Tissue and Intestinal Flagellates

1. Tissue and Intestinal Flagellates Practical parasitology Dr. Ayham Abulaila

2. Flagellates: • Giardia lamblia • Dientamoeba fragilis • Chilomastix mesnili • Trichomonas hominis • Enteromonas hominis • Retortamonas intestinalis • Ameba: • Entamoeba histolytica • Entamoeba dispar • Entamoeba coli • Entamoeba hartmanni • Endolimax nana • Iodamoeba bütschlii • Apicomplexa: • Cryptosporidium hominis • Cryptosporidium parvum • Cyclospora cayetanensis • Isospora belli • Other: • Blastocystis hominis • Balantidium coli INTESTINAL PROTOZOA unicellular eukaryotic organisms

3. Giardia lamblia • worldwide distribution • higher prevalence in developing countries (20%) • 1-6% in temperate countries • most common protozoa found in stools • ~200 million clinical cases/year • giardiasis • often asymptomatic • acute or chronic diarrhea • fecal-oral life cycle • CYST • infective stage • passed in feces • TROPHOZOITE • replicative stage • small intestine

4. Adhesive Disk and Attachment

5. Pathogenesis • epithelial damage • villus blunting • crypt cell hypertrophy • cellular infiltration • malabsorbtion • enzyme deficiencies • lactase (lactose intolerance) • Possible Mechanisms • mechanical irritation • obstruction of absorption

6. Clinical Features and Symptoms • Subacute/Chronic • recurrent diarrheal episodes • cramps uncommon • sulfuric belching, ano-rexia, nausea frequent • can lead to weight loss and failure to thrive • Range of Outcomes • asymptomatic/latent • acute short-lasting diarrhea • chronic/nutritional disorders • Acute Symptoms • 1-2 week incubation • sudden explosive, watery diarrhea • bulky, frothy, greasy, foul-smelling stools • no blood or mucus • upper gastro-intestinal uneasiness, bloating, flatulence, belching, cramps, nausea, vomiting, anorexia • usually clears spontaneously (undiagnosed), but can persist or become chronic

15. Dientamoeba fragilis

17. Chilomastix mesnili

19. Trichomonas vaginalis

24. Balantidium coli

25. Balantidium coli trophozoite Balantidium coli cyst

26. Cryptosporidium • fecal-oral transmission (coccidian type life cycle) • two species infecting humans • C. parvum: cattle and other mammals • C. hominis: only humans • first human case reported in 1976 • initially believed to be rare and exotic • now known to be common human pathogen • self-limiting diarrhea in immunocompetent persons • profuse, watery diarrhea associated with AIDS (life threatening)

27. Cryptosporidium Life Cycle • Infectious form = oocyst • Sporozoites ‘invade’ intestinal epithelial cells • Merogony • produce merozoites • Gametogony • produce micro- and macrogametes • Sporogony • produce sporozoites • completed on host cell • thin (autoinfection) or thick walled oocysts

28. Diagnosis of Intestinal Protozoa • suspect: acute or chronic GI symptoms • confirmed: detection of parasite in feces • copro-antigens or molecular probes • Cryptosporidium • acid-fast stain • Giardia • 3 non-consecutive days (inconsistent excretion) • duoenal aspirates or biopsy • presumptive treatment in chronic cases

29. Cryptosporidium

32. Thank you