Tissue and Intestinal Flagellates Practical parasitology Dr. Ayham Abulaila

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

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

Adhesive Disk and Attachment

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

Clinical Features and Symptoms 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 Subacute/Chronic recurrent diarrheal episodes cramps uncommon sulfuric belching, ano- rexia, nausea frequent can lead to weight loss and failure to thrive

Dientamoeba fragilis

Chilomastix mesnili

Trichomonas vaginalis

Balantidium coli

Balantidium coli trophozoite Balantidium coli cyst

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)

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

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

Cryptosporidium

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