Symptoms vary from asymptomatic passage of cysts to acute self-limiting diarrhea or chronic diarrhea. A minority of infected individuals experience an abrupt onset of abdominal cramps, watery diarrhea, vomiting, foul flatus, and fever lasting 3-4 days before proceeding into a more subacute phase. Most develop gradual symptoms that become recurrent or resistant.
Diagnosis is by detection of cysts or trophozoites in a stool sample.
Metronidazole or tinidazole is recommended as first-line treatment.
Transmission is via the fecal-oral route. Personal hygiene is key to prevention.
Giardiasis is an enteric infection caused by a eukaryotic, flagellated, binucleated protozoan parasite called Giardia lamblia . First described in 1681, it is a major cause of diarrheal disease in human beings and other mammals.   Children may present with weight loss and failure to thrive due to malabsorption.
Memorial Hermann Southwest Hospital
MW declares that he has no competing interests.
Clinical Assistant Professor
Department of Internal Medicine
The University of Texas at Austin, Dell Medical School
Infectious Diseases Attending
Seton Medical Center Williamson and St David's Medical Center
FAK declares that he has no competing interests.
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