Article Figures & Data
Figures
- Fig. 1.
Ventral surface of a Giardia lambliatrophozoite imaged by scanning electron microscopy. It demonstrates the disk and flagella. A second trophozoite is seen behind it. Magnification, ×8,100. Photo courtesy of David Dorward, Rocky Mountain Laboratory, National Institutes of Health, Hamilton, Mont.
- Fig. 2.
Outline of the diagnosis and management of suspected cases of giardiasis.
Tables
- Table 1.
Efficacy of anti-Giardia drugs in adult and pediatric infectiona
Drug Doseb Median efficacy (%)c Efficacy range (%) Metronidazole 500–750 mg/day × 5–10 days 88 60–95 2.0–2.4 g, single dose 48 36–60 2.0–2.4 g, q.d. × 2 days 71 67–80 2.0–2.4 g, q.d. × 3 days 93–100 15–22.5 mg/kg/day × 5–10 daysd 94 80–100 Tinidazole 300 mg/day × 7 days 87 74–100 1.0–2.0 g, single dose 92 86–100 50 mg/kg, single dosed 91 80–96 Ornidazole 1.0–2.0 g, single dose 96–100 40–50 mg/kg, single dosed 92–100 Secnidazole 2.0 g, single dose 86–100 30 mg/kg, 1 or 2 dosesd 88–100 Quinacrine 300 mg/day × 5–7 days 95–100 6–8 mg/kg/day × 5–10 daysd 92–95 Furazolidone 400 mg/day × 7–10 days 80–85 8 mg/kg/day × 7–10 daysd 92 81–96 Albendazole 200–800 mg/day × 1–3 days 24–81 200–400 mg/day × 5–7 days 94–100 Paromomycin 10–50 mg/kg/day or 1,500 mg/day × 5–10 days 55–88 Bacitracin zinc 240,000 U/day × 10 days 95 ↵a Efficacy is based on studies that may vary in design, entry methodology, or outcome measure. When separate pediatric populations were studied, they are designated. See the text for references.
↵b Doses are total daily amounts, which may or may not have been given in divided doses. Actual treatment recommendations are presented in Table 2. q.d., once a day.
↵c Median efficacy is given when the results of four or more studies are included.
↵d Pediatric population only.
- Table 2.
Recommended dosing and adverse effects of anti-Giardia drugs
Drug Adult dosef Pediatric dose Adverse effects Metronidazolea 250 mg t.i.d. × 5–7 days 5 mg/kg t.i.d. × 5–7 days Headache, vertigo, nausea, metallic taste, urticaria Disulfiram-like reaction with alcohol ingestion Rare: pancreatitis, central nervous system toxicity, reversible neutropenia, peripheral neutropathy, T-wave flattening with prolonged use Mutagenic/carcinogenic? Tinidazoleb 2 g, single dose 50 mg/kg, single dose (max, 2 g) As for metronidazole Ornidazolec 2 g, single dose 40–50 mg/kg, single dose (max, 2 g) As for metronidazole Quinacrinec 100 mg t.i.d. × 5–7 days 2 mg/kg t.i.d. × 7 days Nausea and vomiting, dizziness, headache Yellow/orange discoloration of skin and mucous membranes Rare: toxic psychosis Furazolidoned 100 mg q.i.d. × 7–10 days 2 mg/kg q.i.d. × 10 days Nausea, vomiting, diarrhea Brown discoloration of urine; disulfiram-like reaction with alcohol ingestion Reacts unfavorably with MAO inhibitors Mild hemolysis in G6PDH deficiency Carcinogenic? Paromomycina 500 mg t.i.d. × 5–10 days 30 mg/kg/day in 3 doses × 5–10 days Ototoxicity and nephrotoxicity with systemic administration Albendazolea 400 mg q.d. × 5 days 15 mg/kg/day × 5–7 days (max, 400 mg) Anorexia, constipation Rare: reversible neutropenia and elevated liver function tests Teratogenic? Bacitracin zince 120,000 U b.i.d. × 10 days Not tested in children under 10 yr Nausea, vomiting, abdominal discomfort Nephrotoxicity with systemic absorption ↵a Not a U.S. Food and Drug Administration-approved indication.
↵b Not available in the United States.
↵c No longer produced in the United States. May be obtained from Panorama Pharmacy, Panorama City, Calif.
↵d Available in a liquid formulation.
↵e Not a U.S. Food and Drug Administration-approved indication. Information is based on only one study 14.
↵f q.d., once a day; b.i.d., twice a day; t.i.d., three times a day; q.i.d., four times a day.
- Table 3.
Recommendations for therapy of giardiasis
Clinical scenario Drug and duration of treatmenta Symptomatic infection, USA Adult and pediatric Metronidazole for 5–7 days Alternatives Furazolidone for 7–10 days or quinacrine for 5–7 days or albendazole for 5–7 days Symptomatic infection, overseas Adult and pediatric Tinidazole (single dose) or ornidazole (single dose) Pregnancy First trimester Paromomycin for 5–10 days Second and third trimesters Paromomycin for 5–10 days or metronidazole for 5–7 days Resistant infection or relapse Drug of different class or combination nitroimidazole plus quinacrine for 2 wk or more ↵a For drug dosing, see Table 2.
