Giardia duodenalis - Revision history

Aidan at 00:53, 12 February 2026

2026-02-12T00:53:49Z

← Older revision		Revision as of 00:53, 12 February 2026
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⚫	*A ~~member~~ of the [[Giardia]] that causes intestinal disease ('''giardiasis''') in humans and animals
⚫	*Also known as '''beaver fever'''

	==Background==		==Background==

		⚫	*A species of parasite within the genus [[Genus::Giardia]] that causes intestinal disease ('''giardiasis''') in humans and animals
		⚫	*Also known as '''beaver fever'''

	===Microbiology===		===Microbiology===
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	**May have malabsorption, often has weight loss		**May have malabsorption, often has weight loss
	**Symptoms can wax and wane, with periods of remission or constipation		**Symptoms can wax and wane, with periods of remission or constipation

			=== Post-Infectious Syndromes ===
	*'''Post-''Giardia'' syndrome''' with irritable bowel syndrome and chronic fatigue may last for years		*'''Post-''Giardia'' syndrome''' with irritable bowel syndrome and chronic fatigue may last for years
	**Can have significant malabsorption		**Can have significant malabsorption

Aidan at 18:02, 27 June 2025

2025-06-27T18:02:04Z

← Older revision		Revision as of 18:02, 27 June 2025
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	*Antigen assays are sometimes used during outbreaks or for screening		*Antigen assays are sometimes used during outbreaks or for screening
	**Sensitivity 85-98% and specificity 90-100%		**Sensitivity 85-98% and specificity 90-100%
	*PCR is becoming more common		*PCR is becoming more common, and is the current standard in Ontario
			**Becomes negative by about 7 days after successful treatment[[CiteRef::van den bijllaardt2014ra]]
	*String test		*String test
	**Put a string down into small bowel and then pull it back; it should have bile		**Put a string down into small bowel and then pull it back; it should have bile

Aidan at 14:09, 27 June 2025

2025-06-27T14:09:43Z

← Older revision		Revision as of 14:09, 27 June 2025
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	*[[Is treated by::Tinidazole]] 2 g po once, which is the gold standard		*[[Is treated by::Tinidazole]] 2 g po once, which is the gold standard
⚫	*[[Is treated by::Metronidazole]] 250 mg po tid for 5 to 7 days~~, but has a higher failure rate~~
	*[[Is treated by::Nitazoxanide]] 500 mg p.o. bid for 3 days		*[[Is treated by::Nitazoxanide]] 500 mg p.o. bid for 3 days
		⚫	*[[Is treated by::Metronidazole]] 250 mg po tid (or 500 mg bid) for 5 to 7 days
			**Has a higher failure rate
	*Alternatives: [[Is treated by::albendazole]], [[Is treated by::paromomycin]], [[Is treated by::quinacrine]], and [[Is treated by::furazolidone]]		*Alternatives: [[Is treated by::albendazole]], [[Is treated by::paromomycin]], [[Is treated by::quinacrine]], and [[Is treated by::furazolidone]]
			**[[Albendazole]] 400 mg p.o. daily for 5 days
			**[[Mebendazole]] 200 mg p.o. TID for 5 days
			**[[Paromomycin]] 10 mg/kg p.o. TID for 5 to 10 days
			**[[Furazolidone]] 100 mg p.o. QID for 7 to 10 days
			**[[Quinacrine]] 100 mg p.o. TID for 5 days
	*Avoid caffeine, lactose, and smoking		*Avoid caffeine, lactose, and smoking
	*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)		*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)

Aidan: /* Management */

2025-06-25T02:31:57Z

Management

← Older revision		Revision as of 02:31, 25 June 2025
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	*[[Is treated by::Tinidazole]] 2 g po once, which is the gold standard		*[[Is treated by::Tinidazole]] 2 g po once, which is the gold standard
	*[[Is treated by::Metronidazole]] 250 mg po tid for 5 to 7 days, but has a higher failure rate		*[[Is treated by::Metronidazole]] 250 mg po tid for 5 to 7 days, but has a higher failure rate
			*[[Is treated by::Nitazoxanide]] 500 mg p.o. bid for 3 days
	*Alternatives: ~~[[Is treated by::nitazoxanide]],~~ [[Is treated by::albendazole]], [[Is treated by::paromomycin]], [[Is treated by::quinacrine]], and [[Is treated by::furazolidone]]		*Alternatives: [[Is treated by::albendazole]], [[Is treated by::paromomycin]], [[Is treated by::quinacrine]], and [[Is treated by::furazolidone]]
	*Avoid caffeine, lactose, and smoking		*Avoid caffeine, lactose, and smoking
	*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)		*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)

Aidan at 02:05, 25 June 2025

2025-06-25T02:05:50Z

← Older revision		Revision as of 02:05, 25 June 2025
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	*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)		*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)

	{{DISPLAYTITLE:''Giardia ~~lamblia~~''}}		{{DISPLAYTITLE:''Giardia duodenalis''}}
	[[Category:Gastrointestinal infections]]		[[Category:Gastrointestinal infections]]
	[[Category:Flagellates]]		[[Category:Flagellates]]

Aidan: Aidan moved page Giardia lamblia to Giardia duodenalis

2025-06-25T02:05:35Z

Aidan moved page Giardia lamblia to Giardia duodenalis

← Older revision	Revision as of 02:05, 25 June 2025
(No difference)

Aidan: Text replacement - " species]]" to "]]"

2022-02-01T17:07:34Z

Text replacement - " species]]" to "]]"

← Older revision		Revision as of 17:07, 1 February 2022
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	*A member of the [[Giardia ~~species~~]] that causes intestinal disease ('''giardiasis''') in humans and animals		*A member of the [[Giardia]] that causes intestinal disease ('''giardiasis''') in humans and animals
	*Also known as '''beaver fever'''		*Also known as '''beaver fever'''

Aidan: categories

2020-08-07T14:22:11Z

categories

← Older revision		Revision as of 14:22, 7 August 2020
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	* A member of the [[Giardia species]] that causes intestinal disease ('''giardiasis''') in humans and animals		*A member of the [[Giardia species]] that causes intestinal disease ('''giardiasis''') in humans and animals
	* Also known as '''beaver fever'''		*Also known as '''beaver fever'''

	== Background ==		==Background==

	=== Microbiology ===		===Microbiology===

	* Flagellated protozoan that infects the small bowel		*Flagellated protozoan that infects the small bowel
	* Host specificity related to genotype ("assemblage")		*Host specificity related to genotype ("assemblage")
	** Assemblages A & B infect humans, but also numerous non-human hosts including primates, dogs, cats, cattle, sheep, deer, rodents, horses, and beavers		**Assemblages A & B infect humans, but also numerous non-human hosts including primates, dogs, cats, cattle, sheep, deer, rodents, horses, and beavers
	** Assemblages C & D affect dogs; E affects cattle, goats, sheep, and pigs; F affects cats; G affects rodents; and H affects marine vertebrates		**Assemblages C & D affect dogs; E affects cattle, goats, sheep, and pigs; F affects cats; G affects rodents; and H affects marine vertebrates
	* Antigenic variation is determined by the variant-specific surface protein (VSP)		*Antigenic variation is determined by the variant-specific surface protein (VSP)
	** Replaced every few generations		**Replaced every few generations

	=== Life Cycle ===		===Life Cycle===

	* A cyst is ingested via fecal-oral contamination		*A cyst is ingested via fecal-oral contamination
	* In the small bowel, the cyst releases two trophozoites (free-living form) via excystation		*In the small bowel, the cyst releases two trophozoites (free-living form) via excystation
	* Trophozoites multiply by binary fission		*Trophozoites multiply by binary fission
	* When they reach the large bowel, they encyst		*When they reach the large bowel, they encyst

	=== Epidemiology ===		===Epidemiology===

	* Worldwide distribution		*Worldwide distribution
	* Generally transmitted fecal-oral route (via environment), but person-to-person transmission is possible in daycares		*Generally transmitted fecal-oral route (via environment), but person-to-person transmission is possible in daycares
	* Numerous animal reservoirs, not fully understood how important they are		*Numerous animal reservoirs, not fully understood how important they are
	* Cysts can survive several months in cold water		*Cysts can survive several months in cold water
	* Peak prevalence occurs in children of up to 15 to 30% in poor countries		*Peak prevalence occurs in children of up to 15 to 30% in poor countries
	* Reinfection is common		*Reinfection is common

	=== Pathophysiology ===		===Pathophysiology===

	* Infected with as few as 10 to 25 cysts		*Infected with as few as 10 to 25 cysts
	* Trophozoites colonize the upper small bowel, adhering to the mucosal enterocytes		*Trophozoites colonize the upper small bowel, adhering to the mucosal enterocytes
	* Host response involves B- and T-cells, including production of IgM and IgG antibodies, possibly IgA antibodies as well		*Host response involves B- and T-cells, including production of IgM and IgG antibodies, possibly IgA antibodies as well
	* Causes villous atrophy, which can contribute to malabsorption		*Causes villous atrophy, which can contribute to malabsorption
	* Inhibits disaccharidases, which contributes to lactose intolerance		*Inhibits disaccharidases, which contributes to lactose intolerance

	== Clinical Manifestations ==		==Clinical Manifestations==

	* Can have '''asymptomatic cyst passage''' (5 to 15%)		*Can have '''asymptomatic cyst passage''' (5 to 15%)
	** Can last up to 6 months in children		**Can last up to 6 months in children
	* Most common syndrome is '''acute diarrhea''' (25 to 50%)		*Most common syndrome is '''acute diarrhea''' (25 to 50%)
	** Incubation period [[Usual incubation period::1 to 2 weeks]]		**Incubation period [[Usual incubation period::1 to 2 weeks]]
	** Usually presents after 7 to 10 days		**Usually presents after 7 to 10 days
	** Malaise, flatulence, cramps, bloating, nausea, anorexia, vomiting, and malabsorption		**Malaise, flatulence, cramps, bloating, nausea, anorexia, vomiting, and malabsorption
	** '''Sulfuric belching''' is classic		**'''Sulfuric belching''' is classic
	** Fevers are uncommon but possible		**Fevers are uncommon but possible
	* Can also cause '''chronic diarrhea'''		*Can also cause '''chronic diarrhea'''
	** More common in [[CVID]], [[X-linked agammaglobulinemia]], and [[AIDS]]		**More common in [[CVID]], [[X-linked agammaglobulinemia]], and [[AIDS]]
	** Malaise, occasional headache, diffuse abdominal and epigastric pain worse with food		**Malaise, occasional headache, diffuse abdominal and epigastric pain worse with food
	** May have malabsorption, often has weight loss		**May have malabsorption, often has weight loss
	** Symptoms can wax and wane, with periods of remission or constipation		**Symptoms can wax and wane, with periods of remission or constipation
	* '''Post-''Giardia'' syndrome''' with irritable bowel syndrome and chronic fatigue may last for years		*'''Post-''Giardia'' syndrome''' with irritable bowel syndrome and chronic fatigue may last for years
	** Can have significant malabsorption		**Can have significant malabsorption
	* Also, can have '''post-''Giardia'' lactose intolerance''' lasting several weeks		*Also, can have '''post-''Giardia'' lactose intolerance''' lasting several weeks

	== Diagnosis ==		==Diagnosis==

	* Stool microscopy		*Stool microscopy
	** May see active trophozoites in saline wet prep		**May see active trophozoites in saline wet prep
	** Look for cysts after iodine staining		**Look for cysts after iodine staining
	** Sensitivity 60-80% with one stool sample, up to 90% with three		**Sensitivity 60-80% with one stool sample, up to 90% with three
	* Antigen assays are sometimes used during outbreaks or for screening		*Antigen assays are sometimes used during outbreaks or for screening
	** Sensitivity 85-98% and specificity 90-100%		**Sensitivity 85-98% and specificity 90-100%
	* PCR is becoming more common		*PCR is becoming more common
	* String test		*String test
	** Put a string down into small bowel and then pull it back; it should have bile		**Put a string down into small bowel and then pull it back; it should have bile
	** Look with a microscope		**Look with a microscope
	** Done when there is high suspicion but O&P negative		**Done when there is high suspicion but O&P negative

	== Management ==		==Management==

	* [[Is treated by::Tinidazole]] 2 g po once, which is the gold standard		*[[Is treated by::Tinidazole]] 2 g po once, which is the gold standard
	* [[Is treated by::Metronidazole]] 250 mg po tid for 5 to 7 days, but has a higher failure rate		*[[Is treated by::Metronidazole]] 250 mg po tid for 5 to 7 days, but has a higher failure rate
	* Alternatives: [[Is treated by::nitazoxanide]], [[Is treated by::albendazole]], [[Is treated by::paromomycin]], [[Is treated by::quinacrine]], and [[Is treated by::furazolidone]]		*Alternatives: [[Is treated by::nitazoxanide]], [[Is treated by::albendazole]], [[Is treated by::paromomycin]], [[Is treated by::quinacrine]], and [[Is treated by::furazolidone]]
	* Avoid caffeine, lactose, and smoking		*Avoid caffeine, lactose, and smoking
	* Can consider [[Saccharomyces boulardii]] probiotics (Florastor)		*Can consider [[Saccharomyces boulardii]] probiotics (Florastor)

	{{DISPLAYTITLE:''Giardia lamblia''}}		{{DISPLAYTITLE:''Giardia lamblia''}}
⚫	[[Category:~~Protozoa~~]]
	[[Category:Gastrointestinal infections]]		[[Category:Gastrointestinal infections]]
		⚫	[[Category:Flagellates]]
			[[Category:Infectious diseases]]

Aidan: /* Clinical Manifestations */

2020-08-05T13:56:27Z

Clinical Manifestations

← Older revision		Revision as of 13:56, 5 August 2020
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	** Can last up to 6 months in children		** Can last up to 6 months in children
	* Most common syndrome is '''acute diarrhea''' (25 to 50%)		* Most common syndrome is '''acute diarrhea''' (25 to 50%)
	** Incubation period 1 to 2 weeks		** Incubation period [[Usual incubation period::1 to 2 weeks]]
	** Usually presents after 7 to 10 days		** Usually presents after 7 to 10 days
	** Malaise, flatulence, cramps, bloating, nausea, anorexia, vomiting, and malabsorption		** Malaise, flatulence, cramps, bloating, nausea, anorexia, vomiting, and malabsorption

Aidan: Text replacement - "Clinical Presentation" to "Clinical Manifestations"

2020-07-23T04:07:45Z

Text replacement - "Clinical Presentation" to "Clinical Manifestations"

← Older revision		Revision as of 04:07, 23 July 2020
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	* Inhibits disaccharidases, which contributes to lactose intolerance		* Inhibits disaccharidases, which contributes to lactose intolerance

	== Clinical ~~Presentation~~ ==		== Clinical Manifestations ==

	* Can have '''asymptomatic cyst passage''' (5 to 15%)		* Can have '''asymptomatic cyst passage''' (5 to 15%)