Giardiasis infection may be asymptomatic, or can cause diarrhoea
(sometimes severe), weight loss, malabsorption, and, in children,
failure to thrive. It is usually treated with metronidazole given three
times daily for five to 10 days.
To evaluate the relative effectiveness of alternative antibiotic
regimens for treating adults or children with symptomatic giardiasis.
We searched the Cochrane Infectious Disease Group Specialized Register,
the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 6
2012); MEDLINE, EMBASE, LILACS and the International Clinical Trials
Registry Platform Search Portal (3 July 2012).
We included randomized controlled trials (RCT) comparing metronidazole
administered for five to 10 days with any of the following drugs:
metronidazole (single dose), tinidazole, albendazole, mebendazole, and
nitazoxanide. The primary outcomes were parasitological and clinical
Data collection and analysis
Two authors independently assessed studies for inclusion, performed the
risk of bias assessment, and extracted data. We summarized data using
risk ratios and mean differences and we presented the results in forest
plots and performed meta-analyses where possible. We assessed
heterogeneity using the Chi2 test, I2 statistic and visual inspection;
and we explored this by using subgroup analyses.We assessed the quality
of evidence by using the GRADE approach.
We included 19 trials, involving 1817 participants, of which 1441 were
children. Studies were generally small, with poor methods reporting.
Most reported parasitological outcomes rather than clinical improvement.
Ten trials, from India, Mexico, Peru, Iran, Cuba, and Turkey, compared
albendazole (400 mg once daily for five to 10 days) with metronidazole
(250 mg to 500 mg three times daily for five to 10 days). This
once-daily regimen of albendazole is probably equivalent to
metronidazole at achieving parasitological cure (RR 0.99, 95% CI 0.95 to
1.03; 932 participants, 10 trials; moderate quality evidence), and
improving symptoms (RR 0.98, 95% confidence interval (CI) 0.93 to 1.04;
483 participants, five trials; moderate quality evidence), but the
duration of follow-up was short (two to three weeks). Albendazole
probably has fewer side effects than metronidazole (gastrointestinal
side effects: RR 0.29, 95% CI 0.13 to 0.63; 717 participants, eight
trials; moderate quality evidence; neurological side effects: RR 0.34,
95% CI 0.18 to 0.64; 453 participants, five trials; low quality
Five trials from Turkey, Spain and the UK compared mebendazole (200 mg
three times daily for five to 10 days) with metronidazole (5 mg/kg (or
250 mg) three times daily for five to 10 days). These trials were small
in size, and at high risk of bias. Consequently, reliable conclusions on
the relative effectiveness cannot be made (very low quality evidence).
Five further trials, from Iran, Spain and Peru, have evaluated shortened
regimens of tinidazole (single dose; 179 participants, three trials),
metronidazole (single dose; 55 participants, one trial), and
nitazoxanide (three days; 55 participants, one trial). Again, these
trials were at high risk of bias and too small to reliably detect or
exclude important differences (very low quality evidence).
Albendazole may be of similar effectiveness to metronidazole, may have
fewer side effects, and has the advantage of a simplified regimen.
Large, high quality trials, assessing clinical outcomes (such as
diarrhoea) will help assess further alternatives.
Plain Language Summary: Drugs for treating giardiasis
Giardiasis is an infection of the small intestine caused by a
microscopic organism called Giardia lamblia. The infection is passed
from person to person by ingesting faecally contaminated water or food.
Symptoms frequently include diarrhoea, abdominal pain, flatulence,
bloating, vomiting, and weight loss. In this review, we assess
alternatives to the most commonly used treatment for giardiasis;
metronidazole given orally for five or more days.
We identified 19 trials involving 1817 participants, of which 1441 were
children. Most trials had a small number of participants and were at
high risk of bias. Albendazole is probably of similar effectiveness to
metronidazole, probably has fewer side effects, and has the advantage of
a simplified regimen. Large, high quality trials, assessing clinical
outcomes are required to assess further alternatives.
Granados, C.E.; Reveiz, L.; Uribe, L.G.; Criollo, C.P. Drugs for treating giardiasis. Cochrane Database of Systematic Reviews (2012) (Issue 12) Art. No.: CD007787. [DOI: 10.1002/14651858.CD007787.pub2]
Drugs for treating giardiasis.