Giardiasis is a relatively common cause of diarrhoea in the returned traveller. The usual source for this parasite is contaminated fresh water.
Giardia lamblia, a protozoon.
Common symptoms include:
Diagnosis is based on the confirmation of Giardia lamblia cysts in the stool, seen under spun stool sample microscopy.
Occasionally, the diagnosis may be made histologically as the combination of symptoms may lead to an upper GI endoscopy.
Metronidazole is the recommended treatment for this disease if symptomatic. Treatment regimes differ, however 2g daily for 3 days in divided doses appears to be quite effective. Tinidazole in a dose of 2g stat PO appears to be the treatment with the best evidence 
Post exposure prophylaxis
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