Ectoparasites: Identification and Treatment for Animals

+ Order: Hymenoptera Ants, Bees, Wasps, Hornets Can’t do a lot with these If one of these is suspected to be causing problems, try to collect one in 10% formalin or ethyl alcohol and send to an entomologist for identification Important to get the right identification +...

+ Order: Hymenoptera Ants, Bees, Wasps, Hornets Can’t do a lot with these If one of these is suspected to be causing problems, try to collect one in 10% formalin or ethyl alcohol and send to an entomologist for identification Important to get the right identification + Order: Hemiptera “True Bugs” Most adults have 2 pairs of wings Reduviid bugs Visit host frequently for blood meal Intermediate Host for the blood parasite Trypanosoma cruzi Bed bugs Dorsoventrally flat and wingless Usually infest homes Visit host off and on to get a blood meal Mostly a human parasite If suspected, collect and send to an entomologist + Fleas Laterally compressed Wingless Large powerful hind legs for jumping Piercing/sucking mouth parts Siphon-like Over 2000 species of fleas Vectors of several diseases: Bubonic Plague Tularemia + Fleas Ctenocephalides felis & C. canis o Most common flea on dogs and cats o Intermediate host for Dipylidium caninum Echidnophaga gallinacea o “Stick-tight flea” of poultry o Common flea of chickens and guinea fowl, but may also feed on dogs and cats o Unique feeding habits o Female flea inserts mouthparts into the skin of the host and remains attached at that site. May resemble a tick. Pulex irritans - human flea Has been recovered from dogs and cats especially in the southeastern United States + Fleas Not common parasites of horses or ruminants If large animals are in barns with lots of feral cats, they may get them Prefer their main host but will feed off of another one if hungry Flea saliva is antigenic & irritating. It causes intense itching and hypersensitivity which is known as: Flea allergy dermatitis Infestation usually obvious Flea Frass= Flea feces= flea dirt Digested blood Adults seen grossly Environmental control is very important, but can be very difficult. Client education is key! + Fleas Flea stages o Adult o Female flea lays eggs o Flea eggs- tiny smooth pearls, non-sticky o Deposited on host o Fall off and develop into larvae in the environment o (Salt shaker) o Flea larvae Occasionally found on animal’s bedding and furniture Maggot-like with a head capsule and bristles Feed on organic debris including adult flea feces Larvae spin cocoons and molt into pupae in cocoons Laboratory Procedures 6th ed. Pages 327-329 (Lifecycle on page 328) + Orders: Mallophaga and Anoplura (Lice) Mallophaga = chewing or biting lice Feed on epithelial debris and can move rapidly over the host. Yellow color generally. Broad, rounded head Anoplura = sucking lice Sucking lice feed on blood and move slowly on the host. They are larger than chewing lice. Red to gray color depending on the amount of blood ingested from the host. Long, narrow head SPECIES SPECIFIC Dorsoventrally flat and wingless 3 Body Parts Head, thorax, abdomen Laboratory Procedures 6th ed. Pages 329-330 + Lice Common species: Mallophaga vs. Anoplura Dog Anoplura: Linognathus setosus Mallophaga: Trichodectes canis Cat Anoplura: None Mallophaga: Felicola subrostratus Horse Anoplura: Haematopinus asini Mallophaga: Damalinia equi Cow Anoplura: Haematopinus vituli, Haematopinus eurysternus, Haematopinus quadripertusus, Solenopotes capillatus Mallophaga: Damalinia bovis Full list of hosts and species in Laboratory Procedures 6th ed. Page 329 + Lice Egg o Oval & white. Called a nit o Glued to hair or feathers of host o Hatch 5-14 days after laid Nymph o Same appearance as adult o Smaller and lacks functioning reproductive organs and genital openings o 3 stages each progressively larger than before o Entire nymphal stage lasts 2-3 weeks Adult o Has functional reproductive organs o Takes 3-4 weeks to complete a lifecycle o Nymph/adult will not live longer than 7 days if removed from the host Male and female copulate and the life cycle starts over again. + Lice Transmission: Direct contact, but can also occur via equipment contaminated with eggs, nymphs, or adults Old, young, malnourished are easy targets especially in overcrowded conditions and during the colder months Certain animals in herd will be infested while other animals are clean, no specific reason why Pediculosis: louse infestation Sucking lice cause anemia, whereas biting lice are irritating and disturbing to the animal. + Order: Diptera (Flies) Large, complex order of insects One pair of wings (flies, mosquitoes) Vary in developmental stages, size, and food source preferences Undergo complete metamorphosis Larvae develop in SQ tissue or internal organs causing myiasis Present 2 different pathological scenarios Laboratory Procedures 6th ed. pages 330-333 2 groups Female only feed on blood Biting gnats, mosquitoes, horse and deer flies Both male and female feed on blood Stable fly, horn fly, sheep ked, Face fly- mucus, tears, saliva + Blackflies & Midges Culicoides o Gnats o Biting midges (no see-ums) are small Culicoides species flies o Painful bite and suck blood o Horses often allergic to the bites Queensland itch, sweat itch, sweet itch, summer dermatitis o Intermediate host for Onchocerca cervicalis in the skin of horses o Transmit the Bluetongue virus of sheep Simulium o Blackflies, buffalo gnats o Characteristic humped back & broad, unspotted wings Serrated scissor-like mouthparts that inflict painful bites o Females lay eggs in well-aerated water (found near streams) o Intermediate hosts for Leukocytozoon + Sandflies Phlebotomus & Lutzomyia o Sandflies o Mothlike flies known for transmission of leishmaniasis and viral diseases o Females suck blood + Muscid Flies Muscid flies Housefly, Face fly Housefly and face fly do NOT suck blood, but are annoying because of their attraction to excrement and secretions Both are intermediate hosts for Habronema spp. & Thelazia spp. Mechanically transmit bacteria Stable fly (Stomoxys calcitrans) Often called the “biting housefly” Inflict painful bites and suck blood Stable fly spreads bacterial and viral diseases to cattle and horses Intermediate host for stomach worm of horses (Habronema) Has a bayonet-like proboscis that protrudes forward from the head Found worldwide; Very common in US where cattle are raised May feed on tips of dog ears Horn fly (Haematobia irritans) Inflict painful bites and suck blood Spend most of their lives on the host (cattle) + Muscid Flies (continued) When large numbers of stable flies attack dairy cattle, milk production can fall Beef cattle may refuse to graze in the daytime when they are attacked by large numbers of flies; as a result, these cattle do not gain the usual amount of weight These flies may feed on the tips of the ears of dogs with pointed ears, especially german shepherds. You may see a loss of hair and presence of dried, crusty blood on the ear tips. + Deer Flies & Horseflies Deer flies (Chrysops spp.) & Horseflies (Tabanus spp.) Large, heavy-bodied, powerful wings, large eyes Horseflies are larger than deer flies Adult flies lay eggs in the vicinity of open water Larval stages are often found buried deep in mud at the bottom of lakes and ponds Reciprocating, scissor-like mouthparts used to lacerate tissues Feed primarily on large animals (cattle & horses) If feeding on multiple horses, they may act as mechanical transmitters of anthrax, anaplasmosis, and equine infectious anemia (EIA) + Sheep Keds Melophagus ovinus o Known as Hippoboscids or Sheep keds o Dorsoventrally flattened and wingless o Hairy, leathery with a short, broad head o Legs are strong and armed with stout claws o Resemble ticks (some say they have a louse-like appearance) o Suck blood and spend their entire lives on the host (sheep) Will cause anemia, pruritis, and damage the wool o Laboratory Procedures page 241 + Flies that Produce Myiasis Blowflies, Flesh flies, & Screwworm flies Adults do not suck blood Deposit their eggs in decaying organic matter, septic wounds, or living flesh The larvae of Callitroga hominivorax & Wohlfahrtia opaca are the only primary invaders of LIVING tissue in North America Other members are attracted to septic wounds and are known as secondary invaders Botflies Gasterophilus spp. (Stomach of the horse) Hypoderma spp. (Dorsal subcutis of the cow) Cuterebra spp. (Subcutaneous tissues of host) Oestrus ovis (Nasal passages of sheep) Beelike flies; Adults do not feed Adult glues their eggs to the hairs of the host or deposits them at the entrance of animal burrows The larvae hatch and penetrate the skin of the host; Some migrate extensively through the host’s body and others develop locally Cuterebra are also known as warbles + Flies: Cuterebra Infest the skin Parasites of rabbits and rodents May also infest cats, dogs, and humans Larva are usually found in swollen, cystlike, subcutaneous sites, with a fistula (pore or hole) that communicates with the outside environment. The larva breathes through the hole. + Mosquitoes Anopheles spp., Aedes spp., Culex spp. o One of the most irritating Diptera o Females suck blood o Transmit numerous protozoal, viral, and nematode diseases to both animals and people. o May cause cattle to stop grazing or stampede o May cause significant anemia in domestic animals o Large numbers of mosquitoes may be produced from eggs that were laid in relatively small bodies of water. o Known for spreading malaria, yellow fever, and elephantitis among humans o Intermediate host for the canine heartworm (Dirofilaria immitis) + Order: Acarina (Ticks) Leathery bodies Dorsoventrally flattened in the unengorged state Head (capitulum) Organ of cutting and attachment Made of a penetrating, anchor-like sucking organ called the hypostome and four accessory appendages (2 cutting chelicerae & 2 pedipalps) that act as sensors and support the tick when fastened to the host’s body Most ticks are reddish or mahogany and inornate Seed ticks have 6 legs Adult ticks have 8 legs with claws on the ends May attach to and feed on 1-3 hosts during a life cycle and therefore are referred to as: one-host, two-host, or three-host ticks Lifecycle in Laboratory Procedures 6th ed. page 334 + Ticks FACTS: Can transmit many parasitic, bacterial, viral, and other diseases among animals and from animals to humans Blood-sucking arachnids Infestation of mites or ticks is referred to as Acariasis Most ticks do NOT tolerate: Direct Sunlight Dryness/Drought Excessive Rain Can live for a few years without blood Two types of ticks Hard ticks (Ixodidae) Soft ticks (Argasidae) + Hard Ticks (Ixodidae) Hard ticks are important vectors of protozoal, bacterial, viral, and rickettsial diseases Female tick saliva of some species is toxic and produces flaccid, which causes “tick paralysis” in animals and humans Tick species commonly associated with tick paralysis: Dermacentor andersoni (Rocky Mountain Wood Tick) Dermacentor occidentalis (Pacific Coast Tick) Ixodes holocyclus (Australian Paralysis Tick) Dermacentor variabilis (Wood Tick) Adults, larvae, and nymphs attach to the host and feed on blood. Eggs are deposited in the environment. Have a hard, chitinous covering (scutum) on the dorsal surface of the body May have grooves, margins, and notches (festoons) that are useful for identification purposes + Important Hard Ticks in North America Rhipicephalus sanguineus (Brown Ixodes scapularis (Deer Tick, Dog Tick) Blacklegged Tick) Rhipicephalus (Boophilus) Ixodes cookei (The Woodchuck annulatus (Blue Cattle Tick, Texas Tick) Fever Tick, American Cattle Tick, etc.) Ixodes pacificus (Western Dermacentor variabilis (American Blacklegged Tick) Dog Tick, Wood Tick) Dermacentor andersoni (Rocky Amblyomma americanum (Lone Mountain Wood Tick) Star Tick) Dermacentor occidentalis (Pacific Amblyomma maculatum (Gulf Coast Tick) Coast Tick) Dermacentor albipictus (Winter Haemaphysalis leporispalustris Tick) (Rabbit Tick) + Soft Ticks (Argasidae) Lack a scutum Mouthparts are not visible from the dorsal surface Lateral edges of the body are rounded The females feed often and eggs are laid OFF the host More resistance to desiccation than hard ticks Can live for several years in arid conditions Three species of veterinary importance: Argas persicus (Fowl Tick or Poultry Tick) Otobius megnini (Spinose Ear Tick) Ornithodoros spp. + Argas persicus Fowl or Poultry Tick Live in cracks and crevices of poultry houses and feed at night about once a month Cause restlessness, loss of productivity, and severe anemia Vector for bacterial and rickettsial diseases of birds + Otobius megnini Spinose Ear Tick Occurs on housed stock, dogs, and even people Only the larval and 2 of the nymphal stages are parasitic Live in the external ear canal and suck blood + Ornithodoros spp. Live in sandy soils, primitive housing, or shady areas around trees O. coriaceus is known to transmit the agent of foothill abortion in California + Mites Arachnids that occur as parasitic and free-living forms Some act as intermediate hosts for cestodes Most parasitic mites are obligate parasites and spend their entire life cycle on the host Produce the dermatologic condition referred to as mange Most mite infestations are transmitted through direct contact with an infested animal Burrowing mite infestations are diagnosed with deep skin scrapings at the periphery of lesions A few species found on birds and rodents live off of the host and visit the host only to obtain a blood meal Dermanyssus gallinae Ornithonyssus bacoti + Mites Sarcoptiform Mites Produce severe dermatologic problems and severe pruritus Barely visible to naked eye (grain of salt) Round/oval body shape Legs with pedicels or stalks at the tip Pedicels may be long, short, straight, or jointed At the tip of each pedicel may be a tiny sucker + Sarcoptiform Mites Two basic families of sarcoptiform mites: Sarcoptidae (burrowing mites) burrow or tunnel within the epidermis Sarcoptes scabiei Notoedres cati Cnemidocoptes spp. Trixacarus spp. Psoroptidae (non-burrowing mites) live on surface of skin or within the external ear canal Psoroptes spp. Chorioptes spp. Otodectes cyanotis + Mites Sarcoptidae Tunnel into the superficial layers of the epidermis and feed on tissue fluids Infestations begin as localized areas of inflammation and hair loss, but they spread rapidly and become generalized The female deposits 40-50 eggs over a 10-15 day period, then she dies Larvae emerge from the eggs within 3-10 days and exit the tunnel to the skin surface Larvae molt into the nymphal stage Nymphs become sexually active adults within 12-17 days The life cycle starts over + Sarcoptes scabiei Sarcoptic mange “Scabies” Zoonotic and very contagious Can affect most animal species, including people, but is most common on dogs and pigs Characterized by hair loss and intense pruritus (this can result in self-mutilation) Lesions are crusty and scaly and the skin may become thick and wrinkled Each animal species has its own variety of S. scabiei and cross- transmission does not occur Temporary infestation may take place without colonization of the skin + Notoedres cati Notodectic mange Feline scabies mite Zoonotic Occurs in cats and occasionally rabbits Found mainly on the ears, back of the neck, face, and feet Characterized by lesions with a yellowing crust + Cnemidocoptes spp. Scaly leg mite Budgerigars and parakeets (C. pilae) Poultry (C. mutans) C. pilae tunnels under the superficial epidermis of the feet, cere, and beak while C. mutans concentrates on the feet Produces a yellow to gray-white mass that resembles a honeycomb The parasites pierce the skin that underlies the scales, which causes an inflammatory exudate that hardens on the surface This condition may be disfiguring + Trixacarus caviae Burrowing mite of guinea pigs Lesions include dry, scaly skin, with pruritus, alopecia, and dermatitis Deep skin scrapings are needed to diagnose + Sarcoptiform Mites Psoroptidae Entire 5-stage life cycle is spent on the host Adults (8-legs) breed on the skin surface The female produces 14-24 oval, shiny white eggs that hatch within 1-3 days Larval (6-legs) and nymphal stages may last 7-10 days The life cycle is completed in about 10-18 days In favorable conditions: Mites can live off the host for 2-3 weeks or longer and eggs may remain viable for 2-4 weeks + Psoroptes spp. Psoroptic mange P. cuniculi (Rabbit ear mite) Affects rabbits, horses, goats, and sheep P. ovis (sheep), P. bovis (cattle), P. equi (horses) Scabies mite Reportable disease in large animals Important in sheep. The mites pierce the skin with their mouthparts causing vesicles to develop with crusting and intense pruritus Infested sheep constantly rub against things to scratch This mite severely damages wool + Chorioptes spp. Foot and Tail Mite or Itchy Leg Mite Affects horses, cattle, goats, and sheep Mites are found on the surface of the skin, particularly the lower hind legs, flanks and shoulders… and frequently on the tail of cattle They puncture the skin, causing serum to ooze. Thin crusts of coagulated serum form on the skin surface. The skin eventually thickens and wrinkles. + Otodectes cyanotis Ear Mites Affects dogs, cats, and ferrets Transmitted through direct contact with an infested animal Highly contagious Often causes the animal to shake its head and scratch its ears Aural hematomas may develop An ear swab can be used to diagnose + Nonsarcoptiform Mites Lack pedicels or stalks on their legs Demodecidae (burrowing mites) live in the hair follicles and sebaceous glands Demodex spp. + Demodex spp. Demodectic mange Burrowing mites that live in the hair follicles and sebaceous glands Affects domestic animals and humans; Considered part of the normal fauna of most mammals Most common among dogs Can be localized or generalized Transmitted through direct contact Immunodeficiency is necessary for an infestation to become clinically apparent Characterized by hair loss, thickening of skin, and pustule formation Deep skin scrapings are needed for diagnosis Resemble “little cigars” or “alligators” + Trombicula spp. CHIGGERS Yellow to red 6 legs Larval stage is the only stage that parasitizes humans, domestic animals, and wild animals Transmitted by direct contact with the ground or foliage Attach firmly to the host and inject a digestive fluid that liquefies the host cells. The injected fluid causes the attachment site to itch intensely. + Fur Mites Cheyletiella spp. (Walking Dandruff) Lynxacarus radovskyi (Feline Fur Mite) + Cheyletiella spp. “Walking dandruff” Transmitted through direct contact from host to host Affects dogs, cats, rabbits Found on the surface of the skin and hair coat Large, visible with the naked eye Characteristic body shape resembling: A shield A bell pepper An acorn A western horse saddle The motile mites resemble large, moving flakes of dandruff Combing is used to diagnose + Lynxacarus radovskyi Feline Fur Mite Affects cats Transmitted through direct contact from host to host Found attached to the shafts of individual hairs on the back, neck, thorax, and hind limbs Combing is used to diagnose This mite may also affect humans who handle infested cats, producing a papular dermatitis