Difference between revisions of "Ancylostomatoidea Life-Cycle"

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(Created page with '*Like that of the Strongyloidea, but infection can be by ingestion and/or skin penetration *''Ancylostoma'' in myositis *''Ancylos…')
 
 
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*Like that of the Strongyloidea, but infection can be by ingestion and/or skin penetration
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==Description==
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The life-cycle of the [[:Category:Ancylostomatoidea|Ancylostomatoidea]] is similar to that of the [[Strongyloidea]], involving a single (definitive) host and several environmental stages.  Eggs are produced by adult hookworms in the small intestine of the definitive host (the dog or cat) and passed out in faeces, where they develop to the L3 larval stage within 2-10 days.  The larvae are active in moist environments but are quickly killed by desiccation.  Dogs and cats are exposed to L3 larvae present on contaminated food or environmental surfaces and the larvae may be ingested or they may penetrate the skin, the major difference between their life-cycle and that of the Strongyloidea. 
  
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*''Ancylostoma'' in [[Muscles Inflammatory - Pathology#Nematodes|myositis]]
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===Transcutaneous Entry===
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*''Ancylostoma'' and ''Uncinaria'' in [[Parasitic skin infections - Pathology#Hookworms|skin infections]]
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Larvae that enter the body transcutaneously migrate into the blood, travel to the '''lungs and trachea''' and move into the airways.  The larvae are then coughed up and swallowed to complete the final stage of their development (to adults) in the small intestine.  The adult hookworms use their large buccal cavities to embed their heads deep into the mucosal layer of the small intestine.  Local cutaneous immunity develops quickly to hookworm larvae and, when the host reaches adulthood, the larvae are usually killed in the skin before they can reach the blood.
  
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The hookworms are 1-2cm long bursate nematodes. They are easily identified under the microscope, as they have a large buccal cavity with teeth, and the mouth points dorsally. Some have teeth around the rim of the mouth which can be used for identification, and which are used to embed the head deeply into the mucosa of the small intestine. The life-cycle is typical for the superfamily.
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===Oral Entry===
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Most ingested L3 larvae develop through the remaining stages (L4, L5 and adult) '''directly in the small intestine''' but, in the case of ''[[Ancylostoma caninum]]'', a small proportion will migrate to distant tissues (mainly '''skeletal muscle''' and '''fat''') via the blood and remain encysted as dormant larvae.  When female dogs lactate, these somatic larvae reactivate and migrate to '''mammary glands''' where they may be transmitted to neonates for up to three weeks after parturition. It is also possible for somatic larvae to reactivate in heavily debilitated animals and return to the intestine.
  
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As with all hookworms, the L3 can penetrate the skin. A protective immunity develops, and so enteric disease is largely confined to pups. Some dogs develop a hypersensitivity, leading to a pedal dermatitis which can affect all ages.
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===Clinical Disease===
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[[Category:Ancylostomatoidea]]
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For clinical disease caused by hookworms, see:
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*[[Hookworm Dermatosis]]
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For more information about specific species, see:
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*''[[Ancylostoma caninum]]''   
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*''[[Uncinaria stenocephala]]''
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For zoonotic disease caused by hookworms, see:
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*[[Cutaneous Larva Migrans]]
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{{Learning
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|literature search = [http://www.cabdirect.org/search.html?q=title%3A%28%22Ancylostoma+caninum%22%29+AND+ab%3A%28%22Life+Cycle%22%29 ''Ancylostoma caninum'' life cycle publications]
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}}
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{{review}}
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{{OpenPages}}
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[[Category:Ancylostomatoidea|B]]
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[[Category:Expert_Review]]

Latest revision as of 15:59, 5 July 2012


Description

The life-cycle of the Ancylostomatoidea is similar to that of the Strongyloidea, involving a single (definitive) host and several environmental stages. Eggs are produced by adult hookworms in the small intestine of the definitive host (the dog or cat) and passed out in faeces, where they develop to the L3 larval stage within 2-10 days. The larvae are active in moist environments but are quickly killed by desiccation. Dogs and cats are exposed to L3 larvae present on contaminated food or environmental surfaces and the larvae may be ingested or they may penetrate the skin, the major difference between their life-cycle and that of the Strongyloidea.

Transcutaneous Entry

Larvae that enter the body transcutaneously migrate into the blood, travel to the lungs and trachea and move into the airways. The larvae are then coughed up and swallowed to complete the final stage of their development (to adults) in the small intestine. The adult hookworms use their large buccal cavities to embed their heads deep into the mucosal layer of the small intestine. Local cutaneous immunity develops quickly to hookworm larvae and, when the host reaches adulthood, the larvae are usually killed in the skin before they can reach the blood.

Oral Entry

Most ingested L3 larvae develop through the remaining stages (L4, L5 and adult) directly in the small intestine but, in the case of Ancylostoma caninum, a small proportion will migrate to distant tissues (mainly skeletal muscle and fat) via the blood and remain encysted as dormant larvae. When female dogs lactate, these somatic larvae reactivate and migrate to mammary glands where they may be transmitted to neonates for up to three weeks after parturition. It is also possible for somatic larvae to reactivate in heavily debilitated animals and return to the intestine.

Clinical Disease

For clinical disease caused by hookworms, see:

For more information about specific species, see:

For zoonotic disease caused by hookworms, see:


Ancylostomatoidea Life-Cycle Learning Resources
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Literature Search
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(CABI log in required) 		Ancylostoma caninum life cycle publications


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