Arthropods Flashcards
What class, order, and family are mosquitoes, Cuterebra, and bottle flies?
- Class Insecta
- Order Diptera
- Family Culicidae
Which are the most prominent blood sucking dipterans?
Mosquitoes
What is the lifecycle of mosquitoes?
- Eggs
- larvae - 1st molt in 5-6d (3x total)
- Filter feeders
- Pupae: stage lasts 2-3d
- Non-feeding
- Adults: lifespan 6-7d, mate once
What are the 3 subfamilies of mosquitoes?

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How do you differentiate Anopheline vs. Culicine mosquitoes?
- Anopheline
- intermediate host/vector - Plasmodium spp.
- Culicine
- vector: Yellow/Dengue fever, West Nile Encephalitis
How do you control mosquitoes?
- Larvivorous fish (guppies, mosquito fish)
- ’Beneficial’ mosquito larvae - Toxorhynchinitine subfamily = predaceous
- stick mustard seeds - stick to larvae when try to eat
- draining breeding sites
What is facultative myiasis?
Blow flies or Bottle flies (calliphora, Phormia, Lucille)
- Normally, eggs deposited in garbage, feces, rotten carrion
- Occasionally, eggs deposited in contaminated wounds
- Early lesions = dermatitis, numerous maggots, pungent odor, inflammation
- Hosts: any mammal, vomit-drop feeders

Describe obligatory myiasis
Cochliomyia hominivorax, Cuterebra
- Larvae MUST use animal host to complete life cycle
- living tissue
- organs
- uncontaminated wounds
- soft tissue

Describe Cochliomyia hominivorax (primary screwworm)

- eradicated by sterile male release (50’s)
- Reportable (APHIS)
- affects any mammal - fresh, recent wounds, living tissue
- breed only once during life time
- cause toxemia, bacterial infections, death
How do you diagnose and treat C. Hominivorax?
- Dx: Larval ID (dark tracheal trunks that go all the way down), dermatitis, pungent odor
- Tx: remove larvae, treat secondary bacterial/fungal infections
Describe Cuterebra

- “Wolves, warbles”
- hosts: cats, dogs, rabbits, rodents
- Adults: non parasitic
- Larvae: darken with maturity
What is the life cycle of Cuterebra?
- Eggs deposited near entrance to burrow/nest - warmer months
- enter host
- migrate through host
- subcutaneous cysts produced - maturation 1 month
- pupate in soil
- adults emerge in spring
What is this parasite?

Cuterebra
Describe the pathogenesis of Cuterebra spp.
- cysts and swellings - secondary infections
- cutaneous
- eye, trachea, pharynx, upper resp tract, ear
- heals slowly
- larval migrations
- Cerebrospinal cuterebriasis - blindness, anorexia, lethargy, disorientation, circling, seizures
How do you diagnose and treat Cuterebra spp.?
- Dx: larval ID
- Tx:
- surgically remove larvae
- Fipronil, imidacloprid? (On haircoat)
- ivermectin, milbemycin, selamectin
- may kill larvae - migration
- +/- steroids?
What orders are lice?
- Anoplura and Mallophaga
What is the term for a lice infestation?
pediculiasis
Describe lice
- Small, wingless
- dorsoventrally flattened
- claw/crab-like legs
- permanent ectoparasites
- Stenoxenous - very host specific
- simple metamorphosis
What is the lifecycle of lice?
.

Which lice is which?

- Left - Mallophaga (chewing louse)
- wider head than thorax
- Right - Anoplura (biting louse)
- head smaller than thorax
Mallophaga lice feed on what species?
Birds and mammals
What are these two parasites?


Anoplura lice target which species?
ONLY mammals
Which two parasites are these?


What are the primary types of Anoplura lice?
- Linognathus setosus (dogs)
- Pediculus humanus humanus (body)
- Pediuculus humanus capitis (head)
- Pthirus pubis (pubic)
What are the main Mallophaga lice that we focused on?
Trichodectes canis and Felicola subrostratus
What are the treatments for lice?
- Selamectin
- Fipronil
- Imidacloprid
- Topical permethrin (dogs)
- Carbaryl shampoos, sprays, dips
Which parasite is a part of the order Siphonaptera?
Fleas
What is the term for a flea infestation?
Siphonapteriasis
What diseases are carried by fleas?
- Plague
- tularemia
- Dipylidium caninum
- Hymenolepsis nana
- A. Reconditium
Describe fleas
- Laterally compressed
- wingless
- ctenidia
- complex metamorphosis
- C/S: irritation, restlessness, anemia, FAD
What are the various types of fleas?

What are these?


What is this flea?


WHAT ARE THOSE?

- Left: Ctenocephalides felis (prominent whiskers)
- Right: Echinophaga gallinacea (flat face)
True or false: the majority of the life stages of fleas live off the host
True

Describe the life cycle of fleas
- Eggs are laid on host, fall off - hatch in 2-16d
- Larval stage (7-10d), 2 molts, 3 instars
- Covered in setae, feed on flea dirt (frass), susceptible to heat/desiccation
- Pupal stage (4d), larvae become coated in particles from environment
- Adults - mate once, begin feeding < 1 hr after colonizing host
Describe Flea Allergy Dermatitis

- Biting fleas introduce salivary proteins (antigens)
- Onset of FAD - 3-5 yrs old
- Lesions on LS region, caudal thighs, prox tail, ventral abdomen
- papules, crusts, alopecia, excoriation, erythema, hyperpigmentation
How do you control fleas?
-
Host-targeted insecticides
- IGRs, Adulticides
- Environmental insecticides
- Mechanical methods
What order are ticks in?
Acarina
What is the term for a tick infestation?
Acariasis or Otoacariasis
Describe ticks

- All stages feed on blood
- 2 families:
- Ixodidae
- Argasidae
- Simple metamorphosis: 1-, 2- or 3-host tick life cycles
Describe tick paralysis
-
Ascending, flaccid paralysis
- d/t neurotoxin in tick saliva
- Reversed with tick removal
- caused by the feeding female (over 40 species)
- 1st sign 5d after attachment
Describe the basic body division of ticks
- Capitulum
- Idiosoma
- scutum
- male v. Female
- festoons
- 8 legs: adults, nymphs
- 6 legs: larvae
What are the reportable diseases carried by ticks?
- Lyme
- Monocytic Ehrlichiosis
- Granulocytic Anaplasmosis
- RMSF
- Tularemia
What species of tick is this?

Amblyomma americanum larva- Lone star tick
Describe the life cycle of ticks

How do you differentiate male and female ticks?
- females - the scutum only partially covers the body

What are the methods of disease transmission for ticks? What is the difference between these two?
- Transstadial transmission: disease/pathogen acquired during one life stage stays with the tick and can be passed to another
- Transovarial transmission: disease/pathogen passed from female to developing offspring
Which ticks are a part of the family Ixodidae?
- Rhipicephalus sanguineus
- Ambylomma americanum
- Dermacentor variabilis
- Ixodes scapularis
Describe Rhipicephalus sanguineus

- Brown dog tick
-
Three host tick - mainly dogs (all 3 stages)
- common ears/between toes
- Throughout US
- Can cause tick paralysis
- Dz vector for
- Hepatozoon canis
- Babesia canis
- Erhlichia canis
- Rickettsia rickettsii (RMSF)
Describe the life cycle of R. Sanguineus

Describe Ixodes scapularis

- Black legged tick, Deer tick
- Three host tick - birds, small mammals, cattle, sheep, horses
- Southeastern to S. Central US, along East Coast
- Can cause tick paralysis
- Dz vector for:
- Borrelia burgdorferi Lyme)
- Babesia microti
- Anaplasma marginale
Describe the life cycle of Ixodes scapularis

How does the seasonal activity of I. Scapularis larvae, nymphs and adults differ?
- Larvae: July-Sept
- Nymph: May-Sept
- Adult: Oct-May
Describe Ambylomma americanum

- Lone star tick
-
Three host tick
- rodents, rabbits
- deer, cattle, horses, sheep
- Humans
- Can cause tick paralysis
- Distribution: southern US - early spring to late summer
- Dz vector for:
- Rickettsia rickettsii (RMSF)
- Francisella tularensis (tularemia)
- Ehrlichia chaffeensis
Describe Dermacentor variabilis

- American dog tick, wood tick
-
Three host tick
- Rodents, small mammals
- Dog (preferred), cow
- Distributed around most of the US
- Can causes tick paralysis
- Dz vector:
- Rickettsia rickettsii (RMSF)
- Anaplasma marginale
Which are these?


How do the markings on Ixodes ticks differ from the other ticks?

How do you control ticks?
- manual removal
- insectidices/acaracides
- dogs: afoxolaner, amitraz, Fipronil, fluralaner, pyrethroids (permethrin)
- cats: etofenprox, Fipronil, flumethrin
- Selamectin (dogs) - D. Variabilis
What order are mites a part of?
Acarina
Describe the general characteristics of mites
- Microscopic or barely visible
- pedicels (legs/stalks) - ID
- surface dweller or tunnel through skin layers
- larva - 6 legs; adult - 8 legs
- 2 body divisions
Describe Otodectes cynotis
- Ear mite
- Hosts: dogs, cats, foxes, raccoons, ferrets
- In external ear canal: surface dwelling
-
Short, nonjointed pedicels
- Females: suckers on leg pairs 1,2
- Males: suckers on all leg pairs
- Permanent parasite

What are the clinical signs of an Otodectes infestation?
- Thick, tarry exudate
- Host shakes head, scratches ear
- Infections of middle/inner ear can develop if untreated
- secondary bacterial/fungal infections: Staph/Malassezia
Dx: Swab of ear canal, otoscope
How do you treat Otodectes cynotis?
- Labeled (cats): ivermectin, milbemycin, moxidectin/imidacloprid, selamectin
- Labeled (dogs) selamectin
- Not labeled: doramectin, Fipronil, laners (sarolaner for dogs only)
Describe the characteristics of Demodex canis
- Follicle mite of dogs
- Host: Dogs
- D. Canis, D. Injai sp. cornei
- Cats: D. Cati, D. Gatoi, D. Sp.
- in hair follicles and adjacent sebaceous glands
- alligator/cigar shaped: adults 8 legs, larva 6 legs
- Permanent parasite
- Found in skin of most normal dogs
- D. Canis, initially on face of puppies
Which species is which?


Describe localized and generalized demodectic acariasis
Localized
- young dogs (usually <6mo)
- skin redness
- parital hair loss
- usually no itching
- commonly on face, around eyes, limbs
Generalized
- overgrowth? Underlying immune defect? Poor nutrition?
- more severe
- Large patches of alopecia
- secondary bacterial infections/pyoderma
Describe demodectic acariasis in cats
Localized
- Alopecia
- crusts
- scaling around face, neck, eyelids
- hyperpigmentation
Generalized
- Generally D. Cati overgrowth assoc. w/ underlying systemic dz
- D. Gatoi - cats pruritic, excessively lick/groom
- Not normally assoc. w/ underlying dz
- groin, ventral chest, limbs
How do you diagnose and treat Demodex canis?
- Dx: deep skin scrape, pustule and abscess contents, +/- fecal?
- Tx:
- localized: usually resolves spontaneously
- generalized: amitraz dip
- not approved tx: ivermectin, milbemycin, moxidectin (topical), laners (fluralaner for cats)
Describe Cheyletiella

- “Walking dandruff”
- hosts: dogs and cats
- may set up temporary residence on humans
- found in fur coat, keratin layer of dermis
- Surface dwelling, non-burrowing
- ID: bell-pepper shaped, mouthparts resemble hooks/horns
What are the clinical signs of “Walking Dandruff”?

- Asymptomatic to severe - dandruff, itchiness, reddened skin, hair loss
How do you diagnose and treat Cheyletiella?
- Dx: skin scrapings not necessary, scotch tape? Fecal?
- Tx: easily killed, most flea shampoos will suffice
- ivermectin, fipronil, selamectin
Describe Pneumonyssoides caninum

- Nasal mite
- hosts: dogs, other canids
- Direct contact
- Also travel via fleas, lice, flies
- survival off host
- Habitat: nasal passages and sinuses - non-burrowing, feed on keratin layer of epidermis
- ID: oval, creamy white, legs anterior half of abdomen
What are these little guys?

Pneumonyssoides caninum in nasal passages
What are the clinical signs of a Pneumonyssoides caninum infestastion?
- Reddening of mucosa, sneezing, head shaking, rubbing nose
- has been associated with bronchitis
How do you diagnose and treat Pneumonyssoides infestations?
- Dx: Microscopic ID - rhinoscopic exam, mucus/watery secretions from nose
- Tx: Milbemycin, ivermectin + selamectin, moxidectin/imidacloprid
Describe Notoedres cati

- Notoedric acariasis mite
- Hosts: cats, rabbits - zoonotic
- Mainly ears, back of neck
- Females burrow/tunnel in epidermis
- ID: round body, long nonjointed pedicels
- females: suckers leg pairs 1&2
- males: suckers leg pairs 1,2,4
Describe the clinical signs caused by a Notoedres infestation
- Persistent pruritus
- alopecia
- self mutilation
- hyperkeratosis
- epidermal flakes
- yellow crusts (face, neck)
How do you diagnose and treat Notoedres infestations?
- Dx: deep skin scrapings, fecal exam
- Tx: Selamectin, fipronil, ivermectin
Describe Sarcoptes scabiei

- Sarcoptes acariasis mite, Itch mite
- hosts: dogs, cattle, horses, sheep, goats, swine (rarely cats)
- Direct contact - highly transmissible
- Habitat - dogs: muzzles, eyes, ears, feet
- Females burrow/tunnel into epidermis
- males/larvae/nymphs: skin surface, near tunnel openings
Describe the clinical signs caused by Sarcoptes scabiei
- Irritation, itching, exudate, forms crusts
- Thickening of skin, alopecia
- severe cases result in death (large lesions)
How do you diagnose and treat Sarcoptes scabiei?
- Dx: deep skin scrapings, ID - long, non jointed pedicels, gray white, barely visible
- females - suckers leg pairs 1&2, males - suckers leg pairs 1,2,4
- Tx: treat all in-contact animals
- selamectin
- imidacloprid/moxidectin
- amitraz, benzyl benzoate, lime sulfur, phosmet, rotenone