How is giardiasis treated?

Updated: Oct 01, 2018
  • Author: Hisham Nazer, MBBCh, FRCP, DTM&H; Chief Editor: Burt Cagir, MD, FACS  more...
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Standard treatment for giardiasis consists of antibiotic therapy. [62]  Metronidazole is the most commonly prescribed antibiotic for this condition. [35, 63, 64]  However, metronidazole use has been associated with significant failure rates in clearing parasites from the gut and with poor patient compliance. [65]  In addition, an increasing incidence of nitroimidazole-refractory giardiasis has been reported, particularly in travelers from India [66]  and other regions in Asia. [67]  An optimal treatment strategy for refractory giardiasis remains to be determined, and no standard treatment regimen for nitroimidazole-refractory giardiasis exists yet. [67]

In a systematic review and meta-analysis of 7 trials comprising 639 patients to evaluate the efficacy of mebendazole in children with giardiasis, investigators found no clinical difference in parasitologic cure between mebendazole and metronidazole, with a relative risk of 0.81 but high heterogeneity. [7] The researchers indicated clinicians should use caution in interpreting and using these results in clinical practice

Real-time polymerase chain reaction (PCR) may aid in the evaluation of treatment success. van den Bijllaardt et al showed it took about 1 week for samples to become negative after treatment of a G lamblia infection, indicating rapid clearance of the parasitic DNA following successful therapy. [68]

Appropriate fluid and electrolyte management is critical, particularly in patients with large-volume diarrheal losses. [9]

Treat children with acute or chronic diarrhea who manifest a failure to thrive, malabsorption, or other GI tract symptoms in whom Giardia organisms have been identified. [60]

Generally, do not treat asymptomatic persons who excrete the organism, except to prevent household transmission (eg, from toddlers to pregnant women or to patients with hypogammaglobulinemia or cystic fibrosis) and to permit adequate treatment in individuals with possible Giardia intestinalis –associated antibiotic malabsorption who require oral antibiotic treatment for other infections. [39, 69]

Routine treatment of infected persons in highly endemic areas where water supplies continue to be contaminated is of questionable value because reinfection may readily occur. [18, 70] Treat all infected persons who are in nonendemic areas. [71]

Ensure that close contacts of the patient are also examined for giardiasis and treated if infected.

Severely dehydrated or malnourished patients should be admitted for further care.

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