Ascarids Flashcards
What are the physical characteristics of the typical Ascarid?
- Anterior end
- 3 lips
- Long, narrow alae
- Posterior end
- NO bursa in the male
- Which parasite is this, genus and species?
- What is “A”?
- Toxocara canis
- Cervical alae
What are the characteristics of an Ascarid egg?
- Round to elliptical
- Thick shell
- Brown/black
- Pitted
- Contents nearly fill the interior
Explain a little bit about the infective stage of an Ascarid:
- Is there a direct or indirect life cycle?
- Is there an egg or fee-living L3?
- How can infection be acquired?
- Direct life cycle
- Egg (NO free-living L3)
- Transplacentally, transmammary, ingection, paratenic host
If there is no free-living L3, where can the L3 be found?
Within the ascarid egg
With Toxocara canis in particular, which modes of infection allow for somatic migration?
- Fecal - oral transmission
- Paratenic host
As for Ascarids like Toxocara canis, there is no free-living L3s - so where does the larvated egg hatch and release the L3s?
Duodenum
From ingestion of a Toxocara canis egg:
- How long until L3 is in the duodenum?
- How long until L3 is in the liver?
- How long until L3 is in the lung?
- 4 hours
- 24 hours from duodenum
- 12 - 24 hours from the liver
- 4 days TOTAL
How does larval migration for Toxocara canis differ between the young and adults?
- Young (< 12 weeks old)
- Liver - lung - tracheal migration
- Adults (> 12 weeks old)
- Liver - lung - somatic migration
What is the pre-patent period of Toxocara canis within the Liver-lung-tracheal migration?
30 - 35 days
How long does it take Toxocara canis to get from the small intestine upon initial infection back to the small intestine after migration?
(Liver - lung - tracheal migration)
10 - 15 days
Toxocara canis that act through somatic migration - which tissues might they affect?
- Muscle
- Kidneys
- Liver
- Brain
How long does it take Toxocara canis to get from the small intestine upon intial infection to the somatic tissue after migration?
4 - 30 days
How long is the pre-patent period for Toxocara canis in a pup that acquired the infection transplacentally?
25 - 30 days
- What is the most common mode of transmission for Toxocara canis?
- What is the pre-patent period for this form of transmission?
- Transplacental transmission
- 25 - 30 days