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64 Cards in this Set
- Front
- Back
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Fecal-Oral Transmission Factors
What are the poor personal hygiene factors? |
children (eg, day-care centers)
institutions (eg, prisons, mental hospitals, orphanages) food handlers |
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Fecal-Oral Transmission Factors
What are the issues with developing countries? |
poor sanitation
lack of indoor plumbing endemic travelers' diarrhea |
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Fecal-Oral Transmission Factors
- what cause water-borne epidemics? |
water treatment failures
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Fecal-Oral Transmission Factors
- what are the risk factors for homosexuals? |
oral-anal contact
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Fecal-Oral Transmission Factors
- Is zoonosis an issue? |
Entamoeba = no
Cryptosporidium = yes Giardia = controversial |
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Intestinal protozoa - which ones are flagellates?
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Giardia lamblia
Dientamoeba fragilis Pentatrichomonas hominis Chilomastix mesnili Enteromonas hominis Retortamonas intestinalis |
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Intestinal protozoa - which ones are amebas?
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Entamoeba histolytica
Entamoeba dispar Entamoeba coli Entamoeba hartmanni Endolimax nana Iodamoeba bütschlii |
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Intestinal protozoa - which ones are apicomplexa?
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Cryptosporidium hominis
Cryptosporidium parvum Cyclospora cayetanensis Isospora belli |
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Intestinal protozoa - which ones are the others?
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Blastocystis hominis
Balantidium coli |
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Intestinal protozoa - which stage is infective?
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cysts - they are passed in feces and are resistant
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What are the other lumen-dwelling protozoa?
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Other Lumen-Dwelling Protozoa
Trichomonas vaginalis (urogenital) Trichomonas tenax (oral) Entamoeba gingivalis (oral) |
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What are the life cycle characteristics of trophozoites?
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feeding
motile replicative |
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Giardia lambia, trophozoite
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Who am I and what stage?
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What is the most common protozoa in stools?
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giardia lambia
most common protozoa in stools ~200 million clinical cases/yr |
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How many taxonomy species of giarida are there?
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Taxonomy
one human species, aka: G. duodenalis G. intestinalis morphologically similar forms in other mammals |
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Who first observed giardia?
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1681 van Leeuwenhoek observed
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Who first document clinical symptoms of giardia
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1859 Lambl documented
1920’s clinical symptoms, but controversial 1954 Rendtorff fulfilled Koch’s postulate |
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What are the transmission factors of giardia?
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Fecal-Oral Transmission Factors
- poor personal hygiene -- children (eg, day care centers) -- food handlers developing countries -- poor sanitation -- endemic -- travelers diarrhea water-borne epidemics zoonosis? -- Entamoeba =no -- Cryptosporidium =yes -- Giardia =controversial |
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Is giardiasis a zoonsis?
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Is giardiasis a zoonosis?
limited documentation transmission between humans and dogs rare (J.Parasit. 83:44, 1997) person-to-person trans-mission is most prevalent |
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How many clades are human isolates found in giardiasis?
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human isolates only found in clades A and B
Giardia relatively host specific zoonotic transmission relatively rare virulence? |
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What are the in vitro culture excystation features of giardia?
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Excystation
brief exposure to acidic pH (~2) flagellar activity within 5-10 min after return to neutral pH breakdown of cyst wall (proteases) trophozoite emerges from cyst cytokinesis within 30 min |
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What are the in vitro culture encystation features of giardia?
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growth at pH 7, no bile
exposure to pH 7.8, high bile cyst wall secretion (appearance of vesicles) loss of disk and flagella nuclear division |
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microtubules
tubulin microribbons giardins lateral crest actin-myosin |
What are the adhesive disk components of giardia?
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what are the attachement mechanisms of giardiasis?
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- Attachment Mechanisms?
contractile force receptor mediated |
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What are the range of outcomes with giardiasis?
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asymptomatic/latent
acute short-lasting diarrhea chronic/nutritional disorders |
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What are the subacute/chronic symptoms of giardiasis?
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recurrent diarrheal episodes
cramps uncommon sulfuric belching, ano-rexia, nausea frequent can lead to weight loss and failure to thrive |
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What are the acute symptoms of giardiasis?
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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 and become chronic |
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What are the possible mechanisms of pathogenesis for giardiasis?
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mechanical irritation
inflammation |
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- epithelial damage
-- villus blunting -- crypt cell hypertrophy -- some inflammation - electrolyte transport -- malabsorption of glucose, Na+, water, etc -- hypersecretion of Cl- - enzyme deficiencies -- lactase → lactose intolerance |
What is the pathogenesis of giardiasis?
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What is a confirmed diagnsis of giardiasis?
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confirmed: detection of parasite in feces or duodenal aspirate or biopsy
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What are the lab issues with giardiasis?
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parasite easy to identify
parasite can be difficult to detect inconsistent excretion in feces patchy loci of infection |
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How do you diagnose giaridasis via parasite detection?
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Parasite Detection
Stools 3 non-consecutive days wet mounts or stained IFA, copro-antigens Aspirate or Biopsy Enterotest (or string test) |
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How do you treat giardiais?
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Drug of Choice
metronidazole (Flagyl) 750 mg/tid/5d >90% cure rate Alternatives tinidazole (single dose) paromomycin (pregnancy) quinicrine furazolidone Prognosis is good and generally with no sequelae |
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How do you control giardiasis?
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avoid fecal-oral transmission
improve personal hygiene - especially institutions treat asymptomatic carriers - eg, family members health education - hand-washing - sanitation - food handling protect water supply treat water if questionable - boiling - iodine - not chlorine |
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where does giardia inhabit?
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small intestine - duodenum
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How many cysts do you need to get infected with giardiasis?
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10
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Describe basic morphology of trichomonads
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3-5 anterior flagella
one undulating membrane axostyle hydrogensome (EM) |
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cave
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a deep, hollowed-out area under the earth's surface
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Trichomonad
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Who am I?
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How is trichomonas vaginalis transmitted?
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trophozoite stage transmitted during sexual intercourse
- non-sexual contact possible common STD - co-infection w/other STDs - more prevalent in at risk groups |
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What specific tissue is trichomonas vaginalis attacted to?
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associated with epithelium of uro-genital tract
- females: vagina - males: urethra, prostate, epididymis |
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Who is more susceptible to getting trichomonas vaginallis?
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both sexes equally susceptible
symptoms more common in females |
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What is the clinical presentation of trichomonas vaginalis in females?
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ranges from asymptomatic, to mild or moderate irritation, to extreme vaginitis
- 50-75% abnormal discharge (frothy, yellowish or greenish) - 25-50% pruritis - 50% painful coitus onset or exacerbation often associated with menstruation or pregnancy vaginal erythema, ‘strawberry cervix’ (~2%) |
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What is the clinical presentation of trichomonas vaginalis in males?
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50-90% are asymptomatic
mild dysuria or pruritus minor urethral discharge |
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HIV and Trichomoniasis - How does trich affect one's immunity and how does that relate to HIV?
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Leukocyte infiltration and lesions may increase target cells (CD4, MΦ) for HIV
- increased inflammatory response is localized in the sexual organs |
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HIV and Trichomoniasis - how does it effect transmission?
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Trichomonas infections may enhance HIV transmission by 1.5-3X
Possible increased level of HIV-infected cells in genital area during co-infection ↑ cervical shedding of HIV ↑ viral loads in semen |
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Ho do you diagnose trichomoniasis?
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demonstration of parasite
direct observation or in vitro culture - vaginal discharge - urine sediment - prostatic secretion |
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How do you txt trich?
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metronidazole (Flagyl)
- 250 mg (3/d) for 5-7 days - single 2 g dose simultaneous treatment of partner! (85-90% cure rate) |
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How do you prevent trich?
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limit # of sexual partners
condoms |
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what is unique about dientamoeba fragilis' life cycle?
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has no cyst stage, only trophozoites
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What is morphologically unique about dientamoeba fragilis?
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it is often binucleated
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How is dientamoeba fragilis transmitted?
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- it has no cyst stage, only trophozoites
- transmission via the pinworm Enterobius vermicularis? - 15-30% of infections associated with diarrhea and other GI symptoms |
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how do you treat dientamoeba fragilis?
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iodoquinol is drug of choice
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What is unique about ciliates?
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covered with rows of cilia
defining characteristic is nuclear dimorphism micronucleus (genetic) macronucleus (somatic) sexual reproduction involving conjugation |
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How many ciliates infect humans?
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Despite being a large and diverse group - majority free-living - only Balantidium coli infect humans
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How do ciliates reproduce?
Describe pathways |
asexually and sexually.
Asexually - trophozoites replicate by binary fission in which both the macro- and micornucleus undergo mitosis and each of the daughter cells receives copies of both. -- DNA synthesis, mitosis, cytokinesis - Sexually - Trophozoites pair and exchange nuclei during sexual reproduction. -- macronucleus formation -> pairing and meiosis --> loss of macronuculeus and 3 micronuclei --> mitosis and nuclei exchange --> nuclear fusion and speration |
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Where do you geographically see Balantidium coli?
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world-wide distribution
- especially prevalent in tropics - rarely exceeds 1% common in pigs and monkeys - unlikely to be reservoirs |
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Describe where B coli reside and basic pathology
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usually non-pathogenic commensal in colon
can invade intestinal epithelium and cause ulceration with dysentery-like symptoms |
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What are the symtpoms of balantidosis (balantidiasis or balantidial dysentery)
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symptoms: acute diarrhea with mucus and blood, cramps
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How do you diagnose balantidosis?
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diagnosis: identify cyst or trophozoite in feces
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How do you treat balantidosis?
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tetracycline or iodoquinol
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Balantidium coli
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Who am I?
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Blastocyctis hominis
- big blob - vacuole - smaller blobs ontop - nuclei |
Who am I? What is the big blob in the middle and smaller blobs on top?
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What is the presumed pathology of blastocystis hominis?
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pathology debated
GI symptoms (diarrhea, cramping, etc) in some cases treatment alleviates symptoms - life cylce and mode of transmission unknown - presumed fecal oral |
