2. History and Distribution
• The flagellate was first observed by Dutch scientist
Antonie van Leeuwenhoek in his stools
• Named Giardia after Professor Giard of Paris and
lamblia after Professor Lamble of Prague
• Most common protozoan pathogen
• Endemicity is high in areas with low sanitation
• Develop traveler’s diarrhea
3. Habitat
• G.lamblia lives in duodenum and upper jejunum
• Only parasite found in lumen of human small intestine
5. Trophozoite
• Heart shaped or pyriform shaped
• It measures 15-9 micrometers wide and 4 micrometer thick
• Dorsally –convex
• Ventrally – it has concave sucking disk
• Sucking disk help in attachment to the intestinal mucosa
6. • Bilaterally symmetrical and possesses:
• One pair of nuclei
• 4 pairs of flagella
• Blepharoplast
• One pair of axostyles
• 2 sausage shaped parabasal or median bodies
• Motile with slow oscillation about its long axis-falling leaf
7.
8. Cyst
Infective form of the parasite
• Small and oval , surrounded by a hyaline wall
• Internal structure include 2 pairs of nuclei grouped at one end
• Axostyle form dividing line within cyst wall
• Remnants of flagella and the sucking disc seen in young cyst
12. MODE OF TRANSMISSION
• Acquires infection by ingestion of cysts in contaminated water and &food
• Ingestion of 10 cysts sufficient to cause infection in man
• Direct person to person transmission occur in children , male homosexuals &
mentally ill persons
• Enhanced susceptibility with:
• Blood group A
• achlorhydria
13. • Use of cannabis
• Chronic pancreatitis
• Malnutrition
• Immune defects like 19A deficiency & hypogammaglobulinemia
Within half an hour of ingestion,
Cysts hatches out. 2 trophozoites multiply
By binary fission colonize in duodenum
14. • Trophozoites live in the duodenum & upper jejunum, feeding by pinocytosis
• During unfavourable conditions, encystment occurs in colon
• Cysts passed in stools & remain viable in soil and water for several weeks
• 200000 cysts passed per gram of feces
• Infective dose is 10-100 cysts
15. Pathogenicity
• G.lamblia seen within crypts of duodenal and jejunal mucosa
• Does not invade tissues,remain adhered to intestinal epithelium by sucking disk
• Cause abnormalities of villous architecture by cell apoptosis & increased lymphatic
infiltration of lamina propria
• Variant specific surface proteins (VSSPs) of Giardia play role in virulence &
infectivity
16. Clinical features
• Often asymptomatic,some cases leads to
• Mucus diarrhea
• Fat malabsorption
• Dull epigastric pain
• Belching
• Flatulence
• Stool contain excess mucus & fat but no blood
17. • Children may develop
• Chronic diarrhea
• Malabsorption of fat , vit A ,Vit B12,folic acid, proteins and glucose
• Chronic giardiasis may be due to failure to develop IgA
• They colonise in gall bladder causing biliary colic & jaundice
• Incubation period -2 weeks
19. Stool examination
• Diagnosed by identification of cysts in formed stools & trophozoites in diarrheal
stool
On macroscopic examination,
Fecal specimen have offensive odour,pale colored,fatty & float in water
On microscopic examination,
Cysts & trophozites found by saline and iodine wet preparations
20. Enterotest (string test)
• Useful method for obtaining duodenal specimen
• A coiled thread inside a small weighted gelatin capsule is swallowed by the
patient,after attaching free end of thread in the cheek
• Capsule passes through stomach to the duodenum
• Capsule withdrawn after 2 hrs, placed in saline and mechanically shaken
• Centrifuged deposit of saline examined
24. TREATMENT
• METRONIDAZOLE-250mg, thrice daily for 5-7 days
• TINIDAZOLE-2 g single dose
• FURAZOLIDONE & NITAZOXANIDE preferred in children
• PAROMOMYCIN,oral aminoglycoside in pregnant females
25. PROPHYLAXIS
• Proper disposal of waste water and feces
• Practice of personal hygiene like hand washing
• Prevention of food & water contamination- boiling of water&filtration by
membrane filters
