Giardiasis is the intestinal infection resulting from infestation with the
human parasite Giardia intestinalis, also called Giardia lamblia, The infec
tion may be asymptomatic or present with a variety of symptoms such as diar
rhoea. weight loss, abdominal cramps, and failure to thrive, Giardiasis is
most often diagnosed after recent travel or in day care centres. The organi
sm has two stages in its life cycle. It is usually ingested as a cyst with
as few as 10-25 cysts being sufficient to cause infection. After excystatio
n, the organism is a replicative trophozoite which may attach to the small
bowel wall. Giardia intestinalis does not invade the bowel wall, Trophozoit
es may encyst and be shed in faeces for future ingestion by another host. D
iagnosis of infection is by stool examination which may also eliminate othe
r possible infectious agents. Small bowel biopsy may be necessary in diffic
ult individual cases or to rule out noninfectious illnesses, and stool ELIS
A may serve for large population screening examinations. The mainstay of tr
eatment is metronidazole 250-400 mg three times per day by mouth for 5 days
.