Flagellate protozoan – lives in duodenum or jejunum.
Faecal-oral/ from pets or birds
(humans are main reservoir of infection)
Typically from drinking water contaminated with giardia cysts (killed by boiling but NOT chlorination)
Prevalence approx. 20-30% in developing countries
Also significant numbers of cases seen in USA
Trophozoite parasite multiplies in upper bowel by binary fission – large areas of mucosa may be colonized in heavy infection
- Disrupts brush-border and affects enzyme activity.
- Stimulates inflammatory cytokine response, secretion of fluid and electrolytes and cell damage.
Trophozoites encyst as then pass through the intestine and become infective.
Most infections are asymptomatic. Aphase lasts 2 – 4 weeks.
Symptoms are worse in immunodeficiency.
- (Sometimes Explosive) watery diarrhea (NON-bloody)
- mild abdominal pain
- bloating and nausea
- low grade fever
- Chronic diarrhoea with HIV
- Lactose intoloerance
- Weight loss
- Chronic inflammation can lead to increased risk of cancer
- Stool antigen
- Culture of blood/ urine/stool/bone marrow/duodenal aspirates
- Microscopy of stool for cysts and trophozoites.
Metronidazole or tinidazole
Good personal hygiene
Access to clean water.