than widest part of thorax

• 3 pairs legs

• claws with a simple hook

• compound claw: claw at end of leg; complex claw with an end hook and “grasping thumb”

• abdomen: rows of hair on each segment

Solonoptes capillatus

• common name: little blue cattle louse

• anoplura

• location: face, neck, shoulders, back, tail of host

• transmission: from direct contact

• signs: dermatitis, anemia, production loss

Hematopinus spp

• common name: pig louse

• anoplura

• location: head, neck, or back of host

• signs: pruritus, alopecia, production loss; heavy infestation = anemia and death

nit

egg stage of lice

flies

• order diptera

• periodic parasites

• only adult females feed on blood

myiasis

flies larval form develops in tissue or organs of vertebrate hosts

biting flies

black flies, mosquitoes, horse flies, deer flies, tsetse flies, stable flies, horn flies, sheep ked

Simulium spp

• common name: black flies/biting midges

• larvae/pupae are aquatic

• attach to substrate

• painful bite

• spread Onchocerca cervicalis; roundworm bumps in skin and eyes

Culicoides spp

• common name: No-see-ums / sand flies

• horses are allergic to bites —> pruritis

• rubbing and scratching —> alopecia, excoriations, skin thickening

• Queensland itch, sweat itch, sweet itch

mosquitoes

• breed in standing waters

• females suck blood

• transmit protozoans, helminth, and viruses

• allergic dermatitis, fly attacks, toxemia, death

Horse flies (Tabanus) and deer flies

• large biting flies

• painful bites

• small, stout antennae

• mouthparts hang downwards from head

Glossina spp

• common name: tsetse flies

• sub sahara africa

• IH for african trypanosomiasis; sleeping sickness; Trypanosoma brucei

• male and female blood feed

Stomoxys calcitrans

• common name: stable flies; biting house flies

• male and female suck blood

• does not transmit diseases to humans

• vector for anthrax and equine infectious anemia

• IH for Habronema in horses

Haematobia irritans

• common name: horny fly

• bayonet like proboscis protruding from head

• host: cattle and buffalo

• cluster around base of horns = cold weather

• cluster on ventral midline = hot weather

• IH for filarial parasites

• lead to great loss of production in US

Melophagus ovinus

• common name: sheep ked / louse fly

• obligate parasite

• signs: significant skin damage, dermatitis, extreme pruritis

• do not lay eggs

• hairy, leathery, wingless

Musca autumnalis

• common name: face fly

• location: around eyes, muzzle, withers, neck, brisket, sides

• feed on saliva, tears, mucus

• can transmit keratoconjunctivitis / pink eye from Moraxella bovis (phoresis)

fly strike / strike

fly larva and adults parasitizing animals; infestation

fly larva

• bots, maggots, grubs, warbles

• ingest dead cells, exudate, secretions, and debris; not live tissue

• obligate and opportunistic

Cochiomyia hominivorax

• common name: screwworm flies

• attach to fresh wounds and lay up to 500 eggs

• larva enter wound and feed for 4 to 7 days

• important for South and southwestern US livestock

• feed exclusively on live flesh; high mortality

• reportable

Cuterebra spp

• common name: skin borer, warbles, wolve / rodent bot fly

• host: rabbits, squirrels, mice, rats, chipmunks, sometimes cats/dogs

• 2nd stage larval look like grub

• 3rd stage larval = coal black, heavily spined

• burrow near neck area, create hole, breathe from the hole

• surgical removal to prevent crushing and anaphylaxis

Hypoderma spp

• common name: cattle grub / ox warble / gadflies

• host: cattle, horses, sheep, humans

• signs: visible boil like cyst on back of host

• myiasis

Gastrophilus spp

• common name: stomach bot / bot flies / horse bots

• host: horse and donkeys

• location: in stomach

• can cause gastric ulcerations and colic

• fly eggs on legs/face that enter through mouth to stomach

• bot knife to remove eggs; treat with ivermectin

Oestrus ovis

• common name: nasal bot

• hosts: sheep and goats

• bee like

• cause purulent rhinitis or sinusitis

types of fleas

• cat and dog: Ctenocephalides felis (most common)

• dog: Ctenocephalides canis

• rabbits: Cediopsylla simplex; Odontopsylla multispinosus

flea characteristics

• piercing/sucking mouth parts

• metamorphism: egg, larval, pupal, adult stages

• larvae eat organic debris and form a cocoon

• eggs look like tiny pearls

• females = large orange/brown

• males = small and dark

fleas in rabbits and birds

• Cediopsylla simplex = eastern rabbit flea around face and neck

• Odontopsylla multispinosus = giant eastern rabbits flea on base of tail

• Echidnophaga gallinacea = stick tight flea of poultry; females put mouth in skin and stays like a tick

bartonellosis

• cats get infected from flea and tick bites

• signs: chronic inflammatory conditions affecting eyes, mouth, respiratory tract, GI system, and heart

Pulex irritans

• common name: human flea

• hosts: humans, pigs, dogs, cats

• pruritus and dermatitis

• vector for Yersenia pestis (bubonic plague)

arachnid characterisitcs

• 8 legs

• wingless

• can produce toxins

skin scraping

• #10 scalpel blade, dull and rounded

• superficial and deep scrape

• squeeze skin that needs to be scraped

• mineral oil to coat area scraped and blade

• scrape until capillary bleeding

mite characteristics

• acarina

• mouth parts and abdomen

• acariasis = infestation

• stages = egg —> larva —> nymph —> adult

• sarcoptiform or non sarcoptiform

sarcoptiform mites

• sarcoptidae: burrow / tunnel within epidermis (scabies)

• psoroptidae: on skin or ear canal (ear mite)

burrowing mites

• sarcoptidae

• round/oval shape

• legs have pedicels/stalks at tips

• jointed or straight

Sarcoptes scabei

• felis, suis, bovis, canis, equi, ovis

• signs: scaling, crusting, rashes; ears, lateral elbows, ventral abdomen

• pedal (pinnal response): rub tip of pinnae to see ipsilateral hindleg scratching response

• ZOONOTIC (canis)

• treatment: selamectin, moxidectin/imidacloprid

Notoedres cati

• host: cats and rabbits

• lesions at nose, lips, ears, rectum

• deep skin scraping needed and superficial skin scraping

• treatment: ivermectin

• prevention: selamectin, fipronil

Cnemidokoptes spp

• common name: scaly leg / scaly face mite

• host: birds

• location: non feathered part of bird

• signs: exudate, crusts, trauma, disfigurement

psoroptidae

• surface mites

• surface of skin / external ear canal

• spread through direct contact

• cause: otitis, inflammation, circling, head tilt, balance problems

Psoroptes cuniculi

• common name: rabbit ear mite / ear canker mite

• not zoonotic

• looks like ear canal packed with corn flakes

• signs: shaking head, scratching head/ears, loss of equilibrium

• spread with direct contact

• superficial skin scraping / sample ear crust

• treatment: milbemycin, advantage multi, thiabendazole/dexamethasone/neomycin solution

Psoroptes ovis

• host: sheep

• puncture epidermis; feed on lymphatic fluid

• crust forms —> wool/hair loss

• reportable

Psoroptes bovis

• host: cattle

• signs: lesions on withers, neck, rump

• reportable

Psoroptes equi

• host: horses

• location: mane and tail

• rare

• reportable

Chorioptes

• bovis: “foot and tail mite”

• equi: horses

• caprae: goats

• ovis: sheep

Otodectes cynotis

• canine, feline, ferret ear mite

• location: any area of body

• signs: pedal-pinna response (will shake leg); dark brown/black wax in ears (coffee grounds)

• causes otitis externa

• detection: otoscopic exam and ear swab

• treatment: clean ears; ivermectin, milbemycin, revolution, advantage multi, thiabendazole/dex/neomycin

Demodex canis

• nonsarcoptiform

• “fat worm” “tallow receiver”

• host specific

• follicular manage / “red mange”

• location: hair follicles and sebaceous glands

• infestation = demodicosis / demodectic mange

• common in immunocompromised (puppies/geriatric)

localized demodex

• patchy alopecia

• on muzzle/forelimbs

• can occur when dam nurses puppy

• can cause secondary bacterial infections

generalized demodex

• immune system defect

• dermatitis/alopecia across the whole body

demodex detection/treatment

• skin scraping (deep and superficial)

• medicated dip: amitraz

• goodwinol ointment (benzocaine, rotenone, lanolin)

• ivermectin

• repeated skin scrapes

Trombiculid

• common name: chigger, harvest mite, scrub itch mite

• affects animal and humans

• Eutrombicula spendens = common in North America

• signs: pruritus, irritation

• humans affected in face or where clothes are constrictive

• detection: orange/red mite seen in physical exam

Pneumonyssus caninum

• common name: nasal mite of dogs; “lung piercer”

• spread with direct contact

• signs: reddened nasal mucosa, sneezing, shaking head, rubbing nose, labored breathing, asthma, fainting

• detection: visible to naked eye; mites exiting nostrils

• treatment: ivermectin nasal flush

Cheyletiella parasitovorax

• common name: cats, dogs, rabbits “walking dandruff”

• location: keratin layer of skin or fur; non burrowing

• detection: examine dorsal midline and head; cellophane tape; flea comb onto black paper

• treatment: selamectin, milbemycin, ivermectin, lyme sulfer dip

tick characteristics

• blood sucking

• dorsoventrally flattened

• Ixodidae = hard ticks; have hard dorsal shield called scutum

• argasidae = soft ticks

• acariasis = infestation of ticks/mites

• not species specific

tick chelicerae

2 cutting/lacerating organs in head

tick hypostome

penetrating anchor like organ

tick pedipalps

leg like accessory appendages

argasid

• soft ticks

• infest large animals

• no scutum; head is ventrally located

• resistant to desiccation; live several years

tick paralysis

• affects humans, domestic animals, wild animals

• paralysis and respiratory failure

• Dermacentor saliva from female = toxic

• remove tick as soon as possible

Ixodes scapularis

• common name: deer tick / black legged tick

• host: dogs and humans

• from Ohio river valley / Eastern US; live in vegetation until attach to host

• vector for: babesia microti, tularemia, borrella burgdorferi (Lyme), ehrlichiosis

• “sticky”

• LYME DISEASE

Rhipicephalus sanguineus

• common name: brown dog tick, kennel tick, cattle fever tick

• host: dogs

• vector for: bebesia canis, ehrlichia canis, bovine theileriosis, babesiosis, anamplasmosis

• “fan head”

Dermacentor

• variabilis : american dog tick; vector for tularemia

• host: dogs and humans

• ornamental scutum

• “skin sticker” / “skin puncturer”

Amblyomma americanum

• common name: lone star tick

• white spot on scutum

• vector for: RMSF and tularemia

• “dull eye”

Haemaphysalis

• common name: rabbit tick, yellow dog tick, bush tick

• 3 host tick, leave host after each blood meal

• vector for: babesiosis, anaplasmosis, canine babesiosis

Otobius megnini

• soft tick

• common name: spinose ear tick

• hosts: stock, dogs, humans

• larval and nymph stage: suck blood in external ear canal

• adults in dry protected places

• backward facing spines

• nymph stage = violin shape

Argas persicus

• soft tick

• common name: fowl tick

• host: birds

• location: in cracks and crevices of poultry houses

• feed at night once a month

• causes: loss of productivity, restlessness, anemia, rickettsia