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Giardiasis: An Overview

[ Vol. 13 , Issue. 2 ]


Alexander K.C. Leung*, Amy A.M. Leung, Alex H.C. Wong, Consolato M. Sergi and Joseph K.M. Kam   Pages 134 - 143 ( 10 )


Background: Giardiasis is an important cause of waterborne and foodborne diarrhea, daycare center outbreaks, and traveler's diarrhea.

Objective: The study aimed to provide an update on the evaluation, diagnosis, and treatment of giardiasis.

Methods: A PubMed search was completed in Clinical Queries using the key terms “giardiasis”, "Giardia lamblia", "Giardia duodenalis" and "Giardia intestinalis". The search strategy included metaanalyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to the English literature. Patents were searched using the key term “giardiasis” from

Results: Giardiasis is caused by the protozoan parasite Giardia lamblia. The parasite is transmitted by the fecal-oral route, frequently through ingestion of contaminated water and food or person-to person transmission. Risk factors for infection include children in day-care settings, child-care workers, institutionalized individuals, travelers in endemic areas, ingestion of contaminated or recreational water, immunodeficiency, cystic fibrosis, and oral-anal sex. Approximately 50 to 75% of infected children are asymptomatic. Other children present acute or chronic diarrhea. Direct fluorescent antibody tests that detect intact organisms, enzyme immunoassays that detect soluble antigens, and multiplex real-time polymerase chain reaction assays that detect specific genes of the parasite in stool samples have improved sensitivity and specificity compared with microscopic examination of stool specimens for the detection of Giardia trophozoites or cysts. Drugs used in the treatment of symptomatic giardiasis are reviewed in this study. Moreover, recent patents related to the management of giardiasis are also discussed.

Conclusion: Metronidazole, tinidazole, and nitazoxanide are drugs of choice. Resistance to common antigiardial drugs has increased in recent years, therefore, the search for new molecular targets for antigiardial drugs is urgently needed. In general, treatment of asymptomatic carriers is not recommended. Purification of water supply is an important preventive measure.


Antigiardial drugs, diarrhea, foodborne, Giardia duodenalis, Giardia intestinalis, Giardia lamblia, parasites, waterborne.


Department of Pediatrics, The University of Calgary, Alberta Children’s Hospital, Calgary, Alberta, Department of Family Medicine, The University of Alberta, Edmonton, Alberta, Department of Family Medicine, The University of Calgary, Calgary, Alberta, Departments of Pediatrics, Laboratory Medicine, and Pathology, The University of Alberta, Edmonton, Alberta, Stanley Ho Centre for Emerging Infectious Diseases, Jockey Club School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Shatin

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