Lecture 4: Ascarids #3

Question 1

At what age is ideally when you can diagnose Parascaris equorum?

Answer 1

Expect to find in younger horses

a little past weaning: 6 to 9 months of age

Question 2

When diagnosing Parascaris equorum, where can you find adult Parascaris equorum?

Answer 2

Adult wroms in feces

necropsy: adults are found in small intestine

Question 3

Which species would you find this ascarid in?

Which egg is normal? Why?

Which is abnormal? Why?

Answer 3

Equine: Parascaris equorum

Left: normal egg

has all morphologic features that would be on a fresh sample

Right: abnormal

“bald egg” from old specimens

Question 4

True/False: Macrolide use in foals is AAEP’s reccomended treatment for Parascaris equorum.

Answer 4

False

There is a huge resistance to macrolides

Preferred treatment: Treat ascarids at 2-3 months and 6 months

Treat with benzimidazoles

Then treat for strongyles at 9 and 12 months

Question 5

A.) Why would you advise to not use pyrantel pamoate after diagnosing a severe Parascaris equorum infection in small intestine?

B.) What treatment would you then suggest?

*Treat with benzimidazole

Answer 5

A.) Use of pyrantel pamoate, piperazine, or ivermection paralyzes or kills rapidly when at high enough dosage.

After treatment of these medications there’s a huge mass of paralyzed/dead worms and there’s an increased chance of obstruction +/- rupture of small intestine.

B.) Use anthelmintic that kills parasites slowly or has lower efficacy against ascarids

*Treat with benzimidazole

Question 6

What’s the goal for prevention and control of P. equorum?

Answer 6

reduce number of infective eggs in environment

Question 7

What sanitation practices can you practice to prevent and control P. equorum?

Answer 7

Remove feces, bedding from stalls weekly

steam/pressure clean stall

Wash mare before foaling

Question 8

What’s the most important nematode parasite of swine?

Answer 8

Ascaris suum

Question 9

How is Ascaris suum transmitted?

Most common?

Answer 9

Fecal-Oral transmission is most common

Infection by ingestion of paratenic hosts

Question 10

True/False: Ascaris suum nematodes have cervical alae just like Parascaris equorum.

Answer 10

False!

Ascaris suum have similar alae to Parascaris equorum, but they’re similarity is that they have no alae (NOT that they both have cervical alae)

Question 11

What happens when an Ascaris suum egg is ingested by piglet?

Answer 11

Egg with infective larva ingested

larva undergoes liver-lung-tracheal migration

it’s coughed up and swallowed

matures to adults in small intestine

NO SOMATIC LARVAL MIGRATION

pre-patent period: ~8 weeks

Question 12

Which population in swine is the most prone to Ascaris suum?

Answer 12

Occurs mainly in young animals

COMMON THEME WITH ASCARIDS!

Naive pigs are vulnerable to A. suum at any age

Question 13

A.) You notice during your necropsy of a young piglet that the liver has “milk spots” on it, what caused this?

B.) Describe how these lesion occured.

Answer 13

A.) Ascaris suum larvae

B.) A. suum larval migration to liver

Intially there’s mechanical damage leading to focal hemorrhage

The animals has a hypersensitivity to the larvae which leads to inflammation which creates “milk spots” on liver

Eventually there can be hepatic interstitial fibrosis is inflammation occurs chronically

Question 14

What are some clinical signs and lesions for Ascaris suum?

Answer 14

Verminous pneumonia

larvae migrate from lung capillaries to alveoli

grossly: petechial hemorrhages in lungs

Hypersensitivity to larvae

dry cough, shallow, and rapid breathing

“Thumps” = audible expiratory effort

Pigs can appear stunted and pot-bellied

adult A. suum are in small intestine

Question 15

What would you suggest for treatment for a swine herd with A. suum?

Answer 15

Kill L4 larvae that mature to adult in small intestine

All of Big 3!

Ivermectin, doramectin, fenbendazole, levamisol, pyrantel tartrate, and piperazine

Kill migrating larvae

Pyrantel tartrate fed continuously kills newly hatched larvae and prevents milk spots in liver

Feed right before weaning

Prevent liver to lung migration

Thiabendazole prevents pnemonia, but not “milk spots”

Question 16

How would you control A. suum to limit prevalence in your herd of swine?

Answer 16

Great sanitation

treat pigs at weaning

maintain on feed with pyrantel tartrate

monitor herd/facility

necropsy: slaughter check

fecal exams

If you’re an organic pork producer.. good luck

Question 17

A.) Toxocara vitulorum is known to affect mainly which species?

B.) Which routes of infection do they exploit? (Any major way(s)?)

Answer 17

A.) Mainly in cattle

can infect sheep, goats, and other species

B.)

Ingestion of larvated egg (major)

Activated hypobiotic larvae in cow:

Transplacental infection

Lactogenic transmission (major)

Question 18

Which species fecal/oral larval migration is Toxocara vitulorum most like?

Answer 18

Toxocara canis

Young calves: liver-lung-trachea to SI

Older calves: liver-lung-somatic migration to hypobiotic in tissues

Question 19

What happens to T. vitulorum larvae when ingested in colostrum/milk?

Answer 19

develop directly to adults in small intestine

Question 20

A.) What are some clinical signs for Toxocara vitulorum?

B.) When do calves expell worms from SI?

Answer 20

A.) Very foul-smelling diarrhea

colic

Emaciation and death can occur

B.) Calves expel worms by 4-6 months of age

Question 21

You go to Dr. Google for consultation about treatment for Toxocara vitulorum, what would he/she suggest?

Answer 21

No specific treatment/medication is approved in US

Suggest piperazine, fenbendazole or levamisole

NO macrocyclic lactone

Question 22

You catch your neighbor’s kid chomping on some Raccon turds he found in a crevice in a tree. What parasitic nematode would you be worried that the kid has contracted from these flavorful treats?

Answer 22

Baylisascaris procyonis

Raccoon roundworm

Question 23

A.) Baylisascaris procyonis has _____alae.

B.) Which species have similar alae pattern?

Answer 23

A.) no

B.) P. equorum

T. suum

Question 24

Which pathway(s) does a raccoon acquire Baylisascaris procyonis?

Answer 24

Ingestion of paratenic host is the most common way a raccoon acquires B. procyonis

Question 25

A.)Once a mouse infected with Baylisascaris procyonis is eaten by a raccoon, what happens to paratenic lavae in the raccoon? B.) You miraculously recorded the killing of mouse and saw the mouse exhibiting weird movement and altered behavior? How has B. procyonis caused this in the mouse?

Answer 25

A.) B. procyonis is nonpathogenic in raccoons B.) Paratenic host larvae undergo liver-lung-somatic migration 5-10% of migrating larvae randomly enter CNS 1-3 larvae in CNS can be fatal alters behavior of paratenic host

Question 26

A.) How would you treat B. procyonis in a raccoon? B.)What preventative measures can you take to limit B. procyonis exposure to clients and yourself?

Answer 26

A.) Use wormers effective against dog and cat ascarids B.) Treat ***_CAPTIVE_*** *raccoons* * wash hands after handling raccoons* * keep wild raccoons out of barns and sheds* * pick up and destroy raccoon feces*

Question 27

Which egg belongs to which species of Ascarid?

Answer 27

a) T. canis b. ) B. procyonis c. ) T. leonina

Question 28

Your dog just ate some raccoon feces. You do a fecal float on the dog's feces. How do you tell a T. canis egg froma B. procyonis egg?

Answer 28

B. procyonis egg is smaller than T. canis The shell wall of B. procyonis is finely granular and may be brown

Question 29

Here are the results of the fecal sample of your dog that ate some raccoon feces. There are 3 different parasites present, what are they?

Answer 29

A.) Toxocara canis B.) Ancylostoma sp. (hookworm) C.) Baylisascaris procyonis

Question 30

What are some clincal signs that could occur due to larval migration of Baylisascaris?

Answer 30

Possible respiratory signs CNS signs: can mimic rabies

Question 31

# Define: a) visceral toxocariasis b) ocular toxicariasis c) covert toxocariais

Answer 31

a) prolonged somatic migration of larval parasites in an abnormal host b) larvae migrates to eyes c) non-specific migration of larvae similar to visceral larval migration but less severe

Question 32

1. What most commonly causes visceral larval migrans? 2. What's the most feared after ingestion of eggs?

Answer 32

1. T. canis 1. T. cati can cause as well 2. Baylisascaris procyonis 1. death is likely after ingestion

Question 33

What are some risk factors for human VLM?

Answer 33

Dog and cat ascarids are prolific egg layers (esp dogs/cats with inadequate vet care) sandboxes/playgrounds are nesting ground for dog/cat feces most common in children \<6 years old

Question 34

How would you describe a T. canis larval infection of human eye? Do they produce a bilateral or unilateral eye lesion(s)?

Answer 34

Ocular larval migrans Cause unilateral inner eye lesion similar to retinoblastoma

Question 35

True/False: Ascaris suum can infect sheep and cattle.

Answer 35

True clinical signs cuased by larval migration