Difference between revisions of "Ascaridoidea"

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**egg hatches in intestine → larva penetrates intestinal mucosa → hepatic portal blood → liver → venous blood → heart → lung capillaries → alveoli → ascends trachea → swallowed → small intestine (where the adults develop)
 
**egg hatches in intestine → larva penetrates intestinal mucosa → hepatic portal blood → liver → venous blood → heart → lung capillaries → alveoli → ascends trachea → swallowed → small intestine (where the adults develop)
  
  NOTE: there are important variations on this theme; for example, the migratory larvae of some species can cross the placenta or enter the mammary glands (examples of vertical transmission); while some species will utilise paratenic or intermediate hosts.
+
  NOTE: there are important variations on this theme; for example, the migratory larvae of some species can cross the placenta or enter the mammary glands (examples of vertical transmission); while some species will utilise paratenic or intermediate hosts.
  
  

Revision as of 12:41, 9 January 2009



Infectious agents and parasitesWikiBugs Banner.png
PARASITES
NEMATODES



General Appearance

Toxocara cati - Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine
Toxoscaris leonina - Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine
Toxocara canis - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Toxoscaris leonina - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
  • Non-bursate
  • Big fleshy worms; typically 5-40cm long (depending on age, sex and species)
  • Three lips around the mouth
  • A single-bulbed pharynx

General Life-Cycle

  • Adult females in small intestine lay eggs
  • Eggs have a thick protective shell
  • Some also have a sticky outer albuminoid coat
  • Eggs passed in faeces
  • L1 → infective L2 inside the egg
  • Infection is by ingestion of the embryonated egg (egg in which a larva has formed)
  • Eggs can remain viable in humid environment for up to 5 years
  • After hatching in the intestine, the larvae of most species (but not all) undergo hepato-tracheal migration:
    • egg hatches in intestine → larva penetrates intestinal mucosa → hepatic portal blood → liver → venous blood → heart → lung capillaries → alveoli → ascends trachea → swallowed → small intestine (where the adults develop)
NOTE: there are important variations on this theme; for example, the migratory larvae of some species can cross the placenta or enter the mammary glands (examples of vertical transmission); while some species will utilise paratenic or intermediate hosts.




Ascaridida

Occlusion of pancreatic ducts sometimes happens Pancreas - parasitic

In Peritoneal Cavity Parasitic - Pathology