Giardia lamblia is a protozoan parasite that infects the small intestine. It exists in two forms - a trophozoite, which is the vegetative form, and a cyst, which is the infective form. The cyst is passed in feces and can remain viable in soil and water for weeks. Infection occurs when cysts are ingested through contaminated food or water. In the small intestine, cysts hatch into trophozoites which colonize the duodenum and jejunum. Symptoms include diarrhea, abdominal pain, and malabsorption. Diagnosis is made by identifying cysts or trophozoites in stool samples or small intestine samples. Treatment involves antibiotics like metronidaz

1. GIARDIA LAMBLIA

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

4. MORPHOLOGY
It exists in 2 forms:
• Trophozoite (vegetative form)
• Cyst (cystic form)

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

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

10. Life cycle
• Giardia passes life cycle in 1 host
INFECTIVE FORM
Mature 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

18. Lab diagnosis

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

21. Serodiagnosis
• Antigen detection:
ELISA
Immunochromatographic strip test
Indirect immunofluorescence
• ELISA kits –ProSpecT detects Giardia specific antigen 65
• Sensitivity 95 % and specificity 100%
• Used for quantification of cysts

22. • Antibody detection
ELISA & Indirect immunofluorescence test
• Cannot differentiate between recent & past infection
• Lack specificity & specificity

23. Molecular method
• DNA probe
• PCR

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