Lecture 3: Nematodes (part 1) Flashcards by Jessica Buchy

canine ascarid (roundworm)

toxocara canis

eggs, thick shell with dark morula

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ascarid of cat

toxocara cati

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ascarid of both dogs and cats

toxascaris leonina (lighter, outer shell is smooth, not dark and rough like other ascarid eggs)

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what morphological feature can help ID ascarid adults

alae (cuticle) differs by spp

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ascarids discussed

t. canis
t. cati
toxascaris leonina
baylisascaris procyonis

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infective stage of T. canis

egg with L2 larvae

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possible routes of transmission to DH for T. canis

ingestion (direct trans)
transuterine
lactogenic
ingestion of paratenic host

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direct transmission (fecal) in dogs less than 3 mo old with toxocara canis

“tracheal migration”
ingests L2
larva hatches in SI, penetrates SI and goes to LN, liver, heart, pulmonary arteries, lungs
molts to L3 in alveoli and is coughed up/swallowed
matures in SI to L5

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direct transmission (fecal) in dogs older than 3 mo old with toxocara canis

“somatic migration”
ingests L2
hatches in SI, penetrates SI and enters cystemic circulation (doesn’t penetrate alveoli)
L2 larvae encyst in tissues
NO MATURATION occurs (IS of host stops development)

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how do puppies get infected with toxocara canis in utero

the hypobiotic L2 larvae mobilize around d42 pregnancy and migrate to fetuses

migrate to liver and molt to L3 and migrate to lungs at birth

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when can eggs be found in puppy feces infected transuterine by toxocara canis

23-40d old

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lactogenic transmission of toxocara canis

L2 larvae in mammary tissue passed to pupppies, NO MIGRATION

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Toxocara canis infection via paratenic host

ingest PH with encysted L2s (rodents). NO MIGRATION

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routes of infection that do not involve migration in the DH for toxocara canis

lactogenic, paratenic host ingestion

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toxocara cati direct transmission has __ migration vs the somatic migration seen with toxocara canis

tracheal migration

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most common route a cat is infected with toxocara cati

ingestion of paratenic host (rodent, cockroach, earthworm)

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is there migration with direct transmission of toxascaris leonina

no! migration with other spp via direct transmission

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pathologies caused by ascarides (roundworms)

more problems seen in young with heavy infections

death (rare) 
pneumonia 
intestinal obstruction V/D
pot belly 
Neurologic disorder

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diagnosing ascrids

fecal float, eggs float nicely and there will be a ton of them. can also see adults in feces

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treating ascarids

treat mother and litter!
fenbendazole dogs and bitches
selamectin for cats
remove feces daily, rodent and PH control

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is toxocara canis zoonotic

yes, causes visceral larval migrans

chronic granulomatous lesions in liver, lungs, brain, eye

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dirt eating childeren may get

toxocara canis, they are a paratenic host

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ascarid with DH being raccoons, kinkajous, and dogs

baylisascaris procyonis

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infective stage of baylisascaris procyonis

egg with L3

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paratenic host for baylisascaris procyonis

mice, rabbits, birds, humans

how can humans get baylisascaris procyonis

ingest larvated eggs in contaminated food/water/environment | consuming raw meat

CS in paratenic hosts of baylisascaris infections

visceral larval migrans causing neurologic disease severity of disease depends on number of larvae and spp rodents, rabbits, birds, primates have high susceptibility

CS in paratenic host for baylisascaris infections

low numbers = none | high numbers migrating = respiratory distress, granulomas, invasion of spinal cord, brain, death

infective stage of baylisascaris

L2 in egg

the esophageal worm

spirocerca lupi

DH for spirocerca lupi

caudal esophagus of dogs, cats, and wild canids and felids

IH for spirocerca lupi

dung beetle paratenic hosts: amphibians, repitles, birds

spirocerca lupi distribution

worldwide, mainly tropical/subtrop regions

adult spirocerca lupi roundworms

bright red and coiled

infective stage of spirocerca lupi

L3 in dung beetle

migration of spirocerca lupi in DH

L3 migrates from stomach to gastric arteries, aorta (stay here 2+mo) and finally to esophagus where they form nodules/mature/mate

CS from spirocerca lupi

``` roughened aorta spondylitis of thoracic vertebra migration to other aberrant sites esophageal obstruction granuloma around nodule can develop into sarcoma ```

granulomas formed around spirocerca lupi have been known to become

sarcomas

dx spirocerca lupi

fecal float with high spec grav endoscopy - most sensitive radiography (caudal esophageal mass, spondylitis)

tx spirocerca lupi

ivermectin tried first

the physaloptera stomach worm of cats

physaloptera praeputialis

the stomach worm of dogs

physaloptera rara

IH of physaloptera (stomach worm)

dung beetles, cockroach, grasshoppers

paratenic hosts of physaloptera

snake, rat, frog

eggs and adult physaloptera

small worms that curl up (males have alae on posterior end) | small, oval, thick shelled smooth egg

infective stage of physaloptera

L3 inside IH (beetle, roach, grass hopper)

CS physaloptera

usually asymptomatic | can cause edematous stomach with increased mucus and inflammation, melena, chronic vomiting and wt loss

dx physaloptera

fecal or vomit float using high spec grav may see adults in vomitus endoscopy

the cat puke worm or stomach worm of cats

ollulanus tricuspis

DH for ollulanus

stomach of cats, foxes, pigs, rarely dogs

lifecycle for ollulanus

direct

infective stage for ollulanus

female births L3 larvae = infective from birth

dx ollulanus tricuspis

worms in vomit baermann's test stomach irrication

threadworms

strongyloides stercoralis | strongyloides tumefaciens

parasitic stage of strongyloides (threadworm)

parthanogenic L3 females! not the free living males/females migrate lungs - trachea - esophagus - intestine

hookworms

``` ancylostoma a. caninum a. braziliense a. tubaeformae unicinaria stenocephala ```

Worm in dog that has 3 chitenized teeth on adult worm. Male has a copulatory bursa.

ancylostoma caninum

hookworm found in SI of cat, also has 3 pairs of teeth

ancylostoma tubaeformae

hookworm found in both dogs and cats but only has 2 pairs of teeth

ancylostoma braziliense

hookworm found in dogs in norther america that has a large buccal cavity and cutting plates

unicinaria stenocephala

Ancylostoma caninum life cycle

non-larvated eggs passed in feces, embyronate in environment within 1day L1 hatches L3 infective stage infects DH in many ways (oral, skin pen, transplacental, lactogenic, ingestion PH)

5 possible ways L3 infects DH

``` Ingestion L3 skin penetration transplacental lactogenic ingestion PH ```

most common route of infection for ancylostoma caninum

skin penetration!

describe the migration in a L3 a. caninum penetrating skin of a puppy

extensive migration | BV, heart, alveoli, bronchi

describe the migration in a L3 a. caninum penetrating skin of a older dog (over 3mo)

extensive migration but more of a "somatic route" | the L3 migrate and encyst in the muscle (hypobiotic, dormant)

how do you treat the encysted L3 ancylostoma caninum

no treatment for this stage, protected from drugs and host IS

how do cats get ancylostoma tubaeformae hookworms

ONLY acquired after birth via INGESTION (environmental contam)

most common CS a. caninum infection

anemia; puppies hit hardest due to low iron stores and lack of aquired immunity

which hookworm species are most pathogenic, they are voracious bloodsuckers

a. caninum, a. tubaeformae

young puppy with deteriorating health, pale mucous membranes, dark liquid feces but a negative fecal

suspect peracute hookworm disease from transmammary infection, enough adults can kill the puppy...treatment often doesn't work and they need blood transfusions will see CS before see eggs in feces

what is acute hookworm disease

sudden exposure of older pups to large numbers of larvae will have CS before eggs treatment is effective

what is chronic hookworm disease

no CS eggs in feces and reduced PCV, may be a "poor doer"

what is secondary hookworm disease

older dogs that are emaciated and anemic, usually hookworms are NOT the main culprit

treatment for a. caninum in dogs

adult worms: fenbend, moxidectin, pyrantel L4 larvae: moxidectin "break life cycle" this treatment is same for other spp hookworm

"sand worms" "plumber's itch" "creeping eruption"

L3 skin penatrations in humans (zoonotic) by | ancylostoma braziliense causing cutaneous larval migrans

whipworms

trichuris t. vulpis (dog) t. campanula (cat) t. serrata (cat)

where are whipworms located in DH

adults Mainly in cecum

infective stage for whipworms

embryonated eggs with L2