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PARASITEOLOGY :Giardia lamblia
The document presents a case study of a child diagnosed with giardiasis, characterized by symptoms like nausea, anorexia, and diarrhea, accompanied by stool examination results. It elaborates on the morphology, life cycle, pathogenesis, clinical features, and laboratory diagnosis of Giardia lamblia, noting various treatment options and preventive measures. The document emphasizes that proper hygiene and water sanitation are crucial in managing and preventing infections.
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PARASITEOLOGY :Giardia lamblia
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- 2. – A childwith nausea, anorexia, and explosive, watery diarrhea was seen by a physician who ordered an O & P (ova and parasites) stool examination. Below are images from a wet mount preparation stained with Lugol's iodine (Figure A) and from a trichrome stained smear of the child's stool specimen (Figures B, C, and D). The average size of the objects in the images was 13 µm in length and 8 µm in width. A B C D
- 3. GIARDIA LAMBLIA Abhishek. B. K 3rdyear medical student at Government medical college Palakkad
- 4. Facts – Other names:Lamblia intestinalis, Giardia duodenalis – If the organism is split and stained, resembles the "smiley face" symbol. – "beaver fever"
- 5. What we aregoing to learn – History – General features – Distribution – Habitat – Morphology – Life cycle – Pathogenesis – Clinical features – Lab diagnosis – Treatment – Prophylaxis
- 6. History A Giardia trophozoite, drawn byVilém Lambl and published in 1859.
- 7. General features – Parasiticprotozoa – Whip-like flagella for locomotion (flagellates) – Lumen dwelling flagellates – Pathogenic – Anaerobes
- 8. Distribution – Cosmopolitan – Sporadicindividual infections / epidemic form (drinking water) – Endemicity very high in: low sanitation . tropics and subtropics – Visitors to such places : traveler’s diarrhea
- 9. Habitat – Duodenum – Upperjejunum – Only protozoan parasite found in lumen of human small intestine
- 10. Morphology – Two forms 1.Trophozoite (vegetative form) 2. Cyst (cystic form )
- 11. Trophozoite (vegetative form) –Shape : tennis racket ( heart shaped or pyriform shaped ) – Rounded anteriorly and pointed posteriorly – Dorsally convex ; ventrally concave sucking disc – Bilaterally symmetrical and has – 1 pair nuclei, 4 pair flagella, 4 pair blepharoplast, 1 pair of axostyle, 2 sausage- shaped parabasal or median bodies – Motile- slow oscillation in long axis-falling leaf BB N AD MB A PF
- 12. Cyst (cystic form) – Infective form – Cyst : small, round – surrounded by hyaline cyst wall – 2 pair nuclei grouped at one end – Young cyst one pair of nuclei – Axostyle –diagonally – Remnants of flagella and sucking disc – young cyst
- 13. Life cycle – Onehost – Infective form cyst – Mode of transmission : ingestion of cyst in contaminated water and food – Infective dose : 10-100 – Children commonly affected – Direct person to person transmission may also occur – Enhanced susceptibility: blood group A . Achlorhydria . Use of cannabis . Chronic pancreatitis . Immune deficiency (19 A deficiency ) . Hypogammaglobulinemia
- 14. – 10 cysts– can cause infection – 2,00,000 cyst/feces Within half hour of ingestion :Cyst hatches out into trophozoites Multiply by binary fission and colonize duodenum Live in upper part of jejunum Unfavorable condition – encystment in colon Feeding – pinocytosis Cysts passed in stool – remain in soil for weeks This Photo by Unknown Author is licensed under CC BY-SA
- 15. Pathogenesis – Site :duodenal mucosa and jejunal mucosa – It does not invade the tissue ; remain adherent to intestinal epithelium – Cause : abnormal villous architecture – apoptosis . Increased lymphatic infiltration of lamina propria . Loss of brush border epithelium-enzyme deficiency* – Variant specific surface protein (vssp) – Antigenic variation- evasion of host immune system
- 16. Clinical features – Asymptomatic –Mucus diarrhea with no blood – Steatorrhea – Dull epigastric pain – Belching and flatulence – Children : chronic diarrhea . Malabsorption . Weight loss and spur like syndrome – Occasionally colonize gall bladder –biliary cholic and Jaundice – Incubation period 2 weeks
- 17. Clinical types Acute giardiasis –It is characterized by acute watery diarrhea, abdominal cramp, bloating and flatulence. Occasionally nausea, vomiting, fever, rashes or constipation in some. – Pus, blood and mucus are not seen in stool. – The condition lasts for 5-7 days. Chronic giardiasis – Symptoms includes chronic diarrhea with malabsorption of fat (steatorrhea) and malabsorption of vitamin A, protein and D-xylose, weight loss, malaise, nausea, anorexia – Protuberance of abdomen, spindly extremities and stunted growth are most common sign in children. – It lasts for several weeks
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- 19. Stool examination – Macroscopicexamination : pale colored, offensive odor, fatty and float in water – Microscopic examination : cysts and trophozoites in diarrheal stool by saline and iodine wet preparations – Concentration techniques : formal ether or zinc acetate – Asymptomatic carriers' cysts seen
- 20. Enterotest ( stringtest ) – A string test involves swallowing a string with a weighted gelatin capsule, to obtain a sample from the upper part of the small intestine. – The capsule is swallowed and one end of the string is taped to the side of the patient’s face – Following a period of approximately 4 hr, the string and any adsorbed gastrointestinal fluid is withdrawn through the mouth. – Any bile, blood, or mucus attached to the string is examined under the microscope as a wet preparation for the presence of intestinal parasites (organisms/eggs).
- 21. Serodiagnosis Antigen detection – ELISA –Immunochromatographic strip test – Indirect immunofluorescence Indicate active infection ProSpect T/Giardia kit : GSA65 Sensitivity 95% Specificity 100% Antibody detection – ELISA – Indirect immunofluorescence Epidemiological and pathophysiological study Cannot differentiate present / past infection Low Sensitivity and Specificity
- 22. Molecular methods – DNAprobes – PCR – To demonstrate parasitic genome in stool sample
- 23. Treatment – Metronidazole -250mg tid for 5-7 days – Tinidazole -2g single dose – Tinidazole > Metronidazole – Furazolidone -100 mg qid for 7 days / Nitazoxanide – 500 mg bid (for children) – Paromomycin oral aminoglycoside 500 mg tid for 5 days (pregnant lady ) – *only give treatment for symptomatic cases
- 24. Prophylaxis – Proper disposalof waste water and feces – Practice of personal hygiene – Prevention of food and water contamination – Identifying the source of infection, particularly in outbreak situation – Health education at individual as well as community levels
- 25. Summary – Parasitic Lumendwelling flagellated protozoan – Mucus diarrhea with no blood – Stool examination : pale colored, offensive odor, fatty and float in water ; cysts and trophozoites seen microscopy – Serologically : ELISA ,Immunochromatographic strip test ,Indirect immunofluorescence – Treatment :Tinidazole > Metronidazole ,Furazolidone (for children) Paromomycin – Prophylaxis: hygiene
- 26. Reference – https://www.cdc.gov/dpdx/monthlyCaseStudies/2002/case76.h tml – https://en.wikipedia.org/wiki/Giardia_lamblia –Paniker’s textbook of medical parasitology – https://www.onlinebiologynotes.com/giardia-lamblia- morphology-life-cycle-pathogenesis-clinical-manifestation-lab- diagnosis-and-treatment/
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Editor's Notes
- #16 Disaccharides