Veterinary Parasitology Arthropod Parasites - Review

Melanie Buote DVM, DACVP, PhD Candidate Office: 3319 North Annex, Office phone #620-5106

Cell phone #628-5915 mabuote@upei.ca

Outline Protozoan parasites transmitted by arthropods (1 lecture)

I. Hemoflagellates 1. Trypanosomes 2. Leishmania

II. Piroplasms 1. Babesia 2. Cytauxzoon

III. Malarias 1. Plasmodium 2. Leucocytozoon

Arthropods (5 lectures)

I. Arachnids (2 lectures) 1. Ticks 2. Mites

II. Insects (3 lectures) 1. Lice 2. Fleas 3. Flies 4. Myiasis

Protozoan parasites transmitted by arthropods

Piroplasms Babesia

Cytauxzoon

Hemoflagellates Trypanosoma

Leishmania

Malarias Plasmodium

Leucocytozoon

Trypomastigotes in blood

Amastigotes in macrophages

Merozoites in RBCs

Merozoites in RBCs (& mø)

Merozoites in RBCs

Merozoites in RBCs, round & elongate gametocytes in blood

Protozoan parasites transmitted by arthropods

Piroplasms Babesia*

Cytauxzoon*

Hemoflagellates Trypanosoma

Leishmania

Malarias Plasmodium*

Leucocytozoon*

Nagana Chronic ill thrift

Cutaneous & Visceral Granulomatous inflam

Anemia > cerebral congestion

Pancytopenia, histiocytic inflam

Anemia, fatal in naive species

Anemia, hepatosplenomegaly

Chagas CHF

*RBCs are infected → Anemia!

Protozoan parasites transmitted by arthropods Protozoan Vector Host Disease

Trypanosoma congolense

Tse tse fly (Glossina sp.)

African cattle Bovine trypanosomiasis

Trypanosoma brucei brucei

Tse tse fly (Glossina sp.)

African cattle Nagana

Trypanosoma cruzi Triatomine (kissing) bug (Triatoma sp.)

Dogs Chagas Disease

Leishmania donovani complex

Phlebotomus sandfly Lutzomyia sandfly

Dogs Leishmaniasis

Babesia bovis Ixodid tick (Rhipicephalus appendiculatus)

Cattle Bovine babesiosis

Babesia gibsonii Ixodid tick (Rhipicephalus sanguinensis)

Dogs Canine babesiosis

Cytauxzoon felis Ixodid tick (Dermacentor variabilis)

Cats (bobcats) Cytauxzoonosis

Plasmodium relictum Culicine mosquito (Culex spp.)

Birds Avian malaria

Leucocytozoon simondi Simulium black fly (Simulium spp.)

Ducks & geese Turkeys Chickens

Leucocytozoonosis

Ticks – Important Genera

Ixodid (Hard) Ticks

1. Ixodes

2. Rhipicephalus (Boophilus)

3. Dermacentor

4. Amblyomma

Argasid (Soft) Ticks

1. Argas

2. Ornithodoros

3. Otobius

Ixodid Tick Identification

1. Scutum (shield) pattern – Each species has a unique pattern or color.

2. Festoons – Small areas separated by short grooves on the back

margin of the tick

– Helps distinguish all other ticks from Ixodes ticks, which lack festoons

3. Location and time of year – Based on your location in North America and the

time of year, only certain ticks will be active

Tick Identification

1. Scutum (shield) pattern – Each species has a unique pattern or color. – Ixodes ticks often have a black/brown solid colored scutum. – Dermacentor and Amblyomma ticks each have a patterned

scutum.

Tick Identification 2. Festoons

Ixodes spp. Lack Festoons

Anal groove in front of anus

Dermacentor spp. , Amblyomma spp., and Rhipicephalus spp. Prominent festoons*

Anal groove behind anus

Tick Identification

3. Location &

time of year

– Based on your location in North America and the time of year, only certain ticks will be active

http://www.tickencounter.org/current_tick_activity

Ixodid (Hard) Ticks – Important Genera

1. Ixodes • Inornate

• Anal groove in front of anus

• Long mouthparts (relatively)

2. Rhipicephalus (Boophilus) • Inornate

• Anal groove in behind anus

• Hexagonal basis capitulum

3. Dermacentor • Ornate

• Anal groove behind anus (not prominent)

• Rectangular basis capitulum

4. Amblyomma • Ornate

• Anal groove behind anus

• Mouthparts longer than basis capitulum

http://people.upei.ca/sgreenwood/html/arthropods.html

Tick Identification 2. Festoons

Ixodes spp. Lack Festoons

Anal groove in front of anus

Dermacentor spp. , Amblyomma spp., and Rhipicephalus spp. Prominent festoons*

Anal groove behind anus

Small areas separated by short grooves on the back margin of the tick

Argasid (Soft) Ticks 1. Argas persicus

– Ectoparasite of poultry – Feeds at night, – Hides in cracks & crevices during the day

2. Ornithodoros moubata – Infects domestic pigs – Vector of African Swine Fever Virus

(asfivirus)

3. Otobius megnini – Common parasites of livestock – Larval & nymphal stages – Found in the ear canal

Species Common Names 1 Host Tick 3 Host Tick

Ixodes scapularis Blacklegged Tick Deer Tick

Ixodes pacificus Western blacklegged tick

Rhipicephalus sanguineus Brown dog tick

Rhipicephalus (Boophilus) annulatus Blue cattle tick Texas cattle fever tick

Rhipicephalus (Boophilus) microplus Cattle Tick Southern cattle tick

Dermacentor variabilis American Dog Tick

Dermacentor andersoni Rocky Mountain Wood Tick

Dermacentor albipictus Moose tick

Amblyomma americanum Lone star Tick

Argas persicus Fowl Tick Chicken Tick

Multihost

Ornithodoros moubata Eyeless tampan Multihost

Otobius megnini Spinose ear tick

Pathogenesis 1. Anemia

– Blood loss in heavy infestations

2. Tick worry – Ill thrift caused by the loss

of blood, pain & swelling from the bite wounds, secondary infections & absorption of toxins

3. Dermatosis – Inflammation, swelling,

ulceration & itching – Induced by components of

tick’s saliva & mouthparts that remain in the wound

Pathogenesis 4. Paralysis (Tick Toxicosis)

– Some species of ticks’ saliva contain neurotoxins → disrupts motor nerve synapses in the spinal cord & blocks neuro-muscular junctions → ascending paralysis • a single tick can produce paralysis in dogs (and humans) • heavy infections are required to produce paralysis in cattle

– Clinical signs do not appear unless the tick has been feeding for approximately four (4) days

– Removing the tick(s) often result in dramatic recovery – http://www.youtube.com/watch?v=24DZEaUN7cc

5. Vectors – Ticks transmit a number of bacterial, viral & protozoal

pathogens – Pathogens may be passed

1. Transstadially = from larva to nymph & nymph to adult 2. Transovarially = from female to next generation

Lyme Disease

Mites – Important Genera

Genera of Mange Mites

1. Sarcoptes

2. Notoedres

3. Knemidocoptes

4. Psoroptes

5. Chorioptes

6. Otodectes

7. Cheyletiella

8. Demodex

Ectoparasites → Pruritus!

Mites – Important Genera Genera of Mange Mites

Dogs & Cats

1. Sarcoptes & Notoedres (cats only)

2. Otodectes

3. Cheyletiella

4. Demodex

Rabbits

1. Sarcoptes

2. Psoroptes

3. Cheyletiella

4. (Demodex)

Mites – Important Genera Genera of Mange Mites

Cattle, Sheep & Goats, & Horses

1. Sarcoptes

2. Psoroptes

3. Chorioptes

4. (Demodex)

Pigs

1. Sarcoptes

2. (Demodex)

Mange Mites → Pruritic Dermatitis Dogs Cats Rabbits Cattle Sheep & Goats Horses Pigs Avian

Sarcoptes

Notoedres

Knemidocoptes

Psoroptes

Chorioptes

Otodectes

Cheyletiella

Demodex

Pneumonyssoides caninum

Dermanyssus gallinae

Ornithonyssus sylviarum

Ruminant mange mites • Sarcoptic mites burrow into the skin.

– Short Legs

• Psorptic and Chorioptic mites are non-burrowing. – Long legs

• At the end of the legs of all three types are thin structures called pedicels which have a sucker at the end.

• The appearance of these pedicels is used to identify the type of mite. – The pedicels of the Psoroptes type of

mite are long and jointed. – Sarcoptic mites also have long pedicels

but they are not jointed. – The pedicels of Chorioptic mites are

short.

Psoroptes pedicels are segmented:

“P” is for parts

8. Demodex spp.

• Most Demodex spp. are considered normal mammalian fauna – Are acquired at birth by direct contact – Considered normal inhabitants of the skin (usually non-pathogenic)

• Overgrowth of normal mite fauna →development of patchy

hair loss +/- mild to severe dermatitis in dogs and (less commonly) in cats

• Exceptions (FYI): – Demodex sp. “cornei” (dogs) & D. gatoi (cats)

• Small, blunt-ended demodectic mites

– Disease is thought to be caused by the infestation itself rather than an overgrowth of mites

– Can be associated with pruritus in the absence of pyoderma – Contagious (vs. overgrowth)

1 Sarcoptes mite = Sarcoptic Mange 1 Demodex mite = Normal Flora Numerous Demodex mites = Demodectic mange

8. Demodex spp.

• Dogs – Demodex canis* (180 to 210 µm)

– Demodex injai (330 to 370 µm)

– Demodex sp. cornei (90 to 140 µm)

• Cats – Demodex cati* (181 to 219 µm)

– Demodex gatoi (81 to 115 µm)

– Demodex sp. (170-174 µm)

D. canis vs. D. injai D. cati vs. D. gatoi

*Prevalence is virtually 100%

8. Demodex spp. Two forms of canine demodecosis: 1. Localized demodecosis (90% of cases) • Focal areas of erythema & alopecia • Head, neck, & forelegs • No secondary problems • Most (90%) will resolve spontaneously

2. Generalized demodecosis (the other 10%) • Onset in dogs due to some underlying factor • Lesions spread from head to rest of body • Generalized erythema, alopecia, crusting &

scaling • Secondary infections can occur (i.e.,

pyoderma) resulting in oozing exudative lesions with severe crusting

• Severe cases are accompanied by a foul smelling putrid odor & are difficult to cure

Mites – Important Genera Genera of Mange Mites

Avian 1. Knemidocoptes

1. Knemidocoptes mutans * 2. Knemidocoptes gallinae* 3. Knemidocoptes jamaicensis 4. Knemidocoptes pilae

2. Dermanyssus gallinae*

3. Ornithonyssus sylviarum*

*Fowl Mites

3. Knemidocoptes spp.

Clinical Signs 3.1 Knemidocoptes mutans Scaly leg and face in domestic fowl • Chickens, turkeys, pheasants, and

other gallinaceous birds • Several raptor species • Mite burrows beneath leg scales

and causes them to loosen and rise → hyperkeratosis

FYI: 3.2 Knemidocoptes gallinae 3.3 Knemidocoptes jamaicensis 3.4 Knemidocoptes pilae

Dermanyssus gallinae & Ornithonyssus sylviarum Dermanyssus gallinae - Chicken Mite (= Red Mite) • A blood-sucking mite of poultry in wood-framed

houses • Mites are found on birds only when feeding (at night)

otherwise hide in nests, roosts & crevices

Ornithonyssus sylviarum - Northern Fowl Mite • The most important & common ectoparasite of the

poultry industry • Is also a blood-sucking mite, and is reddish-brown

after a bloodmeal • Remains on bird throughout life

• Fowl ticks (Argas persicus) Argasid (soft) ticks live in the

cracks and crevices of a poultry house. Ticks in various stages of development will feed on a host.

http://www.extension.org/pages/66149/external-parasites-of-poultry#.Uqt43SdoCYk

Lice – Pruritic Dermatitis

I. Anoplura (sucking lice - mammals) 1. Haematopinus

• Horses, Cattle, Pigs

2. Linognathus • Dogs, Cattle, Sheep (and Goats)

II. Mallophaga (chewing/biting lice) 1. Trichodectes

• Dogs

2. Felicola • Cats

3. Bovicola • Horses = Bovicola equi • Cattle = Bovicola bovis • Sheep = Bovicola ovis

4. Menopon • Poultry

Ectoparasites → Pruritus

Sucking Lice (Anoplura) • Head is narrower than thorax &

elongated • Adults 0.5 - 8 mm in length • Mouth parts are highly modified

– Composed of 3 stylets which form a set of fine cutting structures

• Hosts are placental mammals • “Crab-like” claws on the tarsus

– Cling to hairs of the host, – The diameter of the claw is related

to the diameter of the host’s hair shaft → host specificity

Chewing Lice (Mallophaga) • Heads are large, wider than thorax &

rounded • Usually 2 - 3 mm in length • Have mandibulate mouthparts typical

of chewing insects – Feed on feathers, hair, and skin – Some feed on blood

• Hosts are birds and mammals • The species that feed on birds

typically have 2 claws on the end of each tarsus; those that feed on mammals typically have just 1 claw

The Fleas

Common species

1. Ctenocephalides felis - cat flea - most dog and cat fleas in NA

2. Ctenocephalides canis - dog flea

3. Pulex irritans - human flea

4. Xenopsylla cheopis - Oriental rat flea

5. Echidnophaga gallinacea

- poultry “sticktight” flea

6. Ceratophyllus niger

- Western chicken flea

The Fleas – Order Siphonaptera

I. Order Siphonaptera = Fleas

• Ctenocephalides felis - "cat" flea

• Ctenocephalides canis - "dog" flea

The Fleas

1. Ctenocephalides felis - the cat flea

• The most important species on dogs & cats – 93% of fleas on dogs – 99.8% of fleas on cats

• The major cause of flea allergy dermatitis (FAD) • Ubiquitous & parasitizes a wide range of hosts

– cats, dogs, cattle & humans

• Sloping elongated front of head • Genal & pronotal comb • About 2.5 mm long • Life cycle completed in 12 - 14 days - 174 days

depending on conditions • Only a few fleas required to cause great misery to

host • One bite can cause allergic reaction in sensitized

host (FAD)

The Fleas → Pruritic Dermatitis Pathology • Flea bite dermatitis

– Low numbers = an annoyance – ↑ # of fleas → ↑ dermatitis – Heavy infestation

• Anemia and death

• Flea allergy dermatitis – Hapten in fleas’ saliva

• Antigenic when fixed to host protein

– Increased scratching or itchiness (pruritus) → pruritus-induced self trauma

– Loss of hair, hairs that appear broken, – Crusts and erosions, and pimple-like

bumps. – Thickened skin with darkened areas

can be seen in severe cases. – Hot spots sometimes can be seen

along the dog's back and tail base. • Circular, red, oozing, painful sores

– Can be perpetuated by a single flea!

Flea Control Host has: • Adults on body + eggs in hair or feathers

Environment: • Eggs + Larvae + Pupae + Adults

Majority of fleas usually in environment!

Integrated control program:

Includes the host AND the environment. 1. Control on host

– Dips, sprays, powders, shampoos, flea collars, and systemics

2. Clean up host’s environment • This step begins by laundering and steam

cleaning/vacuuming: – Wash pet bedding in hot water to kill flea larvae. If animals sleep

with family members, all bedding must be washed. – Steam clean or vacuum carpets thoroughly everywhere the

infested pet is allowed to roam.

• Use chemicals to treat environment – Residuals or knockdown, Insect growth regulators – Focus on locations where pets go in and out of the house, sleep

and rest, jump off beds, sofas and chairs, and spend time with family members.

The Fleas

Pathology

• Intermediate hosts

– Dipylidium caninum

– Dipetalonema reconditum

• Vectors

– Plague (Yersinia pestis)

– Typhus (Rickettsia typhi)

The Fleas

4. Xenopsylla cheopis - the Oreintal rat flea

• Genus of rodent fleas that attacks humans • Lacks combs • Has smoothly rounded head • A bristle in front of the eye • A vertical rod on the mesothorax (Pulex

does not) • Vector

– Yersinia pestis (Bubonic Plague) – Rickettsia typhi (Typhus )

The Flies

Adult Flies of Veterinary Importance 1. Culicidae - Mosquitoes 2. Simuliidae - Black Flies 3. Ceratopogonidae - Gnats & biting midges 4. Psychodidae (Phlebotominae) - Sand Flies 5. Tabanidae - Horse Flies & Deer Flies 6. Muscidae - House flies, Stable Flies & Horn Flies 7. Hippoboscidae – Sheep Keds (wingless flies) 8. Glossinidae – Tse tse flies

FYI: Descriptive features of Dipteran Familes: http://www.mdfrc.org.au/bugguide/display.asp?type=3

&class=17&subclass=&Order=7&couplet=0

The Flies Ways to control flies: • Regardless of the species of fly, an

integrated approach that incorporates sanitation, mechanical control, and the use of insecticides is the best strategy for fly control.

1. Sanitation: – Since manure and organic matter are

common breeding grounds for flies, regular removal of manure & organic matter will deter fly populations by reducing the number of eggs laid.

2. Mechanical control – Preventing accumulation of water and wet

areas reduces fly breeding. – Mechanical control of flies in buildings

through the use of screens.

3. Insecticides – Can be delivered by ear tags, dust bags,

oilers, sprays, pour-ons, and feed additives.

Fly Vector Veterinary Disease Transmission

Mosquitoes (Culex, Anopheles) Canine heartworm, avian malaria, West Nile virus, viral encephalitides

Black flies (Simulium) Leukocytozoonosis (poultry), onchocerciasis (cattle)

Gnats (Culicoides) Bluetongue virus, onchocerciasis (cattle), viral encephalitides, African Horse sickness

Sandflies (Phlebotomus = old world, Lutzomyia = new world)

Leishmaniasis

Horse & deer flies (Tabanid flies, such as Tabanus)

Bovine anaplasmosis, anthrax, tularemia, EIA virus, hog cholera virus, vesicular stomatitis

House flies (Musca domestica) E. coli, Salmonella, Shigella, Campylobacter, and Enterococcus; protozoan cysts; Habronemiass

Horn flies (Haematobium) Stephanofilarial dermatitis (cattle)

Tse tse flies (Glossina) African trypanosomiasis (cattle)

Pruritus of the tail in horses

1. Culicoides hypersensitivity “sweet itch”

2. Simulium hypersensitivity

3. Haematopinus asini (sucking louse)

4. Psoroptic mange

5. Oxyuris equi (pinworms)

The Flies 8. Keds - Family Hippoboscidae

Important Species

• Melophagus ovinus – a wingless blood-sucking continuous ectoparasite of

sheep & goats (a fly that doesn’t fly)

Morphology

• Tick-like in appearance

• 5-8 mm in length and brown

• Dorsoventrally flattened

• Wingless

• Strong claws – Cling to wool or hair

Sheep

• Sheep Keds – Melophagus ovinus

(5-8 mm)

• Pediculosis (Lice) – Bovicola ovis

– Linognathus ovillus

– Linognathus pedalis

(1-8 mm, most 2-3 mm)

• Mange – Psoroptes & Chorioptes

(~200-400 um = <0.5 mm)

X

The Flies - Myiasis

2 important groups of blow flies I. Screwworms (cattle)

1. Cochliomyia (New World) – Cochliomyia hominovorax ( 1° screw worm ) – Cochliomyia macellaria

(2° screw worm )

2. Chrysomyia (Old World)

II. Strike flies (fly strike in rabbits & sheep) 1-4. Lucilia, Phormia, Protophormia, Calliphora

4 Important Genera of bots and warbles:

1. Oestrus (sheep nasal bots) 2. Gasterophilus (horse bots) 3. Hypoderma (cattle grubs or warbles) 4. Cuterebra (rabbit bots)

The Flies – Myiasis 2. Bots & Warbles – Family Oestridae

Gasterophilus intestinalis

• Eggs – Hairs of forelegs → invade via

mouth (licking of legs)

• Bots – Cardiac region of the

stomach

Gasterophilus nasalis

• Eggs – Hairs of the intermandibular

skin → invade via mouth

• Bots – Pyloric region of the stomach

>>> duodenum

The Flies – Myiasis 2. Bots & Warbles – Family Oestridae

Gastric bots: The two species we typically encounter are G. nasalis and G. intestinalis. G. nasalis is farthest from the nose, G. intestinalis is farthest from the intestine.

Bots attach to the gastric lining above

the fluid line!

Hemimetabolous Incomplete development (egg, nymph, adult)

• Arachnida (ticks and mites)

• Phthiraptera (lice)

Holometabolous Complete development (egg, larva, pupa, adult)

• Siphonaptera (fleas)

• Diptera (flies)

“F” is for Full

1. Chelicera – Cut & pierce the host’s skin

2. Palps – Sensory, stabilization

3. Hypostome – Anchor

1. Mandibles (Jaws) – Used for cutting, tearing &

crushing

2. Maxillae – Used in food handling

3. Labium – Also used for food handling

Reminder!

• Final Lab Exam – Content: CUMULATIVE – Arthropod section: You only have to identify arthropod

parasites to the level of GENUS

• Written Final Exam = 4th Midterm

– Content: Protozoan parasites transmitted by arthropods and arthropod parasites (Dr. Buote’s lectures)

– You will have to be able to RECOGNIZE (i.e., multiple choice & matching) and RECALL (i.e., fill in blanks, short answer questions, and long answer questions) arthropod parasites to the level of SPECIES

Questions?