Giardiasis microbiology

1. GIARDIASIS

2. INTRODUCTION
CAUSATIVE AGENT – Giardia lamblia [ also known as G . Intestinalis or G . Duodenalis ]

3. MORPHOLOGY
• Giardia inhabits in crypts of duodenum and upper part of jejunum in man
• Two forms:
• 1. pear shaped trophozoite : pathogenic form and feeding stage of parasite
• 2. tetra nucleated oval cysts : infective form as well as the diagnostic form of parasite

4. LIFE CYCLE

5. PATHOGENICITY
• Infective dose : 10 – 25 cysts
• Risk factors : children more commonly effected
• Other high risk group : elderly debilitated persons , poor hygiene and immune deficient individuals
• Pathogenic form : trophozoites , pathogenic form adhere to duodenal mucosa ,cause disruption of
intestinal epithelium , leads to increased permeability and malabsorption

6. • Malabsorption of fat :leads to foul smelling profuse frothy diarrhea
• Disaccharidase deficiency :leading to lactose intolerance
• Malabsorption of vitamin A , B12 and iron
• Protein loosing enteropathy

7. • Antigenic variation : Giardia undergoes frequent antigenic variation due to a cysteine rich protein on its
surface called variant surface protein [VSP].

8. CLINICAL FEATURES
• 3 Stages:
• 1. Asymptomatic carriers : most infected persons are asymptomatic , harbor the cysts in the gut and
spread the infection
• 2. Acute giardiasis
• Common symptoms include diarrhea , abdominal pain, bloating , belching ,flatus and vomiting
• Fatty diarrhea
• 3. Chronic giardiasis :
• GI symptoms : recurrent episodes of foul smelling diarrhea ,foul flatus ,sulfurous belching with rotten
egg taste, and profound weight loss leading to growth retardation

9. LABORATORY DIAGNOSIS
• STOOL EXAMINATION
• Gold standard for diagnosis ,which detects cysts and trophozoites
• Ideally 3 specimens from alternate days within 10 days should be taken
• G.intestinalis is identified in 50 to 70% of patients after a single stool examination and in more than
90% after 3 stool examination
• Pus cell or blood – alternative diagnosis
• Concentration techniques – zinc sulfate floatation or formalin ether sedimentation
• If stool examination is negative direct duodenal samples like aspirates or biopsy by endoscopy
• Should be processed
• Permanent stains – trichrome stain –demontrate cysts and trophozoites

11. ENTERO TEST [ STRING TEST ]
• Uses gelatin capsule attached to a thread containing a weight
• Capsule dissolved in stomachthread carried to duodenumgets unfoldedtakes up the duodenal
samples
• 4 hrs later thread withdrawn and shaken in saline to release trophozoites which can be detected
microscopically by wet mount or permanent stained smear

12. HISTOPATHOLOGY
• Endoscopy guided duodenal biopsy tissue
• Processed by touch preparation
• Stain – Giemsa stain

13. ANTIGEN DETECTION STAIN
• ELISA
• Direct fluorescent antibody [DFA]
• Rapid ICT
• Detect cyst wall antigens
• Highly specific and sensitive

14. ANTIBODY DETECTION
• ELISA
• IFA
• Drawback -Cannot differentiate recent and past infection

15. CULTURE
• Axenic media like Diamond’s media
• For research purpose
• To Prepare the antigens

16. MOLECULAR METHODS
• BIOFIRE FILM ARRAY
• MOLECULAR TYPING

17. RADIOLOGICAL FINDING
• FLUOROSCOPY May reveal hypermotility at the duodenal and jejunal levels
• XRAY AFTER BARIUM MEAL may reveal non specific irregular mucosal thickening with large dilated
loops of hypotonic bowel

18. TREATMENT
• TINIDAZOLE 2g once orally DOC
• Metronidazole for 5 days or Nitazoxanide for 3g given alternatively
• FurazolidoneChildren
• Auranofin, Paromomycin Pregnancy
• AIDS & Hypogammaglobulinemia prolonged therapy with metronidazole [21 days]
• Metronidazole resistance Auranofin

19. PREVENTION
• Impoved food and personal hygiene
• Boiling and filtering of potentially contaminated water
• Treatment of asymptomatic carriers
• No vaccine is currently available

20. THANK YOU