Giardia lamblia is a flagellated protozoan parasite infecting the small intestine and biliary tree
-it is endemic around the world
-risk factors: drinking contaminated water, hypochlorhydria, immunocompromise, unprotected sex, exposure to infected day care centers, camping sites, swimming areas
-After ingestion, cysts excyst in the small intestine and release flagellated trophozoites in the proximal small intestine. Both cysts and trophozoites are excreted in feces.
-Chlorination does not destroy cysts; they can be eradicated from water by either boiling or filtration
-In the United States and Europe, Giardiasis is the most common intestinal protozoan pathogen
Symptoms & Signs
-the manifestations of infection range from asymptomatic carriage (most common) to chronic diarrhea and malabsorption
Acute giardiasis: nausea, vomiting, abdominal pain, bloating, belching, flatus, diarrhea; The stool is greasy in appearance, foul-smelling, and floats. It is usually devoid of blood or mucus.
Chronic giardiasis: can be episodic or continual; diarrhea, increased flatulence, sulfurous belching, weight loss, malabsorption,vitamin deficiencies, growth retardation, dehydration; stools are foul smelling, greasy or frothy, without blood, pus or mucus.
-It can be diagnosed by detection of parasite antigens in the feces, by identification of cysts or trophozoites in the feces or by nucleic acid amplification tests
-Cysts are oval and contain four nuclei; Trophozoites are pear-shaped and contain
two nuclei and four pairs (8) of flagella; they have ventral sucking disks
Effective agents: Metronidazole, tinidazole, quinacrine, furazolidone, nitazoxanide and paromomycin
-Unlike metronidazole, tinidazole, furazolidone is safe in pregnancy