giardiasis (beaver fever)
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Etiology
Epidemiology
- both endemic & epidemic infections worldwide
- especially in travelers, campers, children & workers in day care centers & homosexual men
- infectious cysts live in the environment
- trophozyte attaches to the small intestine; responsible for symptoms in inected individuals
- infection generally occurs via drinking contaminated water
- Giardia is not killed by usual concentrations of chlorine in murine municipal water
- water supply must be filtered to eliminate Giardia
- campers must boil water from streams or lakes in endemic areas
- asymptomatic carriers common[6]
- person to person transmission from poor hygiene & sanitation occurs
Pathology
- trophozoites multiply in the small bowel & attach to the mucosa by a ventral concave sucking disc
- disruption of the brush border
- disaccharidase deficiency
Clinical manifestations
- infection may be asymptomatic (> 50%)
- variable symptoms from mild diarrhea with vague abdominal complaints to a syndrome of weight loss, abdominal distention, malabsorption, explosive watery diarrhea & steatorrhea
- fever is rare
- stool generally foul-smelling
- indefinite duration of symptoms if untreated; up to 3 weeks[6]
- prolonged traveler's diarrhea, especially after a camping trip[3]
Laboratory
- Giardia lamblia antigen in stool is the most sensitive assay
- fecal leukocytes & fecal occult blood may be negative[3]
- stool for ova & parasites
- diagnosis can be made by recovery of trophozoites or cysts in feces
- examination of multiple specimens may be required as passage of organisms in the feces is intermittent
- at least 3 specimens recommended
- small bowel aspirates or string test specimens may be required if trophozoites & cysts not found in feces (notify laboratory in advance)
- also see Giardia lamblia
- molecular diagnostic testing
Complications
- lactose deficiency
- common & may persist for months after acute infection
- may be confused with relapse of giardiasis or failure of symptoms to clear after appropriate antibiotics
- irritable bowel syndrome
Differential diagnosis
Management
- supportive management for diarrhea
- tinidazole 2 g PO considered more effective than metronidazole
- 1st line, treatment of choice[7]
- metronidazole
- nitazoxanide (Alinia)
- 500 PO BID with food for 3 days
- as effective as metronidazole[3]
- furazolidone 100 mg PO QID for 7-10 days
- prevention:
- boiling water in endemic areas
- iodine treatment of water
- water filtration system
More general terms
Additional terms
References
- ↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1277-78
- ↑ http://www.biosci.ohio-state.edu/~parasite/giardia.html
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Medical Knowledge Self Assessment Program (MKSAP) 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 2006, 2009, 2012, 2015, 2018, 2021.
Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022 - ↑ Pawlowski SW, Warren CA, Guerrant R. Diagnosis and treatment of acute or persistent diarrhea. Gastroenterology. 2009 May;136(6):1874-86 PMID: https://www.ncbi.nlm.nih.gov/pubmed/19457416
- ↑ Einarsson E, Ma'ayeh S, Svard SG. An up-date on Giardia and giardiasis. Curr Opin Microbiol. 2016 Dec;34:47-52. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/27501461
- ↑ 6.0 6.1 6.2 Grimm L What's Eating You: 12 Common Intestinal Parasites. Medscape. November 25, 2019 https://reference.medscape.com/slideshow/intestinal-parasites-6010996
- ↑ 7.0 7.1 NEJM Knowledge+ Gastroenterology
Minetti C, Chalmers RM, Beeching NJ, Probert C, Lamden K. Giardiasis. BMJ. 2016 Oct 27;355:i5369. PMID: https://www.ncbi.nlm.nih.gov/pubmed/27789441 Review. Free article