Giardiasis

Giardiasis: Excerpt from The 5-Minute Pediatric Consult

Alan D. Baldridge, MD

Giardiasis - BASICS

Giardiasis - description

Symptomatic infection of duodenum and jejunum with flagellated protozoan Giardia lamblia

Giardiasis - general prevention

• Maintenance of good sanitary conditions (strict handwashing and diaper disposal)
• Breast-feeding
• Family members and close contacts should be examined and treated if necessary.
• Examine water source in endemic areas.
• Boiling or iodine-based water treatment for camping and hiking

Giardiasis - epidemiology

• ~2.5 million cases of infection annually in the US
• Peaks at ages 0–5 years; 2nd peak at ages 31–40 years
• More common in spring and summer
• Water-dwelling mammals and household pets can become infected and may serve as reservoir of infection.

Giardiasis - incidence

Average in US 9.5 cases per 100,000

Giardiasis - prevalence

• Direct person-to-person transmission accounts for the very high prevalence rates in institutions, daycare centers, and family contacts.
• High prevalence rates have been reported in patients with cystic fibrosis as well as Crohn disease.
• Waterborne transmission is an important source of endemic or epidemic spread, especially when water is supplied by surface source such as streams and reservoirs (outdoor recreation and international travel).
• Foodborne infection is uncommon and generally from uncooked or undercooked food or food contaminated after cooking by water source.

Giardiasis - risk factors

• Day care attendance
• International adoption
• Hypochlorhydria (previous gastric surgery)
• Hypogammaglobulinemia/immunodeficiency
• Blood group A
• Certain human leukocyte antigen alleles

Giardiasis - etiology

• G. lamblia:
  • 2 form life cycle: Cyst (transmission) and trophozoite (infection)
  • Trophozoites adhere to duodenal mucosa with a ventral disk leading to mucosal damage and symptoms. Organism is noninvasive and does not lead to mucosal necrosis.
  • Cyst formation occurs in the colon and is passed into the environment. It can survive for a prolonged time if moist.
• Infection occurs after cyst ingestion from fecally contaminated water or by direct fecal–oral transmission in poor sanitary conditions; ingestion of between 10 and 100 cysts can produce infection.
• Anti-Giardia properties in breast milk may be related to free fatty acids cleaved from milk triglyceride by a bile salt–stimulated lipase present in human milk.
• Giardia also exhibits antigenic variation over the course of an infection.
• Mechanism of diarrhea is poorly understood but could include:
  • A glycoprotein located on the surface of G. lamblia trophozoites has been demonstrated to induce fluid accumulation in ligated ileal loops in rabbits.
  • Giardiasis results in decreased jejunal electrolyte, water, and 3-O-methyl-D-glucose absorption, thus leading to electrolyte, solute, and fluid malabsorption.
  • Damage to the intestinal brush border and the corresponding decrease in disaccharidase activity may lead to increased quantities of disaccharides in the intestinal lumen, which can result in osmotic diarrhea.
  • Giardia infection in gerbils accelerates intestinal transit time and increases smooth muscle contractility, both of which may play a role in giardial diarrhea.

Giardiasis - DIAGNOSIS

Giardiasis - signs & symptoms

• Most (60%) infected individuals are asymptomatic.
• Common manifestations:
  • Sudden-onset watery, foul-smelling diarrhea without blood
  • Abdominal cramps
  • Bloating/flatulence
  • Anorexia
  • Dyspepsia
  • Nausea
  • Malaise
• Chronic course is associated with:
  • Weight loss
  • Loose, semiformed stool
  • Abdominal distention
  • Anorexia
  • Flatulence
  • Depression
• Malabsorption syndrome may include:
  • Steatorrhea
  • Secondary lactase deficiency
  • Deficiencies of iron, folic acid, vitamins A, BProtein-losing enteropathy

Giardiasis - history

• Exposure to well water
• Habitation in endemic area, institution
• Asymptomatic infection can occur.
• Camping or hiking near fresh water
• Exposure to infected individual
• Immune function

Giardiasis - physical exam

• Abdominal distention
• Aphthous ulcers in oral mucosa
• Urticaria
• Arthralgia/Arthritis

Giardiasis - tests

Giardiasis - lab

• Stool microscopy for detection of cysts and/or trophozoite
• Commercial ELISA test for detection of G. lamblia antigen in stools is available.
• Empiric therapeutic trail of antiparasitic therapy in endemic area or populations
• If immunodeficiency is suspected, check immune function, especially IgA.

Giardiasis - diag proced-surgery

If strong suspicion of giardiasis, but 3 negative stool samples:

• Small intestinal aspirate sample may be obtained from duodenum.
• Duodenal biopsy specimen appears to be most sensitive.

Giardiasis - pathological findings

Mucosal lesions vary from normal to subtotal villus atrophy with crypt hyperplasia and proliferation of intraepithelial and lamina propria lymphocytes. Trophozoite may be seen on biopsies as an S-like curled shape on longitudinal sections.

Giardiasis - differencial diagnosis

• Celiac disease
• Cystic fibrosis
• Lactose intolerance
• Irritable bowel syndrome
• Inflammatory bowel disease
• Nonulcer dyspepsia

Giardiasis - TREATMENT

Giardiasis - general measures

Giardiasis - diet

• High fiber diet may aid in clearance.
• Low lactose diet to prevent bloating and diarrhea for 1 month after treatment
• Probiotics may aid in prevention and clearance of infection.

Giardiasis - medication

• Metronidazole (not approved by FDA)
  • Most effective and best tolerated
  • Dose: 15 mg/kg/d divided t.i.d. for 7 days
• Tinidazole (approved for children ≥3 years)
  • 50 mg/kg to 2 g single dose
  • Available in tablet form only
• Nitazoxanide (approved for ages 1–11 years)
• Furazolidone: Lower efficacy but better tolerated than metronidazole
• Asymptomatic giardiasis, in absence of risk factors, should not be treated. Household contacts of pregnant or immunocompromised persons may be considered.
• Repeat ova and parasite examination and antigen detection with recurrence of symptoms.
• May need to test for cure in patients with multiple organism infections

Giardiasis - FOLLOW UP

Giardiasis - prognosis

• Remains good for symptomatic patients
• Combination therapy with 2 medications has been successful when repeated courses of single drug have failed.

Giardiasis - complications

• Malabsorption syndrome
• Steatorrhea
• Lactose deficiency
• Deficiencies of iron, folic acid, and vitamins A, BProtein-losing enteropathy
• Urticaria
• Arthralgia
• Growth retardation

Giardiasis - patient monitoring

• Incubation period usually 1–2 weeks
• Reinfection common if source not eradicated
• If symptoms persist, with negative diagnostic studies, consider alternative etiology or another enteropathogen.

Giardiasis - bibliography

1. Ali SA, Hill DR. Giardia intestinalis. Curr Opin Infect Dis. 2003;16:453–460.
2. Bartlett AV, Englender SJ, Jarvis BA, et al. Controlled trial of Giardia lamblia: Control strategies in day care centers. Am J Public Health. 1991;81:1001–1006.
3. Buret A, Hardin JA, Olson ME, et al. Pathophysiology of small intestinal malabsorption in gerbils infected with Giardia lamblia. Gastroenterology. 1992;103:506–513.
4. Furness BW, Beach MJ, Roberts JM. Giardiasis surveillance—United States, 1992–1997. MMWR CDC Surveill Summ. 2000;49(7):1–13.
5. Gardner TB, Hill DR. Treatment of giardiasis. Clin Microbiol Rev. 2001;14:114–128.
6. Katz DE, Taylor DN. Parasitic infections of the gastrointestinal tract. Gastroenterol Clin North Am. 2001;30:797–815.
7. Kaur H, Ghosh S, Samra H, et al. Identification and characterization of an excretory-secretory product from Giardia lamblia. Parasitology. 2001;123:347–356.
8. Leitch GJ, Visvesvara GS, Wahlquist SE, et al. Dietary fiber and giardiasis: Dietary fiber reduces rate of intestinal infection by Giardia lamblia in the gerbil. Am J Trop Med Hyg. 1989;41:512–520.
9. Long KZ, Santos JI, Rosado JL, et al. Impact of vitamin A on selected gastrointestinal pathogen infections and associated diarrheal episodes among children in Mexico City, Mexico. J Infect Dis. 2006;194(9):1217–1225. Epub 2006 Sep 26.
10. Ortega YR, Adam RD. Giardia: Overview and update. Clin Infect Dis. 1997;25:545–549.
11. Zimmerman SK, Needham CA. Comparison of conventional stool concentration and preserved-smear methods with Merifluor Cryptosporidium/Giardia Direct immunofluorescence Assay and ProSpecT Giradia EZ Microplate assay for detection of Giardia lamblia. J Clin Microbiol. 1995;33:1942–1943.

Giardiasis - CODES

Giardiasis - icd9

007.1 Giardiasis

Giardiasis - FAQ

• Q: Where is a likely place that Giardia lamblia occurs?
• A: Well water is a common place.
• Q: What do I do if I suspect Giardia, but the stool sample is negative?
• A: Three samples are needed. If you are in an endemic area, you may choose to treat empirically.

Book Source Details

• Book Title: The 5-Minute Pediatric Consult
• Author(s): M. William Schwartz MD; et al.
• Year of Publication: 2008
• Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.

More About Giardia

• Back to disease: Giardia: Introduction
• Next Book Extract About Giardia: Surveys relating to Giardia
• More Book Extracts: All Online Books for Giardia

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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: The 5-Minute Pediatric Consult Authors: M. William Schwartz MD; et al. Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7577-9

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