Difference between revisions of "Ascaridoidea"
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[[Image:Toxocara canis.jpg|thumb|right|150px|''Toxocara canis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]] | [[Image:Toxocara canis.jpg|thumb|right|150px|''Toxocara canis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]] | ||
[[Image:Toxoscaris leonina 2.jpg|thumb|right|150px|''Toxoscaris leonina'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]] | [[Image:Toxoscaris leonina 2.jpg|thumb|right|150px|''Toxoscaris leonina'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]] | ||
| − | *Non-bursate | + | *Non-bursate |
| − | *Big fleshy worms; typically 5-40cm long (depending on age, sex and species) | + | *Big fleshy worms; typically 5-40cm long (depending on age, sex and species) |
| − | *Three lips around the mouth | + | *Three lips around the mouth |
| − | *A single-bulbed pharynx | + | *A single-bulbed pharynx |
| − | |||
== General Life-Cycle == | == General Life-Cycle == | ||
| − | *Adult females in small intestine lay eggs | + | *Adult females in small intestine lay eggs |
| − | *Eggs have a thick protective shell | + | *Eggs have a thick protective shell |
| − | *Some also have a sticky outer albuminoid coat | + | *Some also have a sticky outer albuminoid coat |
| − | *Eggs passed in faeces | + | *Eggs passed in faeces |
| − | *L1 → infective L2 inside the egg | + | *L1 → infective L2 inside the egg |
| − | *Infection is by ingestion of the embryonated egg (egg in which a larva has formed) | + | *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 | + | *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: | *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) | + | **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 12:38, 9 January 2009
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This article is still under construction. |
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General Appearance
- 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.
Occlusion of pancreatic ducts sometimes happens Pancreas - parasitic
In Peritoneal Cavity Parasitic - Pathology
- Parascaris equorum in rhinitis and lungs
- Ascarid larvae in myositis