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Parasitology > Day 3: Ascarid > Flashcards

Day 3: Ascarid Flashcards

1
Q

What is the morphology and generalized life cycle of ascarids

A

Big worms in all animal species
Direct lifecycle with no intermediate host

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2
Q

Which ascarid is found in dogs

A

Toxocara canis
Toxascaris leonina

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3
Q

Which ascarid is found in cats

A

Toxascaris leonina
Toxocara cati

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4
Q

What is the morphology of Toxocara canis

A

Very large stout-bodied worms (6-10 inches long)

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5
Q

What is the lifecycle of Toxocara canis

A

Dogs infected when they ingest an egg containing L2 larva or migrating larva across the placenta
L2 hatches out of the egg and penetrates the intestinal wall
L2 larvae carried to the liver and migrate
L2 larva carried to lungs via circulation and molt to L3
L3 larva coughed up and swallowed
L3 larva molt to L4 and adults live in small intestines

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6
Q

How long is the prepatent period for Toxocara canis

A

4 weeks unless acquired in utero then it is 3 weeks

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7
Q

When does Toxocara canis perform tracheal migration

A

Occurs in puppies <3 months of age or in older dogs

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8
Q

When does toxocara canis perform somatic migration

A

Dogs >3 months
Larvae are carried to the lungs by circulation then to the muscles, liver and kidney where they arrest
Male dogs are a dead end source
Female dogs, larvae are mobilized during second month of pregnancy into the vasculature and cross the placenta and infect pups in utero
Pups pass eggs in feces shortly after birth (by 3 weeks) due to transplacental transmission
Parenteral larval stores in bitches will infect litters for at least 2 gestations

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9
Q

What are the routes of infection for Toxocara canis

A

Transplacental (most common)
Transmammary
Ingestion of embryonated egg from ground or in feces when bitch licks pups
Ingestion of paratenic host that has eggs within it (mouse)

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10
Q

What are the clinical signs of toxocara canis in young puppies with heavy infections acquired in-utero

A

Pneumonia
Inflammation of the stomach and intestines
Marked distension of the abdomen
Severe diarrhea
Vomiting
Dehydration
Death can occur in 12-72 hours

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11
Q

What do clinical signs depend on for Toxocara canis

A

Age of dog
Number of worms
Location of worms
Stage of worms

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12
Q

What are the clinical signs of toxocara canis in puppies that are 6 weeks to 6 months after early infection

A

Pot bellied appearance
Thin even when eating
Intermittent diarrhea
Occasionally anemic
Worms may be found in vomitus

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13
Q

What happens to older dogs and cats that become infected with toxocara canis

A

Thin with a poor haircoat due to resistance

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14
Q

What is the morphology of toxascaris leonina

A

Smaller than toxocara canis
Found in the dog and cat

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15
Q

What is the lifecycle of toxascaris leonina

A

Prepatent period is 6 weeks
Simple lifecycle
All development occurs in GI tract

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16
Q

What are the routes of infection of toxascaris leonina in dogs

A

Ingestion of egg with infection larvae

17
Q

What are the routes of infection of toxascaris leonina in cats

A

ingestion of paratenic hosts (mouse) that ingested an egg

18
Q

What are the clinical signs of Toxascaris leonina

A

Not serious unless many worms
Diarrhea
Poor body condition
Dehydration

19
Q

What is the morphology of toxocara cati

A

Smaller than toxocara canis
Found in cat
Rare in dogs

20
Q

What the route of infection of toxocara cati

A

ingestion of paratenic host
Transmammary transmission (Rare)
migration outside of GI tract (Rare)

21
Q

What are the clinical signs of toxocara cati

A

Usually mild
Thin
Often vomit immature or adult worms

22
Q

What is the morphology of Parascaris equorum

A

Horse roundworm
Very large stout adult worms (6-8 inches long)

23
Q

What are the clinical signs of Parascaris equorum

A

Affects foals <6 months of age
Migrating larvae can cause “summer colds” with coughing
Fever
Anorexia
Diarrhea
Respiratory signs
Nasal discharge
Congestion

24
Q

What is the clinical pathology of parascaris equorum

A

Masses of these large worms can cause bile duct and intestinal obstruction or perforation
Intussusceptions can occur
Blockage can lead to debilitation
Poor growth
Death

25
Q

What is the morphology of Ascaris suum

A

Large sized roundworms in swine
These are the most common and largest swine worm

26
Q

What is the epidemiology of Ascaris suum

A

Most important parasites of swine
Extreme environmental resistance of eggs allows them to persist for years
Young pigs 2-5 months of age have the most severe clinical signs

27
Q

What are some clinical signs of Ascaris suum

A

Weight loss
Failure to grow
Serious diarrhea
Bacterial pneumonia-larvae bring back bacteria to lungs from intestines

28
Q

What is the pathology of Ascaris suum

A

Liver damage (milk spots)-migrating larvae
Economic losses
Blockage of intestines and bile duct in heavy infections
Cause intussusception and death

29
Q

What do Ascarid look like in fecal flotation

A

Thick-shelled mammillated eggs that are unembryonated when shed in feces
Egg is inactive only after 1-2 weeks embryonation

29
Q

how do you diagnose Asscarids

A

Fecal flotation

30
Q

What is the zoonosis of Ascarids

A

Any of the Ascarid species can cause Visceral Larval migrans (VLM) if ingested by a human
Larvae can migrate to the eye or the brain

31
Q

How to control Ascarids

A

Eggs of all species are extremely tough and survive cold and hot temperatures
Eggs of all species develop most rapidly at warm temperatures
Most ascarid eggs are infective by 1-2 weeks
Try to prevent environmental contamination
Removal of these eggs from kennels is extremely difficult

32
Q

How do Ascarid species affect animals

A

Most anthelminthics are effective for GI stages, but not tissue stages
Fenbendazole and ivermectin are effective against tissue stages

33
Q

How to treat dogs with Ascarids

A

Bitch should be treated at breeding and during lactation
Treat puppies every 2-3 weeks starting 2 weeks after birth until 3 months of age
Effective drugs include Ivermectin, milbemycin oxime, pyrantel pamoate, piperazine

34
Q

How to treat horses with Ascarids

A

Treated with ivermectin or fenbendazole
Must decontaminate environment or move to clean environment

34
Q

How to treat cats with Ascarids

A

Pregnant queens should be dewormed late in pregnancy to protect kittens
Kittens should be dewormed beginning at 4-8 weeks of age and then every 6-8 weeks until they reach 1 year

Parasitology (10 decks)

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