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Treatment and prevention of giardiasis

Flor M Munoz, MD, MSc
Section Editors
Peter F Weller, MD, MACP
Sheldon L Kaplan, MD
Deputy Editor
Elinor L Baron, MD, DTMH


Giardia lamblia (also known as G. duodenalis or G. intestinalis) is a flagellated protozoan parasite [1-3]. G. lamblia causes both epidemic and sporadic disease and is an important etiology of waterborne and foodborne diarrhea, day-care center outbreaks, and diarrhea in international travelers and adoptees [1]. The treatment and prevention of giardiasis will be reviewed here. The life cycle, epidemiology, clinical manifestations, and diagnosis of giardiasis are discussed separately. (See "Giardiasis: Epidemiology, clinical manifestations, and diagnosis".)


Supportive measures for the treatment of individuals with symptomatic giardiasis are largely related to correction of fluid and electrolyte abnormalities that result from the diarrhea. (See "Clinical assessment and diagnosis of hypovolemia (dehydration) in children" and "Treatment of hypovolemia (dehydration) in children" and "Oral rehydration therapy".)


Indications — Symptomatic patients with giardiasis should be treated with antimicrobial therapy. Symptoms include diarrhea, malaise, steatorrhea, abdominal cramps, bloating, flatulence, nausea, and, especially in young children, weight loss and failure to thrive. (See "Giardiasis: Epidemiology, clinical manifestations, and diagnosis", section on 'Clinical manifestations'.)

Patients with giardiasis should be counseled to avoid lactose-containing foods for at least one month after therapy [4]. Acquired lactose intolerance occurs in up to 20 to 40 percent of cases and can take weeks or many months to resolve even after parasite clearance [5]. (See "Giardiasis: Epidemiology, clinical manifestations, and diagnosis".)

Treatment is not usually recommended for asymptomatic individuals [6,7]. However, treatment may be warranted to prevent the spread of infection if a patient is a household contact of a pregnant woman, an immunocompromised individual (especially in the setting of hypogammaglobulinemia), or a child in a day-care or other setting who might transmit infection to others [6,8]. (See 'Prevention' below.)

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Literature review current through: Oct 2017. | This topic last updated: Jun 20, 2017.
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  1. Kappus KD, Lundgren RG Jr, Juranek DD, et al. Intestinal parasitism in the United States: update on a continuing problem. Am J Trop Med Hyg 1994; 50:705.
  2. Musher DM, Musher BL. Contagious acute gastrointestinal infections. N Engl J Med 2004; 351:2417.
  3. Yoder JS, Harral C, Beach MJ, Centers for Disease Control and Prevention (CDC). Giardiasis surveillance - United States, 2006-2008. MMWR Surveill Summ 2010; 59:15.
  4. Hill DR, Nash TE. Intestinal flagellate and ciliate infections. In: Tropical Infectious Diseases: Principles, Pathogens and Practice, 3rd ed, Guerrant RL, Walker DA, Weller PF (Eds), Saunders Elsevier, Philadelphia 2011. p.623.
  5. Farthing MJ. Giardiasis. Gastroenterol Clin North Am 1996; 25:493.
  6. American Academy of Pediatrics. Giardia intestinalis (formerly Giardia lamblia and Giardia duodenalis) infections. In: Red Book: 2015 Report of the Committee on Infectious Diseases, 30th, Kimberlin DW, Brady MT, Jackson MA, Long SS (Eds), American Academy of Pediatrics, Elk Grove Village, IL 2015. p.353.
  7. Gilman RH, Marquis GS, Miranda E, et al. Rapid reinfection by Giardia lamblia after treatment in a hyperendemic Third World community. Lancet 1988; 1:343.
  8. Gardner TB, Hill DR. Treatment of giardiasis. Clin Microbiol Rev 2001; 14:114.
  9. Granados CE, Reveiz L, Uribe LG, Criollo CP. Drugs for treating giardiasis. Cochrane Database Syst Rev 2012; 12:CD007787.
  10. Cañete R, Escobedo AA, González ME, et al. A randomized, controlled, open-label trial of a single day of mebendazole versus a single dose of tinidazole in the treatment of giardiasis in children. Curr Med Res Opin 2006; 22:2131.
  11. Lalle M. Giardiasis in the post genomic era: treatment, drug resistance and novel therapeutic perspectives. Infect Disord Drug Targets 2010; 10:283.
  12. Rossignol JF, Lopez-Chegne N, Julcamoro LM, et al. Nitazoxanide for the empiric treatment of pediatric infectious diarrhea. Trans R Soc Trop Med Hyg 2012; 106:167.
  13. Chandy E, McCarthy J. Evidence behind the WHO guidelines: Hospital care for children: What is the most appropriate treatment for giardiasis? J Trop Pediatr 2009; 55:5.
  14. Tan, TQ. Giardiasis. In: Textbook of Pediatric Infectious Diseases, 6th ed, Feigin, RD, Cherry, JD, Demmler-Harrison, GJ, Kaplan, SL (Eds), Saunders, Philadelphia, 2009. p. 2852.
  15. Drugs for Parasitic Infections, 3rd Ed, The Medical Letter, New Rochelle, NY 2013.
  16. Tinidazole (Tindamax) - a new anti-protozoal drug. Med Lett Drugs Ther 2004; 46:70.
  17. Presutti antiprotozoal agent Tindamax clears FDA; AWP is $18 per dose. In: "The Pink Sheet" vol 66, F-D-C Reports, Inc. Chevy Chase, MD 2004. p.10.
  18. Speelman P. Single-dose tinidazole for the treatment of giardiasis. Antimicrob Agents Chemother 1985; 27:227.
  19. Escobedo AA, Núñez FA, Moreira I, et al. Comparison of chloroquine, albendazole and tinidazole in the treatment of children with giardiasis. Ann Trop Med Parasitol 2003; 97:367.
  20. Pengsaa K, Limkittikul K, Pojjaroen-anant C, et al. Single-dose therapy for giardiasis in school-age children. Southeast Asian J Trop Med Public Health 2002; 33:711.
  21. Escobedo AA, Alvarez G, González ME, et al. The treatment of giardiasis in children: single-dose tinidazole compared with 3 days of nitazoxanide. Ann Trop Med Parasitol 2008; 102:199.
  22. Fung HB, Doan TL. Tinidazole: a nitroimidazole antiprotozoal agent. Clin Ther 2005; 27:1859.
  23. American Academy of Pediatrics. Drugs for parasitic infections. In: Red Book: 2015 Report of the Committee on Infectious Diseases, 30th, Kimberlin DW, Brady MT, Jackson MA, Long SS (Eds), American Academy of Pediatrics, Elk Grove Village, IL 2015. p.927.
  24. Romark Alinia adult dose 'approvable'; anti-parasitic approved for children. In: "The Pink Sheet," Vol 64, No 48, F-D-C Reports, Inc, Chevy Chase, MD 2002. p.11.
  25. Ortiz JJ, Ayoub A, Gargala G, et al. Randomized clinical study of nitazoxanide compared to metronidazole in the treatment of symptomatic giardiasis in children from Northern Peru. Aliment Pharmacol Ther 2001; 15:1409.
  26. Rossignol JF, Ayoub A, Ayers MS. Treatment of diarrhea caused by Giardia intestinalis and Entamoeba histolytica or E. dispar: a randomized, double-blind, placebo-controlled study of nitazoxanide. J Infect Dis 2001; 184:381.
  27. Davila-Gutierrez CE, Vasquez C, Trujillo-Hernandez B, Huerta M. Nitazoxanide compared with quinfamide and mebendazole in the treatment of helminthic infections and intestinal protozoa in children. Am J Trop Med Hyg 2002; 66:251.
  28. Diaz E, Mondragon J, Ramirez E, Bernal R. Epidemiology and control of intestinal parasites with nitazoxanide in children in Mexico. Am J Trop Med Hyg 2003; 68:384.
  29. Nitazoxanide (Alinia)--a new anti-protozoal agent. Med Lett Drugs Ther 2003; 45:29.
  30. Cohen SA. Use of nitazoxanide as a new therapeutic option for persistent diarrhea: a pediatric perspective. Curr Med Res Opin 2005; 21:999.
  31. Hall A, Nahar Q. Albendazole as a treatment for infections with Giardia duodenalis in children in Bangladesh. Trans R Soc Trop Med Hyg 1993; 87:84.
  32. Misra PK, Kumar A, Agarwal V, Jagota SC. A comparative clinical trial of albendazole versus metronidazole in giardiasis. Indian Pediatr 1995; 32:291.
  33. Dutta AK, Phadke MA, Bagade AC, et al. A randomised multicentre study to compare the safety and efficacy of albendazole and metronidazole in the treatment of giardiasis in children. Indian J Pediatr 1994; 61:689.
  34. Solaymani-Mohammadi S, Genkinger JM, Loffredo CA, Singer SM. A meta-analysis of the effectiveness of albendazole compared with metronidazole as treatments for infections with Giardia duodenalis. PLoS Negl Trop Dis 2010; 4:e682.
  35. Canete R, Escobedo AA, Gonzalez ME, Almirall P. Randomized clinical study of five days apostrophe therapy with mebendazole compared to quinacrine in the treatment of symptomatic giardiasis in children. World J Gastroenterol 2006; 12:6366.
  36. Escobedo AA, Cañete R, Gonzalez ME, et al. A randomized trial comparing mebendazole and secnidazole for the treatment of giardiasis. Ann Trop Med Parasitol 2003; 97:499.
  37. Sadjjadi SM, Alborzi AW, Mostovfi H. Comparative clinical trial of mebendazole and metronidazole in giardiasis of children. J Trop Pediatr 2001; 47:176.
  38. Craft JC, Murphy T, Nelson JD. Furazolidone and quinacrine. Comparative study of therapy for giardiasis in children. Am J Dis Child 1981; 135:164.
  39. Requena-Méndez A, Goñi P, Rubio E, et al. The Use of Quinacrine in Nitroimidazole-resistant Giardia Duodenalis: An Old Drug for an Emerging Problem. J Infect Dis 2017; 215:946.
  40. Hanevik K, Hausken T, Morken MH, et al. Persisting symptoms and duodenal inflammation related to Giardia duodenalis infection. J Infect 2007; 55:524.
  41. Hanevik K, Mørch K, Eide GE, et al. Effects of albendazole/metronidazole or tetracycline/folate treatments on persisting symptoms after Giardia infection: a randomized open clinical trial. Scand J Infect Dis 2008; 40:517.
  42. Argüello-García R, Cruz-Soto M, Romero-Montoya L, Ortega-Pierres G. Variability and variation in drug susceptibility among Giardia duodenalis isolates and clones exposed to 5-nitroimidazoles and benzimidazoles in vitro. J Antimicrob Chemother 2004; 54:711.
  43. Minenoa T, Avery MA. Giardiasis: recent progress in chemotherapy and drug development. Curr Pharm Des 2003; 9:841.
  44. Dunn LA, Andrews KT, McCarthy JS, et al. The activity of protease inhibitors against Giardia duodenalis and metronidazole-resistant Trichomonas vaginalis. Int J Antimicrob Agents 2007; 29:98.
  45. Abboud P, Lemée V, Gargala G, et al. Successful treatment of metronidazole- and albendazole-resistant giardiasis with nitazoxanide in a patient with acquired immunodeficiency syndrome. Clin Infect Dis 2001; 32:1792.
  46. Gascón J, Abós R, Valls ME, Corachán M. Mebendazole and metronidazole in giardial infections. Trans R Soc Trop Med Hyg 1990; 84:694.
  47. Murphy TV, Nelson JD. Five v ten days' therapy with furazolidone for giardiasis. Am J Dis Child 1983; 137:267.
  48. Goldin AJ, Hall A, Sarker RN, et al. Diagnosis of Giardia duodenalis infection in Bangladeshi infants: faecal antigen capture ELISA. Trans R Soc Trop Med Hyg 1993; 87:428.
  49. Cacopardo B, Patamia I, Bonaccorso V, et al. [Synergic effect of albendazole plus metronidazole association in the treatment of metronidazole-resistant giardiasis]. Clin Ter 1995; 146:761.
  50. Mørch K, Hanevik K, Robertson LJ, et al. Treatment-ladder and genetic characterisation of parasites in refractory giardiasis after an outbreak in Norway. J Infect 2008; 56:268.
  51. Nash TE, Ohl CA, Thomas E, et al. Treatment of patients with refractory giardiasis. Clin Infect Dis 2001; 33:22.
  52. 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.
  53. Ongerth JE, Johnson RL, Macdonald SC, et al. Back-country water treatment to prevent giardiasis. Am J Public Health 1989; 79:1633.
  54. Nayak N, Ganguly NK, Walia BN, et al. Specific secretory IgA in the milk of Giardia lamblia-infected and uninfected women. J Infect Dis 1987; 155:724.
  55. Mahmud MA, Chappell CL, Hossain MM, et al. Impact of breast-feeding on Giardia lamblia infections in Bilbeis, Egypt. Am J Trop Med Hyg 2001; 65:257.
  56. Lima AA, Soares AM, Lima NL, et al. Effects of vitamin A supplementation on intestinal barrier function, growth, total parasitic, and specific Giardia spp infections in Brazilian children: a prospective randomized, double-blind, placebo-controlled trial. J Pediatr Gastroenterol Nutr 2010; 50:309.