Nematodes- Order Ascaridida, Superfamily Ascaridoidea

Question 1

Order Ascaridida- General

Answer 1

• Ascaridoidea and Heterakoidea
• non-bursate nematodes
• large white worms
• direct life cycle
• infection by L2 or L3 IN EGG

Question 2

Superfamily Ascaridoidea

Answer 2

roundworm or ascarid
Life cycle: direct, infective L2 or L3 in egg, fresh egg is not infective, takes ~2 weeks for egg to become infected, poop usually gone by then
ID: large white nematodes with 3 lips, size depends on host
Location: adults in small intestine
Egg: thick walled (resistant), round, brown, rough
Transmission: per os (all spp.), paratenic, TM and/or TP (imp) in some species
Larval migration: hepatic-tracheal
Fecund females–> produce large amounts of eggs, 10-15 thou
Infect young animals–> strong immunity in adults
Somatic stages in adult animals –> immune system prevents migration so larvae arrest somewhere in tissue
CS: obstruction, pot belly, adults in vomit, pneumonia with heavy infections, migration CS BEFORE eggs in feces
Dx: fecal float, egg is Dx stage
no anemia

Question 3

Toxocara canis

Answer 3

Host: dogs
PPP: 3-5 weeks
ID:
adults: 10-12cm
egg: dark brown, round, thick pitted shell, avg size, proteinaceous layer, morula taking up whole egg
Transmission: per os, TP, TM, PH–> puppies can be born with it, can see CS at 7 days old, egg to egg w/ L2/L3: 2-4 weeks
Heavy infections in puppies: vomit after each meal bc small intestine is filled with worms–> nutrition decreases. entire worms pass with feces or vomit, feces are unformed
TP/TM infections can die from pneumonia; hepatic tracheal migration
CS: before eggs (before 3 wks), intestinal obstruction, potbelly, pneumonia
Path: depends on age of dog (immunity w/age, puppies=small), and #, site, & age of worms
adult dogs can have arrested larvae in tissue waiting for immune system to go down–> female dog can have enough arrested larvae to infect 2-3 litters
adults have more room in SI and lungs for migration, no issues
Zoonotic: visceral and ocular larval migrans–> musy inform the public, can be sued
Dx: eggs in fecal float (won’t see eggs until >3 wks)
-Adults: necropsy, feces, vomit, mostly based on CS
Tx: MANAGE ENVIRONMENT (CRITICAL)–> pick up poop! eggs will last years…tx mom when pregnant AND at the same time as puppies (her immunity is down)
Tx puppies at 2,4,6,8 weeks
*Tx to kill L4 and immature adults pre-egg shedding at ~ 2 weeks before they output eggs

Question 4

Toxocara cati

Answer 4

Host: cats, PH: rats, birds, etc
PPP: 4-8 wks
ID: Adults: 8-10cm, Egg: same as T.canis
Transmission: per os, TM, PH
Compared to T. canis: don;t migrate as intensively--> not as heavy pneumonia as puppies
less immunity--> in adults more
no TP--> slightly older kittens
zoonoses rare

Question 5

Toxascaris leonina

Answer 5

Hosts: cats, dogs, foxes, have PH
PPP: 11 wks, longer, see post weaning
ID: Adults: 6-12cm
Egg: oval w smooth thick shell, no proteinaceous layer, have gelatinous layer instead…morula isnt as dark and doesn’t fill all the space (diff from Toxocara spp.)
-no migration: lazy worm–> no pneumonia/lung issues
-less immunity & less pathogenic
-egg to egg w L2/L3 less time than T.canis
NOT ZOONOTIC
Leona Lewis can’t have lung issues

Question 6

Baylisascaris procyonis

Answer 6

Host: FH: raccoons, accidental host: dogs (can develop into adults, parasite doesn’t behave aberrantly), have PH
-Zoonotic w high lvls of VLM–> most concerned about humans, can cause permanent retinal damage
ID: send to specialist for egg differentiation
“Lisa’s bae accidentally touched a raccoon”

Question 7

Parascaris equorum

Answer 7

Host: equine
PPP: 10-12 weeks (coprophagia if eggs in foal under 10 weeks) –> worm is 3x the size, so takes 3x as long to grow to that size (as T. canis)
ID: Adults: 30cm (1 ft), Eggs: slightly larger than toxocara
Path: hepatic tracheal migration –> young foals can get bronchitis
-egg to egg w/ L2/L3 <2 weeks (slightly less than T.canis)
CS: mod/heavy infections: unthriftiness in foals, production losses, coughing, obstruction and perforation (large concern)
Dx: McMaster
Tx: anthelmintic resistance
Tx timing! tx at 2 mo (want to tx BEFORE end of PPP)… if you wait to tx until end of PPP, worms will clump, foal will colic, perforate and die
Tx slowly, killing worms all at once can cause obstruction

Question 8

Parascaris univalens

Answer 8

• mistakenly IDed for Parascaris equorum
• increasing in prevalence
• can infect ADULT HORSES

Question 9

Toxocara vitulorum

Answer 9

• cattle and buffalo

- transmammary infection

Question 10

Ascaris suum

Answer 10

Hosts: FH: pigs, PH earthworm, dungbeetle
-zoonotic
PPP: 6-8 wks
Eggs: last up to 10 yrs, impossible to get rid of/control
ID: adults: 40 cm LORGE, Eggs: round, thick shelled, mammilated
-egg to egg w L2: 1-3 mo (longer)
Path: hepatic tracheal migration, heavy infections=transient pneumonia (piglets under 4 mo)
CS: MILK SPOTS, condemn liver, intestinal disturbances, poor feed conversion, slow weight gain–> due to larvae migrating thru liver to lungs
Dx: McMaster, outdoor/indoor production, most persistent and resistant even in modern facilities
Tx: treat/wash sows pre-farrowing (eggs stick to mom, babies consume), tx piglets at weaning, use feed-thru anthelmintics