Giardiasis symptoms vary from asymptomatic passage of cysts to acute self-limiting diarrhea or chronic diarrhea. Association with growth restriction in children has been well described.
Diagnosis is by detection of cysts or trophozoites in a stool sample.
Tinidazole or metronidazole 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 and immunocompromised hosts may present with weight loss and failure to thrive due to malabsorption.
History and exam
Key diagnostic factors
- frequent belching
Other diagnostic factors
- abdominal bloating and discomfort
- weight loss
- nausea and vomiting
- contaminated water/food
- domestic animals living in or around the house
- young age
- male sex
- day-care center attendance
- men having sex with men
- recent antibiotic use
1st investigations to order
- direct fluorescence antibody (DFA) test or enzyme-linked immunosorbent assay
- nucleic acid amplification test, polymerase chain reaction of stool sample
- stool microscopy
Investigations to consider
- Lateral flow immunoassay (e.g., ImmunoCard STAT!)
- string test (EnteroTest)
- duodenal aspirates and biopsies
nonpregnant adult or child
pregnant; first trimester
pregnant; second or third trimester
treatment failure or resistance
- Rotavirus gastroenteritis
- Functional diarrhea
- Celiac disease
- CDC yellow book: chapter 4 - travel-related infectious diseases: giardiasis
- Practical guidance for clinical microbiology laboratories: laboratory diagnosis of parasites from the gastrointestinal tract
Diarrhea in adultsMore Patient leaflets
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