Comparative Clinical Trial of Mebendazole, Praziquantel and Metronidazole in Treatment of Human Giardiasis


1 Department of Infectious Diseases, Shahrekord University of Medical Sciences, Shahrekord, Iran

2 Department of Pediatrics, Shahrekord University of Medical Sciences, Shahrekord, Iran

3 Department of Parasitology, Shahrekord University of Medical Sciences, Shahrekord, Iran

4 Department of Epidemiology, Shahrekord University of Medical Sciences, Shahrekord, Iran


Background: Giardia lamblia is a common intestinal parasite associated with social or personal problems. Giardiasis is distributed all over the world; however, the infection is more prevalent in developing countries. Metronidazole is now considered as a drug of choice for giardiasis treatment. The increasing number of reports of refractory cases as well as side effects of this drug resulted in establishment of more investigation for new compounds.

Methods: In a randomized clinical trial, 90 Giardia lambilia infected cases, aged 2-30 years and each proven to be infected with Giardia lambilia by the microscopical examination of fecal sample, were randomly allocated to 3 groups. Group 1 was given metronidazole with three daily 20 mg/kg doses for 7 days. Group 2 and 3 were seperately given mebendazole and praziquantel, with single 60 mg/kg and 20 mg/kg doses, respectively, and Parasitological cure was documented when stool examination for Giardia lambilia was negative for 3 times within 7–10 days after therapy.

Results: Seventeen of 30 patients treated with praziquantel, 15 of 30 patients (50%) treated with mebendazole and 28 of 30 individuals (93%) treated with metronidazole had negative stool examination results. There was not a significant difference between cure rates of praziquantel and mebendazole (P>0.05), while this difference between these two drugs and metronidazole was significant (P<0.05).

Conclusion: Mebendazole and praziquantel were not as effective as metronidazole in the treatment of Giardiasis.


1. Sayyari A, Imanzadeh F, Bagheri Yazdi S, Karami H, Yaghoobi M. Prevalence of intestinal parasitic infections in the Islamic Republic of Iran. East Mediterr Health J. 2005;11(3).
2. Heidari A, Rokni M. Prevalence of intestinal parasites among children in day-care centers in Damghan-Iran. Iranian J Publ Health. 2003;32(1):31-4.
3. Daryani A, Ettehad G, Sharif M, Ghorbani L, Ziaei H. Prevalence of intestinal parasites in vegetables consumed in Ardabil. 2008.
4. Haque R, Roy S, Kabir M, Stroup S, Mondal D, Houpt E. Giardia assemblage A infection and diarrhea in Bangladesh. The Journal of infectious diseases. 2005;192(12):2171.
5. Lora-Suarez F, Marin-Vasquez C, Loango N, Gallego M, Torres E, Gonzalez M, et al. Giardiasis in children living in post-earthquake camps from Armenia(Colombia). BMC Public Health. 2002;2(1):5.
6. Awasthi S, Pande V. Prevalence of malnutrition and intestinal parasites in preschool slum children in Lucknow. Indian pediatrics. 1997;34:599-606.
7. Sullivan P, Marsh M, Phillips M, Dewit O, Neale G, Cevallos A, et al. Prevalence and treatment of giardiasis in chronic diarrhoea and malnutrition. British Medical Journal. 1991;66(3):304.
8. Burke JA. The clinical and laboratory diagnosis of giardiasis. Critical Reviews in Clinical Laboratory Sciences 1977;7(4):373-91.
9. Sahagun J, Clavel A, Goni P, Seral C, Llorente M, Castillo F, et al. Correlation between the presence of symptoms and the Giardia duodenalis genotype. European Journal of Clinical Microbiology & Infectious Diseases. 2008;27(1):81-3.
10. Dutta A, Phadke M, Bagade A, Joshi V, Gazder A, Biswas T, et al. A randomised multicentre study to compare the safety and efficacy of albendazole and metronidazole in the treatment of giardiasis in children. Indian journal of pediatrics. 1994;61(6):689-93.
11. Levi G, de Avila C, Neto V. Efficacy of various drugs for treatment of giardiasis: A comparative study. The American Journal of Tropical Medicine and Hygiene. 1977;26(3):564.
12. Craft J, Murphy T, Nelson J. Furazolidone and quinacrine: comparative study of therapy for giardiasis in children. Archives of Pediatrics and Adolescent Medicine. 1981;135(2):164.
13. Barutzki D, Schimmel A, Schaper R, Efficacy of pyrantel embonate fapaGsinid. Am J Vet Res.59:1134-6.
14. Escobedo A, Cañete R, Gonzalez M, Pareja A, Cimerman S, Almirall PA. randomized trial comparing mebendazole and secnidazole for the treatment of giardiasis. Annals of tropical medicine and parasitology. 2003;97(5):499-504.
15. Lappin MR. editor Giardia infections 2006.
16.Sadjjadi S, Alborzi A, Mostovfi H. Comparative clinical trial of mebendazole and metronidazole in giardiasis of children. Journal of tropical pediatrics. 2001;47(3):176.
17. Cañete R, Escobedo AA, Elena González M, Almirall P, Cantelar N. 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. Current Medical Research and Opinion®. 2006;22(11):2131-6.
18. Pengsaa K, Limkittikul K, Pojjaroen-anant C, Lapphra K, Sirivichayakul C, Wisetsing P, et al. Single-dose therapy for giardiasis in school-age children. 2002.