Flagellates and Ciliates

• Flagellates


  Can be categorized into intestinal and atrial, movement is accomplished by flagella, some flagellates do not have a cyst form
• Flagellates


  • Trophozoite characteristics are similar to amoeba, for flagellates without cyst stages, the trophozoites are considered to be more resistant, for flagellates with both cyst and trophozoite stages, encystment and excystment can occur, flagellate cysts are equipped with a thick and protective cell wall
• Flagellates


  • Mainly reside in the small intestine, cecum, colon, duodenum, nuclear characteristics are helpful in differentiation, proper identification of structures specific to select flagellates is crucial, flagella are not always visible
• Intestinal flagellates


  • Giardia lamblia, Enteromonas hominis, Retortamonas intestinalis, Dientamoeba fragilis, Chilomastix mesnili
• Atrial flagellates


  • Trichomonas vaginalis, T. tenax, T. hominis
• Non-pathogenic flagellates


  • T. hominis, T. tenax, C. mesnili, Enteromonas hominis, Retortamonas intestinalis
• Parasitic flagellates


  • Giardia lamblia, Trichomonas vaginalis, Trichomonas tenax, Trichomonas hominis, Chilomastix mesnili, Enteromonas hominis, Retortamonas intestinalis, Dientamoeba fragilis
• Habitat of parasitic flagellates

  Lumen parasites: Duodenum and jejunum, Vagina and urethra, Mouth, Large intestine (caecum), Large intestine (caecum), Large intestine (colon), Large intestine (colon), Large intestine (caecum and colon)
• Hemoflagellates


  • Leishmania spp., Trypanosoma brucei, Trypanosoma cruzi
• Giardia lamblia


  Also known as Giardia duodenalis or Giardia intestinalis, only protozoan parasite found in the lumen of the human small intestine, inhabits duodenum and upper jejunum, most common protozoan pathogen, endemic in tropical countries where sanitation is poor, visitors to said areas develop traveller's diarrhea, is known to be a carrier of dsRNA viruses
• Giardia lamblia trophozoites


  • Pyriform or teardrop shaped, contain a pair of ovoidal nuclei, bilaterally symmetrical, possess 2 ovoid to spherical nuclei, 4 flagella, exhibit erratic tumbling motion (falling leaf/tumbling motility), supported by an axostyle, have median bodies
• Giardia lamblia cysts


  • Infective stage, has a colorless and smooth cyst wall, mature cysts usually have 4 nuclei, immature cysts usually have 2 nuclei
• Giardia lamblia life cycle

  Ingestion of cysts from hands, food, or water contaminated with human or animal feces, excyst in duodenum → trophozoites → intestinal villi, multiplication of trophozoites occur by binary fission, intestinal villi → jejunum, encyst in colon → feces
• Giardiasis/Traveler's Diarrhea


  Infections can be asymptomatic carrier state or symptomatic
• Symptomatic Giardiasis/Traveler's Diarrhea


  • May be characterized by diarrhea, abdominal cramps, anorexia, flatulence, and tenderness of the epigastric region, steatorrhea and malabsorption syndrome, severe Giardiasis can lead to the production of light-colored stools with high fat content
• Susceptibility to recurring Giardiasis

  Patients with intestinal diverticuli or IgA deficiency are more susceptible
• Acute Giardiasis


  • Patients experience abdominal pain with diarrhea, abdominal bloating, nausea, anorexia, excessive flatus with "rotten eggs" odor
• Chronic Giardiasis (Traveller's diarrhea/Gay bowels syndrome)

  • Characterized by steatorrhea, patient may manifest weight loss, profound malaise, low-grade fever, severe diarrhea is referred to as Leningrad's curse
• Diagnosis of Giardiasis


  Demonstration of G. lamblia trophozoites and cysts in stool, trophozoite in fecal smear is characterized as having "floating leaf-like motility", duodenal-jejunal aspiration or biopsy can be done, Entero-test (String test or Duodenal parasites test) requires fasting for 12 hours, Copro-antigen: ELISA and Direct fluorescent antibodies (monoclonal Abs)
• Prevention and treatment of Giardiasis

  Prevalence is linked to poor sanitation, increase prevalence is attributed to oro-anal sexual practices, improve sanitation practices, contamination by the use of night soil as fertilizer, by flies, or by infected food handlers, treatment includes Metronidazole, Tinidazole, Furazolidone, Paromomycin and Nitazoxanide
• Chilomastix mesnili


  Inhabits the cecal region of the large intestine, transmitted through ingestion of cysts in food and drinks, infections are typically asymptomatic
• Chilomastix mesnili trophozoite


  • Asymmetrically pear-shaped, has 3 anterior flagella and 1 delicate flagellum within the cytostome, exhibits stiff rotary motility in a directional pattern, nucleus is located at the anterior end, has 4 flagella, one flagellum is shorter than the others (extends to form a cytostome), structure bordering the cytostome resembles a shepherd's crook
• Chilomastix mesnili cyst


  • Pear or lemon-shaped with anterior hyaline knob, contains a single nucleus with a large central karyosome, has a well-defined cytostome
• Enteromonas hominis


  Among the non-pathogenic commensals in the large intestine (caecum), infection occurs through fecal-oral route by ingestion of cysts in contaminated food and water
• Enteromonas hominis trophozoites


  • Pear-shaped, cytoplasm contains numerous bacteria and an anteriorly placed nucleus but no cytostome, shows jerky forward motility
• Enteromonas hominis cysts


  • Oval-shaped, contains 2-4 nuclei, may mimic a two nucleated cyst of E. nana
• Retortamonas intestinalis


  Relatively small, water and food contaminated by cysts are the main source of infection, infections typically do not produce infections
• Retortamonas intestinalis trophozoites


  • Ovoid trophozoite exhibits characteristic jerky motility, single large nucleus is present in the anterior portion, small and compact central karyosome, equipped with only two anterior flagella
• Retortamonas intestinalis cysts


  • Lemon- to pear-shaped, has a single nucleus, consisting of a central karyosome, fused fibrils split up from the nucleus, forming a characteristic bird's beak appearance
• Dientamoeba fragilis


  Was previously classified as amoeba, has been reclassified as an amoeboflagellate, lacks a cyst stage, observed to be transmitted with A. lumbricoides and E. vermicularis
• Dientamoeba fragilis trophozoites


  • Irregular in shape, progressive motility is accomplished by broad hyaline pseudopods, serrated margins, contains 2 nuclei with 4-8 centrally located chromatin granules
• Dientamoeba fragilis life cycle

  Mode of transmission is person-to-person (fecal-oral route), by the eggs of Enterobius vermicularis and other nematodes, reside in the mucosal crypts of appendix, cecum, upper colon
• Dientamoeba fragilis pathogenesis


  Infection may be asymptomatic (carrier state) or symptomatic, often present with diarrhea and abdominal pain
• Atrial flagellates


  Only exist in trophozoite stage, include T. vaginalis, T. hominis, T. tenax
• Trichomonas vaginalis


  Causes the most prevalent non-viral sexually transmitted infection, lives in females - vagina and cervix, males - anterior urethra, only exists as a trophozoite
• Trichomonas vaginalis trophozoites


  • May appear ovoid, round, or pearlike, exhibits a rapid jerky motility, has 4 - 6 flagella (anterior), has a characteristic short undulating membrane, equipped with an easily recognizable axostyle
• Trichomonas vaginalis life cycle


  Completed in a single host, multiply by longitudinal binary fission, reside on the mucosal surface of the vagina in infected women, thrive in slightly alkaline/acidic pH environments, often coexists with other sexually transmitted diseases like candidiasis, gonorrhea, syphilis, human immunodeficiency virus (HIV), fomites can also transmit the infection
• Trichomoniasis


  Referred to as "ping pong disease", can occur in males and females, often coexists with other sexually transmitted diseases including candidiasis, gonorrhoea, syphilis, HIV, babies may acquire infection during birth from infected mothers, fomites have been implicated in transmission
• Trichomoniasis in females


  • Proliferating colonies cause degeneration and desquamation of the vaginal epithelium, secrete cysteine proteases, lactic acid, and acetic acid, greenish or yellow vaginal fluid (fishy odor and frothy; itchy and burning sensation), chronic infection leads to increased epithelial cells and establishment of mixed bacterial flora, speculum examination may reveal strawberry cervix
• Trichomoniasis in males


  • Are often asymptomatic, irritating persistent and recurring urethritis occurs in some cases, prostatitis is the most common complication