Ver el código de «Giardia lamblia»

==Background==
*Flagellated protozoan
*Most common cause of parasitic diarrhea worldwide
*Transmitted by water contaminated with feces (human, beaver, muskrat, dogs, raccoons, etc)
*Common among campers and is also known as “backpacker’s diarrhea”  
*Common in travelers to former Soviet Union, Caribbean, Latin America, India, Africa
*Infection rate is twice as high during summer months
*Also may be transmitted by contaminated food or close physical contact (sexual activity, daycare centers, etc)
*Patients with decreased gastric acidity, immunoglobulin deficiency, or immunocompromise are more susceptible 
*Other names: “beaver fever”, “the Trotskys” (common in travelers to Leningrad) <ref>Marx, John A., Robert S. Hockberger, Ron M. Walls, James Adams, and Peter Rosen. "Chapter 94 -- Gastroenteritis." Rosen's Emergency Medicine Concepts and Clinical Practice. Philadelphia: Mosby/Elsevier, 2010. Print.</ref> <ref>Tintinalli, Judith E., and J. Stephan. Stapczynski. "Chapter 156 -- World Traveler." Tintinalli's Emergency Medicine: A Comprehensive Study Guide. New York: McGraw-Hill, 2011. Print.</ref> <ref>Tintinalli, Judith E., and J. Stephan. Stapczynski. "Chapter 154 -- Foodborne and Waterborne Diseases." Tintinalli's Emergency Medicine: A Comprehensive Study Guide. New York: McGraw-Hill, 2011. Print.</ref>

===Pathophysiology===
*Trophozoites infect duodenum, jejunum, and ileum where they form cysts
*Cysts are passed in feces; viable for long periods of time
*A single diarrheal stool may contain hundreds of millions of cysts or parasites

==Clinical Presentation==
*Often asymptomatic
*Most common symptoms include:
**Abdominal distension
**Colicky pain
**Flatulence
**[[Diarrhea]] (pale, loose, floating, foul odor)
**Borborygmi
*No blood or mucus in stool
*Sudden onset after incubation period of 1-3 weeks
*Symptoms usually resolve in 7-10 days
*85% of the time infection resolves spontaneously within 6 weeks
*May cause chronic malabsorption-like illness, especially in those with immunoglobulin deficiency
*Chronic infections cause weight loss, anemia, lactose intolerance

==Differential Diagnosis==

*Viral infection (e.g. rotavirus)
*Bacterial diarrhea
**[[Campylobacter]]
**[[Shigella]]
**[[Salmonella]]
**[[E. Coli]]
**[[E. Coli O157:H7]]
**[[Yersinia]]
**[[Vibrio cholera]]
**[[Clostridium difficile]]
*Parasitic infection
**[[Cryptosporidium]]
**[[Enteromonas hominis]]
**[[Entamoeba histolytica]]
*Toxin-mediated
**[[Staphylococcus aureus]]
**[[Bacillus cereus]]

==Diagnosis==
*Normal WBC, no eosinophilia
*Stool O&P
**Motile trophozoites or cysts
**Able to diagnose infection readily in acute illness
**More difficult to diagnose in chronic or asymptomatic infection
*Antigen testing with ELISA, DFA, etc starting to replace microscopic examination with similar cost <ref>http://www.ncbi.nlm.nih.gov/pubmed/22632642</ref>
*Suspect protozoan illness in patients with diarrhea > 2 weeks

==Management==
''Treatment is not always successful <ref>http://www.ncbi.nlm.nih.gov/pubmed/20086650 </ref>''
*[[Metronidazole]]
**Adult: 250 mg TID x 7-10 days
**Children: 5 mg/kg TID x 7 days (max dose 500 mg TID)
*[[Albendazole]]<ref>http://www.ncbi.nlm.nih.gov/pubmed/23235648</ref>
**400 mg PO daily x 5-10 days
*Tinidazole
**Adult: 2 grams PO x 1 dose
**Children: 50 mg/kg PO x 1 dose
*Quinacrine
**> 8 years old: 100 mg TID x 7 days
**< 8 years old: 2 mg/kg TID x 7 days
*Nitazoxanide
**> 12 years old: 500 mg BID x 3 days
**4-11 years old: 200 mg BID x 3 days
**12-47 months old: 100 mg BID x 3 days

===Public Health Measures===
*Strict adherence to handwashing (toileting, diaper changes, playing with pets, etc)
*Treat household members and/or sexual contacts if infected
*Treat asymptomatic infections in those at high-risk of transmitting to others (children in daycare, food handlers, etc) or those at risk of chronic symptoms
*Reinfection universal within 3 months in heavily infected endemic areas; treatment is not cost-effective in this setting

==Disposition==
*Disease is usually self-limited
*Admit those with systemic symptoms, severe dehydration, inability to tolerate PO fluids, or those with significant co-morbidities
*Supplementation with zinc and probiotics reduce severity/duration of diarrhea <ref>http://www.ncbi.nlm.nih.gov/pubmed/23192407</ref>

==References==
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