Arthropods - Details Flashcards
Bot Flies
Also known as?
Larval Dipterans
Bot = Larvae = Maggot
Bot Flies
General Characteristics
- Larvae develop in animal host.
- Larvae are called bots.
- Larvae can infect wide variety of domestic animals.
- each one very host & site specific.
- Causes a disease called myiasis.
Bot Flies
Facultative Myiasis
Facultative Myiasis
- Fly larvae are usually free living but can become subcutaneous.
- Include Musca domestica, the blow flies, & flesh flies.
- Usually due to an open wound on host animal.
- Adult fly will lay eggs on blood on open wound.
- Larvae hatch & feed on dead cells, secretions, & debris.
- not on living tissue
- this is known as fly strike or strike.
- Maggots can create tissue cavities up to several cm in skin.
- filled with maggots.
- Infested animal can die from shock, infection, intoxication.
- Lesions give off a peculiar & distinct smell.
Bot Flies
Obligatory Myiasis
Obligatory Myiasis
- Fly larvae would NOT survive w/out parasitizing host.
- Include the other skin bots, stomach bots, and nasal bots.
Cuterebra spp. What animal(s) does it infect?
Rabbit, Squirrel, Mice, Rat, Chipmunk, sometimes Dog & Cat.
*rodents are usual host.
Cuterebra spp.
Life Cycle
- Adult lays eggs near entrance to rodent burrows.
- 1st stage larva hatches & can enter body orifices or wounds of another animal.
- Pets contract while inspecting rodent burrow
- most common sites in pets: neck & head. - Larvae mature in subcutaneous lesion in ~1 mo
- Larvae leave host & pupate on ground.
- Adults emerge from pupae.
- Adults are rarely seen.
- do NOT have mouth parts, do NOT feed.
- only live long enough to reproduce.
Cuterebra spp.
Symptoms & Disease
Creates a characteristic lesion on host.
- swollen, round, cyst-like.
- has a fistula, or central pore.
- acts as air hole for larva inside.
- Can also form lesions in cranium, anterior eye chamber, & throat.
- Vet must enlarge hole & carefully extract.
- crushing larva: animal may day from anaphylaxis.
- larva full of toxins.
- 2nd and 3rd stage larva usually in lesion.
- Extracted larva can be up to 3-4cm long.
Cuterebra spp.
Diagnosis
3rd stage larvae covered w/ black spines.
Hypoderma spp. What animal(s) does it infect?
Cattle
Hypoderma spp., Gasterophilus spp., Oestrus ovis
General Characteristics
Adults are heavy & resemble honeybees.
Hypoderma spp.
Life Cycle
- Adult lays eggs (1mm) on hair shaft of cow.
- Eggs hatch and larvae penetrate skin.
- Larvae wander through skin, esophagus, or spinal column region until they reach the subcutaneous tissues of the back.
- In the back, larvae create breathing holes & characteristic lesions.
- Eventually fall to ground & pupate.
Hypoderma spp.
Symptoms & Disease
As with Cuterebra spp:
- the larvae must be carefully extracted.
- full of toxins.
Gasterophilus spp. What animal(s) does it infect?
Horses
Gasterophilus spp.
Life Cycle
- Late summer / early fall adults lay eggs on hairs of horse.
- egg laying is very annoying to horse.
- can even cause horse to panic. - Horses lick eggs off hair.
- 1st stage larvae penetrate mucosa of mouth & lips.
- Penetrate the mucosa & migrate to stomach.
- Larvae remain attached to stomach lining for 10-12 months.
- up to 2 cm long.
- have hooks & spines. - Larvae pass out of host feces in spring.
- Pupate on the ground for a few weeks.
- Adult emerges from pupa.
Gasterophilus spp.
Diagnosis
- Seeing adult flies around horses.
- Seeing eggs on hair.
- seeing larvae in feces.
Oestrus ovis What animal(s) does it infect?
Sheep
Oestrus ovis
Life Cycle
- Adult lays eggs in nostrils of sheep.
- Larvae develop in nasal cavity & sinuses.
- are white, yellow, or brown, usually dark brown.
- can be up to 3 cm long.
- Larvae fall out of nostrils and pupate on the ground.
Oestrus ovis
Symptoms & Disease
Produce a respiratory myiasis in sheep.
- Head-shaking.
- Snorting and sneezing.
- excess nasal mucus.
- respiratory distress.
Order Anoplura
Also known as?
Sucking Lice
Order Anoplura
General Characteristics
- Larger of the 2.
- Head narrower than thorax.
- Mouth parts for piercing & sucking.
- Do NOT parasitize birds or cats.
- most other domestic animals/humans.
Order Mallophaga
Also known as?
Chewing or Biting Lice
Order Mallophaga
General Characteristics
- Smaller of the 2, essentially microscopic.
- Usually yellow.
- Have a large rounded head.
- wider than thorax.
- Mouth parts for biting/chewing.
- All bird lice are Mallophaga.
- birds often pick off and ingest them.
- Feed off epidermal tissues & materials.
- ex: keratin
- not harmful, just annoying.
Lice (Anoplura & Mallophaga)
General Characteristics
Some of the most prolific ectoparasites of domesticated & wild animals.
- Flat, wingless, insects.
- Three body parts:
- Head – with mouthparts.
- Thorax – with 3 pairs of legs.
- Abdomen – contains repro & digestive organs.
- Spend their entire lives among the hair/feathers of host.
Lice (Anoplura & Mallophaga)
Life Cycle
Entire life cycle takes 3-4 weeks.
Eggs
- called nits.
- are securely attached to hair/feathers of host.
- oval, white
- tiny (0.5 to 1 mm)
- have operculums that pop open to hatch the nymph.
Nymphs (juveniles)
- hatch from eggs ~5 to 14 days after being laid.
- look very similar to adult.
- smaller, no repro organs.
- molt 3x before growing to adult.
Adults
-nymph becomes adult in 2-3 weeks.
Lice (Anoplura & Mallophaga)
Symptoms & Disease
Disease/Symptoms
- called pediculosis
- infected w/Lice.
- usually more of a nuisance than threat to host.
- do not serve as vectors or ih’s.
- except human louse.
- takes many lice to drain host of vitality.
- heavily infested animals may show signs of illness:
- sucking lice can cause severe anemia in host.
* fatalities can occur in young animals - up to a million lice can be on a single animal.
- more susceptible to other diseases/parasites.
- sucking lice can cause severe anemia in host.
Transmission
- usually by direct contact.
- long fomite life for all stages.
Lice (Anoplura & Mallophaga)
Diagnosis
- finding nits on hair/feather or lice on host.
- use morphology of adult to id.
- also use host specificity to id.
- each type is VERY host specific.
- usually can only distinguish it as a sucking or biting louse.
- that +knowledge of host is enough to id.
Linognathus spp. What animal(s) does it infect?
Cattle, sheep, goats, dogs, foxes.
Polyplax spp. What animal(s) does it infect?
Rats, mice.
Pthirus What animal(s) does it infect?
Humans, Dogs (not normal host)
Pthirus
General Characteristics
In humans:
- on pubic hair, armpits, perianal, mustache, beard, eyebrows, eyelashes.
- extreme itching & dermatitis.
- entire family may be parasitized at once.
- spread by fomites.
- sometimes family dog is euth because he is thought to be reservoir. NOT TRUE!!
Pediculus spp. What animal(s) does it infect?
Humans, rarely dogs.
Trichodectes canis What animal(s) does it infect?
Dogs
Trichodectes canis
General Characteristics
- may be IH for Dipylidium caninum.
- a wintertime problem.
- skin irritation, pruritis, licking, biting, alopecia.
Felicola subrostratus What animal(s) does it infect?
Cats
Felicola subrostratus
General Characteristics
-symptoms same as for Trichodectes spp. on dogs.
Cuterebra spp.
General Characteristics
- Larvae are subcutaneous or may be ingested.
- Dogs & Cats are abnormal host.
