Parasitology -> Arthropods Flashcards
What orders compose the class Insecta?
Siphonaptera (fleas)
Phthiraptera (lice)
Diptera (flies)
Hemiptera (true bugs, bed bugs, kissing bugs)
Coleoptera (blister beetles)
Lepidoptera (urticating caterpillars)
Hymenoptera (bees, wasps, ants)
What order composes Class Arachnida?
Acari (ticks and mites)
How do insects differ from ticks and mites?
Insects have 3 body parts and 6 legs
Ticks and Mites have 2 body parts and 8 legs as an adult
Where do parasitic arthropods typically harbor pathogens?
In the salivary glands
What are the two types of life cycles of class Insecta?
Simple/Incomplete metamorphosis: immature stages look like small adults
Complex/complete metamorphosis: marked difference in morphology and structure between adults and immature stages
What is the insect of Order Siphonaptera with the most veterinary importance? List common features.
Fleas
Macroscopic, brown, wingless, laterally compressed, complex metamorphosis
What hosts do Ctenocephalides felis prefer?
Hosts: dogs, cats, ferrets, occasionally other animals
Most common flea of cats and dogs and is found worldwide
Do adult of Ctenocephalides felis spread from host to host?
No, once an adult is on a host, it is considered a permanent ectoparasite that will feed as soon as it finds a host
After an adult female of Ctenocephalides mates, how long will it take for her to start laying eggs?
24 hours
Describe characteristics of Ctenocephalides felis larva and what they require to develop
Larva is slender, white, 2-5 mm, and may have dark appearance from blood ingestion
They require the ingestion of flea feces, and prefer high humidity
Describe characteristics of Ctenocephalides felis pupa
The larva forms a sticky cocoon in which debris stick for camouflage
Adult can stay in pupa for up to 6 months, pupa is very tough and is not killed by pesticides
Roughly how long does each stage of the Ctenocephalides felis life cycle last under perfect conditions?
Egg hatching -> 2 days
Larva -> 6 days
Pupa -> 6 days
~14 days total
Eggs compose 50% of an infection
What is the clinical importance of Ctenocephalides felis?
Hypersensitivty rxn to saliva antigens -> flea allergy dermatitis
Range of pruritus and hair loss
Hot spots
Tapeworm vector
Anemia
What is the significance of rodent fleas?
Usually host specific, but will bite dogs/cats if given the opportunity
Vector of Yersinia pestis
What is the typical host of the sticktight flea (echidnophaga gallinacea)
Birds -> female stays attached
What is the most medically important species of order phthiraptera? List general characteristics
Lice
small, wingless, dorsoventrally flattened, can be white, gray, or brown
What are the two types of lice and what differentiates them?
Anoplura: sucking lice, only in mammals
Mallophaga: chewing lice, mammals and birds
Where do lice spend their life cycle? How long does this take
Lice spend their entire life cycle on the host with eggs glued to feathers or hairs
Life cycle takes about 4 weeks
How are lice often transmitted?
Direct contact or fomites
Why would we see an increase of lice in the winter in animals housed outdoors?
Animals huddle together, coat and body temp is favorable, potential cause of increased stress
Are we concerned about disease spread through lice in the US?
No, they are an insignificant vector here
In what animals are lice infestations common?
Typically seen in food animals, wild birds, and wild mammals
What are common features of the order diptera?
Adults have 1 pair of membranous wings
Undergo complete metamorphosis
Most have no parasitic stage
What is the clinical relevance of Musca domestica (housefly)
They aren’t parasites, but can interfere with normal behavior and can serve as mechanical disease vectors
lay eggs in decaying organic material
What is the clinical relevance of Musca autumnalis (face fly)
Females eat secretions (especially tears) for protein
Eggs laid in FRESH manure
primarily affect ruminants, horses
importance: fly worry, irritation of eye mucosa, transmission of moraxella bovis (pink eye)
Where do Haematobia irritans (horn fly) spend their life cycle and what part of the animal do they prefer?
Adults are resident parasites that spend all their life on the host
The flies prefer to sit on the dorsum (ventrum when hot) of primarily cattle
Where do horn flies lay their eggs and how long does their life cycle typically take?
Horn flies lay their eggs in fresh manure, and their life cycle can be complete in 10-12 days
What is the clinical significance of the horn fly?
They cause fly worry and fly bite dermatitis
They can carry bacteria that cause mastitis
Most important external parasite of cattle in the US
What is the life cycle and important of Stomoxys calcitrans (stable fly)
resemble house fly, important biting fly
Life cycle: visit host 1-2 times a day and bite lower body, legs, and feet, lay eggs in DECAYING matter and takes about 28-30 days to complete cycle
Importance: FW, FBD, not important disease vector
What is the life cycle and importance of family Tabanidae (horse, deer fly)
Large flies, stout body
Life cycle: lay eggs near water
Importance: annoyance, painful bites, mechanical vector of disease
What is the life cycle and importance of culicidae (mosquitoes)?
Life cycle: lay eggs in water, variation between species in egg preference
Importance: region is important, FBD, FW, disease vector
What is the life cycle and importance of Simuliidae (black flies, buffalo gnats)?
Life cycle: lay eggs in rapidly moving water
Importance: intense FW, can cause stampedes, FBD, disease vector, but limited in US (avian hemoprotozoa, EEE, vesicular stomatitis
What is the importance and life cycle of Culicoides spp (no-see-ums, midges)?
Very tiny (control)
Life cycle: larvae in moist soil or water
Importance: FW, FBD in horses (sweet itch), transmits bluetounge, some nematodes
What are distinguishing features of Hippoboscidae? How does this differ from other families?
Adults have a flat body, most common species (Melophagus ovinus) is wingless, includes “flat flies.”
Sheep and goat “ked”
What are 3 methods of fly control?
Mechanical
Manure control
Pesticides
What is myiasis?
Any infection due to the invasion of the tissues or cavities of the body by dipterous insects
What are the two types of myiasis?
- Cutaneous myiasis: fly strike, maggots
- Internal myiasis: grubs, warbles, bots
What type of larvae primarily cause fly strike (cutaneous)? What type of parasites are they?
Larvae of blow flies (Calliphorids) -> filth flies
Larvae are facultative parasites
What is the typically life cycle of fly strike causing larvae?
Eggs are laid in decaying organic material, but larvae feed on necrotic material
They pupate on the ground and adult flies emerge
Females are attracted to wound secretions
How is myiasis by fly strike larvae typically diagnosed, treated, and prevented?
Diagnosis: finding maggots
Treatment: remove maggots
Prevention: wound spray and do procedures before fly season
How does fly strike caused by Cochliomyia hominivorax (screw worm) differ from that caused by blow flies?
The larvae is an obligate parasite and requires living tissue, producing much more sever disease
Sterile male release program control method
What are distinguishing features of fly larvae that cause internal myiasis?
larvae are called bots, grubs, and/or warbles
adults are hairy and resemble bees
larvae are OBLIGATE internal parasite, then leaves to pupate in the environment
What is the life cycle of Gasterophilus spp. (horse bots)?
Eggs are laid on face or legs of equids, eggs hatch and move to mouth where they move to stomach for 10-12 months, pass out in manure and pupate in soil
Adult does not feed
What are clinical signs associated with Gasterophilus spp? How is it typically diagnosed and treated?
Not very pathogenic, so no specific clinical signs, but there can be rare ulceration or perforation of stomach
Diagnosis: see flies, eggs on legs
Treatment: annual treatment in fall, eggs/larvae removal
What is the life cycle of Cuterebra spp. (rodent bot flies)?
Common parasite of rodents, rabbits
Eggs laid near burrows, along trails
Larvae is picked up by host, develop in SQ host and then pupate on ground
What are clinical signs associated with Cuterebra spp (rodent bot flies)? How is it treated?
Clinical signs: lump observed that develops an opening, may lead to secondary infection
Treatment: careful removal
Dogs/Cats may pick up
What bugs of veterinary importance make up Order Hemiptera?
Bed Bugs (Cimex spp.)
Kissing bugs (triatomid bugs)
