Difference between revisions of "Strongyloides"

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{{Taxobox
 
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|name =''Strongyloides spp.''
 
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|kingdom =Animalia
 
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|sub-kingdom =
 
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|phylum =[[:Category:Nematodes|Nematoda]]
 
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|super-class =
 
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|class = Chromadorea
 
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|sub-class =
 
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|super-order =
 
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|order = Rhabditida
 
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|sub-order = Rhabditina
 
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|super-family =Rhabditoidea
 
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|family =Strongyloididae
 
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|sub-family =
 
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|genus =Strongloides
 
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|species =''S. westeri''
 
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}}
 
 
[[Image:Strongyloides stercoralis 2.jpg|thumb|right|150px|''Strongyloides stercoralis'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
 
[[Image:Strongyloides stercoralis 2.jpg|thumb|right|150px|''Strongyloides stercoralis'' - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
 
[[Image:Strongyloides stercoralis.jpg|thumb|right|150px|''Strongyloides stercoralis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Strongyloides stercoralis.jpg|thumb|right|150px|''Strongyloides stercoralis'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Strongyloides larvae.jpg|thumb|right|150px|''Strongyloides'' larvae - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Strongyloides larvae.jpg|thumb|right|150px|''Strongyloides'' larvae - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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[[Image:Strongyloides.jpg|thumb|right|150px|''Strongyloides'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
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[[Image:Strongyloides.jpg|thumb|right|150px|''Strongyloides'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]][[Category:Rhabditoidea]]
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==Overview==
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This is the only genus of veterinary importance in the super-family Rhabditoidea. There are a number of species that are of particular importance and these are mainly host specific.
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=== ''STRONGYLOIDES WESTERI'' ===
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==== General ====
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*Rhabditoid, small intestine.
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*Commonest in foals <6months old.
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*FIRST PARASITE TO WHICH FOALS ARE EXPOSED.
  
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=== ''Strongyloides westeri'' ===
 
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This is a parasite of the horse and is most commonly seen in young foals, less than six months in age. This is usually the fisrt parasite to which foals are exposed and therfore they have very little immunity to these infections. The predeliction site for these worms is the small intestine.
 
 
==== Morphology ====
 
==== Morphology ====
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The distinguishing features of this worm are:
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*<6mm long, similar to small trichostrongyles.
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*Very small, 6-9mm long
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*Only female worms parasitic.
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*Slender, hair-like
 
 
*Long oesophagus (up to one third of body length).
 
*Long oesophagus (up to one third of body length).
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*Intestines and ovaries intertwined in caudal body
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*Blunt ended tail
 
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The eggs are small and oval with a thin shell, they will often hatch in the large intestine so L1 larvae are expelled in the hosts faeces.
 
 
==== Life-Cycle ====
 
==== Life-Cycle ====
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''S. westeri'' has a typical [[:Category:Rhabditoidea|strongyloides]] life cycle, with both a free living and parasitic cycle. The free living cycle involves male and female worms reproducing sexually on the ground, this can occur for several generation with no parasitism taking place. The parasitic phase involves only female worms and occurs from ingesion of L3 larvae or their penetration through the hosts skin. Infection my also be transmissed vertically from the dam to the foal by larval migration to the mammary tissue and ingestion by the foal with the dams milk. Once in the host the larvae migrate to the small intestine where they tunnel into the epithelium at the base of the villi and moult to L4 and then adult females. Females produce eggs without sexual interaction that can develop to become both male and female larvae. The pre patent period is between 1 and 2 weeks dependant on the level of infection.
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*Parasitic and free-living (non-parasitic) phases.
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*Prepatent period 1week (embryonated egg, 50-60µm).
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*Infection by:
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**ingestion of L3 in mare's milk or grass; and
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**skin penetration.
  
 
==== Pathogenicity ====
 
==== Pathogenicity ====
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Pathology is rarely seen in adult horses due to the development of immunity, though penetration of the skin by larvae may still cause irritation anddermatitis. Adults with larvae in beneath the skin and in the abdomen can act as carriers. In foals heavy infections can cause severe enteritis and diarrhoea. It should be noted that apparently healthy animals can still have high faecal egg counts.
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*Foals - severe enteritis, diarrhoea (heavy burdens).
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Some clinical symptoms that may occur include: acute diarrhoea, loss of weight, coughing, dehydration, slight to moderate anaemia.
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*Adults - normally immune; may act as carriers, e.g. mare.
  
 
==== Control ====
 
==== Control ====
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The number and spread of ''S. westeri'' is best controlled by good hygeine such as the removal of faeces from pasture and stabling and the provision of clean, dry bedding. Foals are often treated with anthelmintics at 2 weeks old against ''S. westeri''.
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*Regular anthelmintic treatment.
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*Good hygiene.
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===''Strongyloides papillosus''===
 
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This is a nematode of cattle and small ruminants and is found throughout the world. As with ‘’S. westeri’’ above clinical signs are normally only seen in young animals as older animals develop immunity.
 
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====Morphology====
 
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The morphology of ''S. papillosus’’ is the same as that of the ‘’S. westeri’’. The eggs hatch inside the host and so L1 larvae are released with the faeces.
 
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====Life Cycle====
 
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The life cylce of ''S. papillosus'' is typical of [[:Category:Rhabditoidea|strongyloides]] species with both parasitic and free living cycles. As adults animals will become immune to infection the primary method of infection for young animals is through the milk of the dam, this still involves only females as males are only present in the environment as 'free-living' nematodes.
 
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[[Category:Rhabditoidea]][[Category:Horse Nematodes]][[Category:Sheep Nematodes]]
 
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[[Category:To_Do_-_Parasites]][[Category:To Do - Major]]
 

Revision as of 22:08, 26 April 2010

Strongyloides stercoralis - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine
Strongyloides stercoralis - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Strongyloides larvae - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Strongyloides - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona

STRONGYLOIDES WESTERI

General

  • Rhabditoid, small intestine.
  • Commonest in foals <6months old.
  • FIRST PARASITE TO WHICH FOALS ARE EXPOSED.

Morphology

  • <6mm long, similar to small trichostrongyles.
  • Only female worms parasitic.
  • Long oesophagus (up to one third of body length).

Life-Cycle

  • Parasitic and free-living (non-parasitic) phases.
  • Prepatent period 1week (embryonated egg, 50-60µm).
  • Infection by:
    • ingestion of L3 in mare's milk or grass; and
    • skin penetration.

Pathogenicity

  • Foals - severe enteritis, diarrhoea (heavy burdens).
  • Adults - normally immune; may act as carriers, e.g. mare.

Control

  • Regular anthelmintic treatment.
  • Good hygiene.
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