Difference between revisions of "Giardia"

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|sub-order          =
 
|sub-order          =
 
|super-family      =
 
|super-family      =
|family            =
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|family            =Diplomonadidae
 
|sub-family        =
 
|sub-family        =
 
|genus              =Giardia
 
|genus              =Giardia
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[[Image:Giardia.jpg|thumb|right|150px|''Giardia'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Giardia.jpg|thumb|right|150px|''Giardia'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]
 
[[Image:Giardia cyst.jpg|thumb|right|150px|''Giardia'' cyst - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
 
[[Image:Giardia cyst.jpg|thumb|right|150px|''Giardia'' cyst - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine]]
 +
==Overview==
 +
These protozoan parasite are found in humans as well as wild and domestic animals. They are a common cause of severe [[Diarrhoea|diarrhoea]].
 +
 
==Recognition==
 
==Recognition==
  
*Flagellate protozoa
+
''Giardia spp.'' are flagellate protozoa with 8 flagella, 6 of which emerge from the body and are used in motility. They are 15-20μm long, pear shaped with a flat ventral surface. The most unique feature of this protozoa is the presence of a large adhesive disk in the flat surface that is used for attaching to the intestinal mucosa.
  
*Found in the intestine of humans
+
==Life Cycle==
  
*Associated with chronic [[Diarrhoea|diarrhoea]]
 
  
*Found in both wild and domestic animals
 
 
*15-20μm long
 
 
*Pear-shaped
 
 
*8 flagella
 
**6 flagellae are free
 
 
*Large adhesive discs to hold onto intestinal mucosa
 
 
==Life Cycle==
 
  
 
*Simple and direct
 
*Simple and direct
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***Some subspecies are zoonotic
 
***Some subspecies are zoonotic
  
==Diagnosis==
 
 
*Faecal examination
 
**Cysts need to be distinguished from pollen grains and yeasts
 
 
*Cyst excretion is intermittent
 
**Faeces need to be collected over a 3 day period
 
 
*Cysts are '''heavy'''
 
**Needs higher density flotation fluids
 
**Do not float well in saturated sodium chloride solution
 
 
*Immunoassays
 
**Detect cyst antigen in faeces
 
 
==Control and Treatment==
 
 
*Sanitation and hygiene
 
**Minimise risk of human infection
 
 
*Boil (or sterilise through other means) drinking water in regions of the world where drinking water may be contaminated
 
 
*Avoid uncooked foodstuffs
 
**Contaminated by washing
 
 
*[[Ectoparasiticides|Drug Treatments]]
 
**Metronidazole
 
***Flagyl, Torgyl
 
**Fenbendazole
 
***Panacur
 
 
*[[Vaccines - WikiBlood|Vaccination]]
 
**Killed trophozoites
 
**Available in the USA for cats and dogs
 
**Decreases the excretion and viability of cysts
 
**Decreases environmental pressure
 
  
 
<big>'''[[Giardia Flashcards]]</big>
 
<big>'''[[Giardia Flashcards]]</big>

Revision as of 23:17, 6 August 2010



Giardia
Kingdom Protista
Sub-kingdom Biciliata
Phylum Metamonada
Super-class Eopharyngea
Class Trepomonadea
Sub-class Diplozoa
Order Giardiida
Family Diplomonadidae
Genus Giardia
Giardia lamblia life cycle - Wikimedia Commons
Giardia lamblia - Janice Carr
Giardia - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona
Giardia cyst - Courtesy of the Laboratory of Parasitology, University of Pennsylvania School of Veterinary Medicine

Overview

These protozoan parasite are found in humans as well as wild and domestic animals. They are a common cause of severe diarrhoea.

Recognition

Giardia spp. are flagellate protozoa with 8 flagella, 6 of which emerge from the body and are used in motility. They are 15-20μm long, pear shaped with a flat ventral surface. The most unique feature of this protozoa is the presence of a large adhesive disk in the flat surface that is used for attaching to the intestinal mucosa.

Life Cycle

  • Simple and direct
  • Trophozoites attach to intestinal wall
  • Reproduce by binary fission
  • Form cysts of 10μm
    • Multi-nucleate cysts formed intermittently
    • Immediately infective when passed in faeces
  • Prepatent period of 5-6 days

Pathogenesis

  • Commonest cause of protozoal diarrhoea of man in the UK
  • Common in domesticated animals
  • Infections often asymptomatic in domestic animals
    • Can cause villous atrophy leading to malabsorption
    • Infection can persist for weeks to months if not treated

Epidemiology

  • Infection via direct oral-faecal route or through contaminated water source (water-borne)
  • Wild animals may act as a source of infection for humans
    • E.g. Beavers
  • Divided into 7 species
    • G. duodenalis most commonly infects humans
      • Some subspecies are zoonotic


Giardia Flashcards