Difference between revisions of "Giardia"

Revision as of 09:11, 7 January 2009

PARASITES PROTOZOA

Recognition

Giardia cysts from gerbil faecea - H.D.A. Lindquist, U.S. EPA

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

Flagellate protozoa

Found in the intestine of humans

Associated with chronic 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

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

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

Drug Treatments
- Metronidazole
  - Flagyl, Torgyl
- Fenbendazole
  - Panacur

Vaccination
- Killed trophozoites
- Available in the USA for cats and dogs
- Decreases the excretion and viability of cysts
- Decreases environmental pressure

@@ Line 1: / Line 1: @@
-{{Taxobox
+{{review}}
-|name               =Giardia
-|kingdom            =Protista
+{{toplink
-|sub-kingdom        =Biciliata
+|backcolour =
-|phylum             =Metamonada
+|linkpage =Parasites
-|super-class        =Eopharyngea
+|linktext =PARASITES
-|class              =Trepomonadea
+|pagetype=Bugs
-|sub-class          =Diplozoa
+|sublink1=Protozoa
-|super-order        =
+|subtext1=PROTOZOA
-|order              =Giardiida
-|sub-order          =
-|super-family       =
-|family             =Diplomonadidae
-|sub-family         =
-|genus              =Giardia
-|species            =
 }}
-[[Image:Giardia lamblia life cycle.jpg|thumb|right|150px|''Giardia lamblia life cycle'' - Wikimedia Commons]]
+<br>
+==Recognition==
+[[Image:Giardia cysts.jpg|thumb|right|150px|''Giardia'' cysts from gerbil faecea - H.D.A. Lindquist, U.S. EPA]]
+[[Image:Giardia lamblia life cycle.jpg|thumb|right|150px|''Giardia lamblia'' life cycle - Wikimedia Commons]]
 [[Image:Giardia lamblia.jpg|thumb|right|150px|''Giardia lamblia'' - Janice Carr]]
 [[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]]
-==Overview==
+*Flagellate protozoa
-These protozoan parasite are found in humans as well as wild and domestic animals. They are a common cause of severe [[Diarrhoea|diarrhoea]] as part of the clinical symptoms [[Giardiasis|giardiasis]].
-==Recognition==
+*Found in the intestine of humans
+*Associated with chronic [[Intestine Diarrhoea - Pathology|diarrhoea]]
+*Found in both wild and domestic animals
+*15-20μm long
-''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.
+*Pear-shaped
-==Life Cycle==
+*8 flagella
+**6 flagellae are free
+*Large adhesive discs to hold onto intestinal mucosa
+==Life Cycle==
 *Simple and direct
@@ Line 45: / Line 49: @@
 ==Pathogenesis==
-*Commonest cause of protozoal [[Diarrhoea|diarrhoea]] of man in the UK
+*Commonest cause of protozoal [[Intestine Diarrhoea - Pathology|diarrhoea]] of man in the UK
 *Common in domesticated animals
@@ Line 64: / Line 68: @@
 ***Some subspecies are zoonotic
-{{Learning
+==Diagnosis==
-|flashcards = [[Giardia_Flashcards|Giardia Flashcards]]
-|Vetstream = [https://www.vetstream.com/canis/search?s=protozoa Protozoa]
+*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
-{{unfinished}}
+*[[Vaccines - WikiBlood|Vaccination]]
-[[Category:Miscellaneous_Protozoa]]
+**Killed trophozoites
-[[Category:To_Do_-_Parasites]]
+**Available in the USA for cats and dogs
+**Decreases the excretion and viability of cysts
+**Decreases environmental pressure