Nematodes (Non-bursate)

Infective stage

• L2 in egg → ____________

ingested from the environment

Infective stage

• Larvae in tissue → ______________

driven by carnivorism

Infective stage

• L3 in vector → _____________

arthropod transmission

• ex. fly and mosquito

What are the basic characteristics of ascarids?

Roundworms

• live in the small intestine

• big fleshy worms (4-40 cm)

• direct life cycles

How are ascarids (roundworms) typically transmitted?

Environmental infective stage is L2 (in egg)

• requires ingestion of the larvated egg

What is special about ascarid eggs?

• spherical

• pitted, thick, protective shell

  • can be viable up to 5 years

Ascarid Hepatotracheal Migration

____ hatches in small intestine → _____ penetrates small intestine → hepatic portal blood → _______ → venous blood → ________ → lungs → _________ → swallowed → __________

• egg

• larva

• liver

• heart

• coughed up trachea

• back to small intestine

What is the purpose of hepatotracheal migration ?

It allows for the larva to mature

What are ascarid’s target organ?

lungs

• they want to be coughed up and swallowed to ultimately end up in the small intestine again

What are Toxocara canis ?

Roundworm of dogs

Toxocara canis

• life cycle : ______

• Definitive host : ______

• Paratenic host(s): ________

• Transmission : ___________

• direct

• dog

• possible; small mammals

• ingestion of larvated eggs or paratenic host, transplacental, transmammary

What are clinical signs of Toxocara canis?

• diarrhea

• vomiting

• weight loss in young puppies

• possible coughing during hepatotracheal migration

• intestinal obstruction

• “pot-bellied” puppies

Zoonotic

What is toxocara cati?

Roundworm of cats

Toxocara cati

• life cycle : ______

• Definitive host : ______

• Paratenic host(s): ________

• Transmission : ___________

• direct

• cat

• common

• ingestion of larvated eggs or paratenic host, transmammary

What are clinical signs of Toxocara cati?

• kittens usually asymptomatic

• may be listless, anorexic, “poo doer”, pot-belly

• adults may vomit worms

zoonotic

What is a key difference between Toxocara cati and Toxocara canis?

Toxocara canis is able to transmit transparently (in utero) while Toxocara cati can not

What is Toxasxaris leonina?

Roundworm of dogs and cats

Toxascaris leonina

• life cycle : ______

• Definitive host : ______

• Paratenic host(s): ________

• Transmission : ___________

• direct

• dog or cat

• possible

• ingestion of larvated eggs or paratenic host

What is a key distinction of Toxasxaris leonina?

No transmission in utero or from nursing and NO hepatotracheal migration

• its development remains confined to the small intestine

Toxocariasis infection in humans will cause what?

Larval migraine syndromes rather than intestinal roundworms infections

• never make it back to the large intestine

T. canis and T. cati in humans present clinical manifestations such as?

• visceral larval migrans (VLM)

• ocular larval migrans (OLM)

What are ascaris suum?

Swine ascarid or Large intestinal roundworm of pigs

Ascaris suum

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct

• pig

• ingestion of larvated eggs (L2)

What is a key distinction of Ascaris summ ?

“milk spots” in liver from migration

What are Parascaris spp. ?

Equine roundworm

Parascaris spp.

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct

• horse

• ingestion of larvated eggs (L2)-

What are clinical signs of Parascaris spp., especially with heavy worm burden?

intestinal obstruction and colic

• classically seen in foals

Parascaris spp. in foals

• infection occurs at ________

• mainly foals < _____

• _________ during hepatotracheal migration

• 1 month of age

• 6 months

• cough and nasal discharge

What are Toxocara vitulorum?

Roundworm of cattle

Toxocara vitulorum

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct

• cattle

• transmammary

What are the clinical signs of Toxocara vitulorum?

intestinal impaction and can cause death in calves

• calf can develop heavy warm burden from transmission from mother

What are Baylisascaris procyonis?

Raccoon Roundworm

Baylisascaris procyonis

• life cycle : ______

• Definitive host : ______

• Paratenic host(s): ________

• Transmission : ___________

• direct

• raccoon

• small mammals

• ingestion of eggs (L2)

Baylisascaris procyonis zoonotic? If so what can occur?

yes

• larva migrate aggressively and often invade the central nervous system

  • neural larval migrans

Pinworms are parasites of what kind of animals?

omnivores and herbivores

What are Oxyuris equi?

Pinworm of horses

Oxyuris equi

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct

• horse

• ingestion of eggs (L3)

Where do Oxyuris equi reside?

Adult worms in cecum, colon, rectum

What is a key distinguishing feature of Oxyuris equi?

The larval stage embed in the mucosa and cause mild erosions

What is a clinical sign of Oxyuris equi?

• Tail rubbing

  • irritation from eggs

• alopecia

• bear patches

• lesions on the rear

What is the best way to diagnose Oxyuris equi?

the cellophane tape method

• will not typically shed eggs on feces, so they can be missed on a fecal float

What are Enterobius vermicularis?

human pinworm

Enterobius vermicularis

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct

• human

• ingestion of larvated eggs

Enterobius vermicularis

• ____ a parasite of dogs and cats

NOT

What are Strongyloides spp. ?

intestinal threadworms

Strongyloides spp.

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct but can be facultative

• horse, dog, ruminant, pig

• L3 ingestion or skin penetration, transmammary

What is a distinguishing factor of Stronyloides spp.

They are free living OR female in small intestine

Strongyloides spp.

• ______ parasite

• females are ______

• infection : ______

• facultative

• parthenogenic

• autoinfection

What are Trichuris spp. ?

whipworms

Trichuris spp.

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct

• dog, ruminant, swine

• ingestion of embryonated egg

What are clinical signs of Trichuris spp. ?

They can cause diarrhea, bloody stool, straining to defecate, weight loss

What are some characteristics of Trichuris spp. ?

• eggs have bipolar plugs

  • are also heavier and as a result will take longer to come up in a fecal float

• Thin tail end and thick head; whip like appearance

What are Pearsonema spp. ?

Bladder worm

Pearsonema spp.

• life cycle : ______

• Definitive host : ______

• intermediate host(s): ________

• Transmission : ___________

• indirect

• dogs or cats

• earthworm

• ingestion of larvae in IH

Where are the eggs of Pearsonema spp. found?

In urine

What are Trichinella spiralis?

Trichina worm

Trichinella spiralis

• life cycle : ______

• Definitive host : ______

• Transmission : ___________

• direct ~ single host life cycle transmitted by carnivorism

• pig, human, other carnivores

• ingestion of encysted larvae in muscle

What is a distinguishing factor of Trichinella Spiralis?

Females lay larvae NOT eggs

• will move though the blood stream and into the skeletal muscle

Is Trichinella spiralis zoonotic?

Yes

• humans can get this from eating undercooked pork who is infected

• feral pigs are the main source of infection

What are Habronema & Draschia

Stomach and skin parasites of horses

Habronema & Draschia

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Transmission : ___________

• indirect

• horse

• muscidae flies

• ingestion of L3 (larvae) transmitted by the fly

What happens when Habronema & Drashia when they don’t make it to the stomach?

They will cause skin issues ( “summer sores” )

• where they are deposited will determine where they end up

What is parthenogenic ?

asexual reproduction, no males are needed

What are Thelazia spp. "?

eye worms

Thelazia spp.

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Transmission : ___________

• indirect

• dog/cat , horse, ruminant

• Musca autumnalis (face flies)

• L3 deposited by the fly during feeding

Where do adult Thelazia spp. want to end up?

In the conjunctival sacs

What are Spirocerca lupi?

Esophageal worm

Spirocerca lupi

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Paratenic host (s) : __________

• Transmission : ___________

• indirect

• dog, cat

• dung beetle

• rodent, chicken, small reptile, amphibian

• ingestion of L3 within the IH or PH

What is a distinguishing factor of Spirocerca lupi ?

worms live in esophageal nodules

• adults live in the esophagus

What are Physaloptera spp.

Stomach worm

Physaloptera spp.

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Paratenic host (s) : ___________

• Transmission : ___________

• indirect

• dog, cat

• beetle, cockroach

• rodent, small reptile, amphibian

• ingestion of L3 within IH or PH

What are clinical sighs of Physaloptera spp. ?

vomiting, diarrhea, dark stools

• suck blood from stomach mucosa

What are Dioctophyma renale ?

Giant kidney worm of dogs

Dioctophyma renale

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Transmission : ___________

• indirect

• dog

• earthworm

• ingestion of larvae in IH

What is a key distinguishing factor of Dioctophyma renale?

• Infects right kidney

• eggs are passed in urine

What are some key facts of Filarial worms?

• live in connective tissue ( including blood )

• indirect life cycle

• intermediate host : biting arthropod

• L3 transmitted during vector feeding

• no eggs

  • motile embryo called microfilaria

Filarial worm life cycle

Female produces ______ → in blood or tissue

_______ ________ ( intermediate host) acquires microfilaria during blood meal → develops into infective ______ larvae in the arthropod → transmitted to final host during blood meal → enters wound → develops during _______ to predilection site → mature into adult in _______ ________

• microfilaria

• biting arthropod

• L3

• migration

• pulmonary artery

What are Dirofilaria immitis

Canine Heartworm

Dirofilaria immitis

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Transmission : ___________

• indirect

• dog ( cat, ferret )

• mosquito

• L3 transmitted by infected female mosquito during feeding

How long does Dirofilaria immits infection take to allow for a positive antigen test

6 to 7 months post-infection

What are the limitations of Antigen test?

May be negative with :

• male only infections

• very low worm burdens

• immature infections

Where do adult Dirofilaria immitis reside ?

Right ventricle and pulmonary artery

Dirofilaria immitis

• clinical signs ________

form non to heart failure

How do Dirofilaria immitis affect cats?

• aberrant migration of worms ( eye, CNS )

• lung disease more common then in dogs

• acute pulmonary crisis

How do Dirofilaria immitis affect ferrets?

• respiratory symptoms similar to cats

• highly susceptible; low worm burdens can cause major issues

What are Onchocerca spp. ?

Horse threadworm

Onchocerca spp.

• life cycle : ______

• Definitive host : ______

• Intermediate host(s): ________

• Transmission : ___________

• indirect

• horse, ruminants

• culicoodides ( biting midges

• L3 transmitted by infected midge during feeding

Where do adult Onchocerca cervivalis reside?

Adult worms and larvae live under skin

• Adult migrate to nuchal ligament

• microfilariae cause cutaneous onchocerciasis (dermatitis)