Nematoda - ascaridida

Question 1

What are some features of Order Ascaridida?

Answer 1

• white opague bodied
• three lips
• very prolific
• thick mammilated shelled with one cell inside. most disinfections have no effect on the egg
• small intestine
• mammals, birds and fish
• zoonotic importance

Question 2

Where is Ascaris suum found?

Answer 2

• small intestine worm in pigs. infection is caused by ingestion of infected eggs.
• high prevalence in pigs younger than six months
• small intestines and sometimes stomach and bile ducts.
• larvae cause milk spots in liver and lungs whereas adults cause lesions in the digestive system.
• stouts bodied adults and they are pinkish yellowish

Question 3

What is VLM?

Answer 3

Visceral Larva Migration which describes the movement and invasion of larvae through host tissues of paratenic hosts.

Question 4

What is the life cycle of the Ascaris suum parasite?

Answer 4

liver within 24h –> blood to heart and lungs –> break out of alveolar capillary –> alveoli –> bronchi –> trachea –> pharynx –> swallowed –> intestines where they mature.
ppt = 60 days

Question 5

What’s prepatent time? (PPT)

Answer 5

the time required to reach adulthood

Question 6

What are Paracaris equorum?

Answer 6

these are parasites in the small intestine of the horse.

Question 7

What are some Paracaris equorum features?

Answer 7

• large anterior end with 3 conspicous lips
• subglobular, thick shell, two cells inside.
• ppt= 80 days

Question 8

What is toxocara vitulorum?

Answer 8

parasites in small intestine of the calves.

- three well defined lips and eggs are thick shelled and finely pitted with one cell inside.

Question 9

What is a patent infection?

Answer 9

animals that are infected with adult parasites.

Question 10

What is the life cycle of the Toxocara vitulorum?

Answer 10

they do not reach the patent phase within the cows instead they reach hypobiosis in the liver, lungs, muscles or brain then during parturition they migrate to mammary glands to infect calves.

Question 11

What are the ascarids of dogs and cats?

Answer 11

Toxocara canis, cati and leonina.

Question 12

What are some features of Toxocara canis?

Answer 12

• most frequent parasite in dogs
• three well defined lips
• cervical alae
• small intestine
• zoonotic potential
• causes VLM and OLM (ocular larvae migration) in humans
• sub spherical thick shelled with finely pitted coat

Question 13

How do Toxocara canis infect the host?

Answer 13

• tracheal migration
  lover –> heart –> lungs –> trachea –> pharynx
• somatic migration (through tissues)
  larvae from lungs –> heart –> muscles –> kidney –> brain and enter hypobosis.

Question 14

What factors affect toxocara canis migration?

Answer 14

• age
• immunity
• sex

Question 15

When do toxocara canis reactivate from hypobiosis?

Answer 15

- 42 days of gestation due to hormonal changes 
they migrate to: 
- transplacental 
- transmammary infection
- intestines

Question 16

What’s different within male hosts for toxocara canis?

Answer 16

in healthy males the immune system is most likely going to destroy the larvae. in immuno-suppressed animals they are reactivated and migrate to intestines where they mature.

Question 17

What are the modes of infection in a natural host of toxocara canis?

Answer 17

in puppies - transplacental or galatogen (parasites mature in the intestine there is no migration).
older puppies or adults - embryonated eggs, paratenic host and immature parasites.

Question 18

What is toxocara cati eggs morphology?

Answer 18

• smaller than T.canis
• brown
• thick, pitted and one cell inside the egg.

Question 19

What is T.cati life cycle?

Answer 19

eggs are shed into the environment where they develop they can then undergo:
tracheal migration (from liver to small intestine) 
somatic migration (larvae might go into muscles). 

it is not infective through the placenta, just through milk (mammary glands).

Question 20

What are the Ascarid species of birds?

Answer 20

ascaridia galli - small intestine
heterakis gallinarum - caeca
heterakis isolonche - caeca of phesants