Giardiasis : An overview.

BACKGROUND: Giardiasis is an important cause of waterborne and foodborne diarrhea, day-care center outbreaks, and traveler's diarrhea.

OBJECTIVE: 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 meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. Patents were searched using the key term "giardiasis" from www.freepatentsonline.com.

RESULTS: Giardiasis is caused by the protozoan parasite Giardia lamblia. The parasite is transmitted through the fecal-oral route, frequently through ingestion of contaminated water and food or through 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 with acute or chronic diarrhea. Direct florescence 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. Recent patents related to the management of giardiasis are discussed.

CONCLUSION: Metronidazole, tinidazole, and nitazoxanide are the drugs of choice. Resistance to common antigiardial drugs has increased in recent years. As such, 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.