Amoebiasis and Giardiasis Flashcards by Iseoluwa Ojo

Entamoeba species

are taxonomically within the

subphylum ________

class ________

family _________

Sarcodina

Lobosea

Entamoebidae

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Entamoeba histolytica is a/an (invasive or non-invasive?) enteric ________ parasite that is the cause of amoebiasis

invasive

protozoan

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Entamoeba _______, Entamoeba _______, and Entamoeba ________ are parasites that are identical morphologically to E. _______,

dispar

moshkovskii

bangladeshi

histolytica

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Entoameba species

E. dispar is (pathogenic or nonpathogenic?)

E. moshkovskii causes (invasive or noninvasive?) diarrhea

E. bangladeshi is of (known or unknown?) virulence.

nonpathogenic

noninvasive

unknown

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Entoameba species

________,________, and _______ cannot be distinguished by stool _______ and _______ (O&P) test

E. histolytica, E. dispar, and E. moshkovskii

ova and parasite

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Entamoeba spp.
At least seven additional species of amebae

(Entamoeba _______ , Entamoeba _______, Entamoeba _______, Entamoeba _______, _______ _______ , _______ _______, and _______ _______) infect the human intestine but are generally accepted as _______ organisms

Entamoeba coli
Entamoeba hartmanni
Entamoeba polecki
Entamoeba chattoni
Dientamoeba fragilis
Iodamoeba bütschlii
Endolimax nana

commensal

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Entamoeba spp.

_______,______,_________ have occasionally been implicated as causes of diarrhea

E. polecki, Dientamoeba fragilis, and I. bütschlii

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Amoebiasis is defined as _______ infection by _________ species, including E. histolytica, which is the cause of ________,_________, and rarely, ______

human

Entamoeba

amebic colitis, liver abscess

brain abscess

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HISTORY 1875 LOSCH – RUSSIAN.

Differentiated the ______ dysentery from ________ dysentery by describing _______

1887 KARTULIS – EGYPT. Found _____________ from a liver abscess.

amoebic; bacillary; amoeba in the stool.

amoeba in the pus

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HISTORY

1881 COUNCILMAN AND COFFLEUR. Described _________ and used the term _________

1903 SCHAUDINN. Differentiated __________ and _________ types of amoeba

true bowel lesions

Amoebic Dysentery.

pathogenic and non pathogenic

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Epidemiology of amoebiasis

Worldwide: prevalence is about ___% to ____%

higher incidence of amoebiasis in
– developing countries.
– (male or female?) ——————, _______ and institutionalized populations.

Male ; homosexuals; travelers

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Epidemiology of amoebiasis

Prevalence of amebic infection varies with level of ______ and generally higher in _______________ than in _______ climate

sanitation

tropics and subtropics

temperate

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Epidemiology of amoebiasis

_____ passers are important source of infection

_______________ is the second leading cause of mortality due to parasitic disease in humans. (The first being _________).

Cyst

Entamoeba histolytica

malaria

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Epidemiology of amoebiasis

____________ is the second leading cause of mortality due to parasitic disease in humans. (The first being ________).

Amebiasis is the cause of an estimated _____-________ deaths each year.

Entamoeba histolytica

malaria

50,000- 100,000

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Transmission of amoebiasis

___________

sexual transmission among _____________ (_______-______)

Food or drink contaminated with _______ containing ___________

Use of human feces (night soil) for soil fertilizer by flies, and possibly cockroaches

Faeco-oral

homosexual males; oral- anal

feces containing the E.histolytica cyst

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Pathogenic mechanisms of anoebiasis

receptor-mediated __________________ ( ______________ )

secreting _______ enzymes(________ ) and ________ substances.

contact-dependent _________/________ of target cell

____________ - amoebic ________ of killed target cell

adherence of amebae to target cell; adherence lectin

proteolytic; histolysine; cytotoxic

cell killing/amebic cytolysis

cytophagocytosis; phagocytosis

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PATHOGENESIS of amoebiasis

The pathogenesis of amoebiasis centers on the unique ________ properties for which the organism was named histolytica.

Tissue invasion involves a ______-dependent process

Parasite binds to the _________ layer of host’s colonic epithelium by the parasite’s ____________, .

________ host’s immune mechanisms and destroys host’s cells

invade the intestinal epithelium and form ________ with a _________ center and ______ edges, from which ____,________, and ________ pass.

The ________ multiply and accumulate above the _________, often spreading _______.

Rapid lateral spread of the multiplying amebae follows, undermining the mucosa and producing the characteristic “___________ ” ulcer of primary amoebiasis

tissue-destructive

contact; mucin

Gal/GalNAc lectin; Overcomes

discrete ulcers; pinhead-sized ; raised

mucus, necrotic cells, and amebae

trophozoites; muscularis mucosae; laterally

flask-shaped

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Pathogenesis of Amoebiasis

Trophozoites may penetrate the ______ layers and occasionally the ______, leading to perforation into the ___________

Subsequent _______ of the necrotic area produces gross changes in the ulcer, which may develop ____________________

Secondary bacterial invasion, and accumulation of neutrophilic leukocytes.

Lesions may extend to other parts of the GIT

An amebic ___________ or _________________________ mass (ameboma) may form on the intestinal wall and may lead to ________________

muscle; serosa; peritoneal cavity.

enlargement; shaggy overhanging edges

inflammatory or granulomatous tumor-like

intestinal obstruction

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E. histolytica is found primarily in the _____ where it can live as a ______________ or invade the intestinal mucosa (green).

The ameba can metastasize to other organs via a _______ route (purple); primarily involving the _______ and ______.

The ameba can also spread via a _________ (blue) causing a ______ infection, ______ lesions or ______ ulcers.

colon

non- pathogenic commensal

hematogenous

portal vein and liver

direct expansion ; pulmonary; cutaneous; perianal

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Factors that determine invasion of amoebae

the ________ of amebae ingested,

the _______________ of the parasite strain

host factors such as _________

______________ of the host, susceptibility of the host; ________ status

the presence of _______________ that enhance amebic growth

number

pathogenic capacity/ virulence

gut motility

immune competence

nutrition; suitable enteric bacteria

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Morphology Different form of E. histolytica

_________

______ (________ nuclei)

trophozoite

cyst

1, 2, 4

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Trophozoite of amoeba

•Size:12-60μm in diameter

•(Invasive or Non-invasive?) form ( minuta) / E. _____

•(Invasive or Non-invasive?) form (magna) contain _____, E. ________

Non-invasive; dispar

Invasive ; RBC; histolytica

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Symptomatic infection

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Symptomatic infection

Can either be A or B

A can be divided into C and D

B can be divided into E, F, G

A= Intestinal Amebiasis

B= Extraintestinal Amebiasis

C= Diarrhoea

D= Dysenteric colitis

E= hepatic

F=pulmonary

G=extra foci

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Clinical manifestation of amoebaiasis •Asymptomatic cystic passage/ carrier Risk to _________ as a __________ Risk of __________ to the host •Amoebic ______________

community; source of new infection invasive disease diarrhea

Clinical manifestation of amoebaiasis Amoebic dysentry = _________+_______+____________ in patient with E.histolytica infection •(Gradual or Sudden?) onset of symptoms over ______ •Increasing ______ + abdominal ________ •_____ may be absent

Amoebic diarrhoea + mucus +visible or microscopic bloo Gradual ; 3-4weeks severe diarrhoea ; tenderness Fever

Complications of Amoebiasis List 5

Perforation Ameboma intestinal obstruction Necrotizing colitis Toxic megacolon Intussception

Extraintestinal infections(metastatic amoebiasis) metastatic is due to _______, rarely occurs by _________ from the bowel most common form is ________,_________ others include: amoebic empyema, amoebic ________ abscess, amoebic _______ abscess.

micro emboli; direct extension amoebic hepatitis or liver abscess pericardial; cerebral

Extraintestinal infections(metastatic amoebiasis) A true amebic abscess is ______,__________(unless secondarily infected), and _______ without __________ and ___________ The contents are _____ and bacteriologically _____, active amebae being ____________

progressive, nonsuppurative destructive compression and formation of a wall. necrotic; sterile ; confined to the walls.

Extraintestinal infections(metastatic amoebiasis) A characteristic “_________” is produced in the abscess and seen on surgical drainage

anchovy paste

Amoebic liver abscess 10x more common in (men or women?) than (men or women?) Symptoms: fever, cough, rt upper quadrant or epigastric pain May be associated with GIT symptoms : nausea, vomiting, abdominal cramp , abdominal distention, diarrhoea, constipation

men than women

Amoebic liver abscess Lab findings:_________, abnormal ____________ Defect in hepatic imaging study

leukocytosis liver enzymes

Amoebic liver abscess Amoeba is usually (present or absent?) from stool at the time of diagnosis Differential diagnosis: –__________ –_________

Absent Hepatoma Echinococcal cysts

Diagnosis of amoebiasis clinical Diagnosis: Sigmoidoscopic examination: presence of a _______ mucosa between the ____ serves to differentiate amebic from bacillary dysentery,( the _______________ in bacillary dysentery). ______megally FBC. : leukocytosis in Amebic dysentery rises above 12000 per microliter, but counts may reach 16000 to 20000 per microliter.

grossly normal; ulcers entire mucosa being involved Hepato

Diagnosis of amoebiasis clinical Diagnosis: Entamoeba histolytica must be differentiated from other intestinal protozoa including: ________,______,______ Differentiation is possible, but not always easy, based on morphologic characteristics of the cysts and trophozoites. The nonpathogenic Entamoeba ______, however, is morphologically (identical to or different from?) E. histolytica, and differentiation must be based on isoenzymatic or immunologic analysis. Molecular methods are also useful in distinguishing between E. histolytica and E. dispar and can also be used to identify E. polecki.

E. coli, E. hartmanni, E. dispar dispar identical to

Microscopy (Stool Ova and Parasite Examination) of amoebiasis Microscopic identification This can be accomplished using: Fresh stool:_____ mounts, ______ mounts and ______________ preparations (e.g., _______). Concentrates from fresh stool: wet mounts, with or without ____ stain, and permanently stained preparations (e.g., __________).

wet; iodine; permanently stained ; trichrome iodine; trichrome

In the absence of ____________, the pathogenic E. histolytica is morphologically indistinguishable from the nonpathogenic E. dispar!

erythrophagocytosis

____________________ is the only morphologic characteristic that can be used to differentiate E. histolytica from the nonpathogenic E. dispar.

Erythrophagocytosis

Antigen Detection in amoebiasis Antigen detection may be useful as ______ to ________ diagnosis in detecting parasites and to distinguish between pathogenic and nonpathogenic infections.

An adjunct microscopic

Culture of E. histolytica from stool samples is available in ————- research laboratories worldwide Culture is, in general, (more or less?) sensitive than stool O&P examination but significantly (more or less?) sensitive than culture and serology

only a few More Less

Molecular diagnosis ______ is the method of choice for discriminating between the pathogenic species (E. histolytica) from the (nonpathogenic species (E. dispar.

PCR

Prevention and control of amoebiasis Prevention of ___________ of food and water use of __________ in men who have sex with men proper maintenance of municipal water supplies to prevent access of ——————— to the treated water supply.

fecal contamination safe sexual practices chlorine resistant amebic cysts

Serology serology Antibody detection or Antigen detection The indirect hemagglutination (IHA) Rapid latex agglutination tests Immunobloting The EIA test detects antibody specific for E. histolytica in approximately 95% of patients with _________ amebiasis, 70% of patients with __________ infection, and 10% of _______ persons who are _______________________

extraintestinal active intestinal asymptomatic passing cysts of E. histolytica

Difference between E. histolytica and E.coli Xterics : Histolytica: Coli Size of cysts Nuclei Size of trophozoites Erythrophagia Intracellular karyosomes Ring of nuclear chromatin Cytoplasm Movement

12-14um; 10-35um 4;8 10-10um; 10-50um Present ; absent Tiny and centrally placed; Large and eccentric Evenly dispersed, beadlike; Blotchy distribution Smooth, finely granular; Rough Unidirectional motility extends pseudopods only in one plane; Moves in different directions. extends pseudopods multiple planes

Giardia lamblia also known as G._______ or G. _______ A _________ pathogenic protozoan found in the _______ and _______ of humans

intestinalis; duodenalis flagellated duodenum and jejunum

Giardia lamblia a common cause of ____,______,_______, and ______ diarrhea throughout the world

sporadic, endemic, and epidemic

Giardia lamblia 1600s- van Leeuwenhoek discovered it in ____________. in the early ______ that the parasite received the genus name Giardia.

his own stool 1900s

Giardiasis Prevalence -______% in industrialized countries ________% in developing countries • Caused by Giardia ________/ Giardia _____

2-5 20-30 intestinalis lamblia

Giardiasis •______ is the main reservoir • Inhabit ___________________________

Man duodenum, jejunum & upper ileum

Giardia is one of the most widely distributed enteric parasites. T/F

Giardia it is most frequently reported in children aged ______ years and adults aged ________ years. In low-income countries, Giardia infects nearly ____ children by the age of ____ years.

1 to 9; 35 to 45 all; 10

Giardia Commoner among ________ children Transmission of this ______ parasite is most common through person to person

malnourished fecal-oral

Transmission of Giardia Infective form –_______ passed in feces of man • Routes of transmission –______, ______________ – most important Ingestion of contaminated food Person to person – day care, nursing homes, mental asylums (poor hygiene and formites) – Sexual – ——————————

mature cyst Feco-oral ingestion of contaminated water sexually active homosexual males

Giardia Life cycle composed of two stages: the _________, or freely living stage the ______.

trophozoite cyst

Morphology of Giardia lamblia trophozoite ______ shaped, _____ anterior end, posterior end ______ (looks like _______ face)

Pear; rounded; pointed; monkey

Morphology of Giardia lamblia trophozoite Size: 12 to 15 μm long x 5 to 9 μm wide Dorsal surface _____, ventral surface _______ Ventral surface bears ________ to adhere to surface of ___________

convex; concave sucking disk; intestinal cell

Morphology of Giardia lamblia trophozoite Bilaterally symetrical: 2 ______, 2 _______, 4 _____________ (2 anterior, 2 posterior, 2 ventral, and 2 caudal) actively motile and feeding stage Habitat: _____________ May invade the __________

nuclei; axostyles pairs of flagella small intestine common bile duct.

Trophozoite of Giardia Size is a ______-shaped organism has _____ pairs of flagella approximately 15 μm in length (:9 to 21 μm long and 5 to 15 μm wide).

heart; four

Trophozoite of Giardia A (small or large?) (concave or convex?) ________ on the (ventral or dorsal?) surface helps the organism to adhere to intestinal villi

Large ; concave; sucking disk Ventral

Trophozoites of Giardia As the parasites pass into the colon, they typically _______, and the ______ are passed in the stool. They are _______, (thin or thick?) -walled, (mild or highly?) resistant, and 8–14 μm in length they contain _____ nuclei as immature forms and _____ as mature cysts.

encyst; cysts ellipsoid; thick; highly two; four

Life cycle of Giardia Infection acquired by – ingestion of _______ ___________ occurs in stomach & duodenum within __________ _____________ hatch from one cyst Trophozoites multiply by ___________ & colonize in duodenum & upper jejunum Trophozoites adhere to ______ by _________ _________ occurs in transit down the colon Axonemes retract, cytoplasm condense & thin tough hyaline wall is secreted __________ undergo nuclear division –mature ________nucleate cyst

mature cysts Excystation ; 30 minutes 2 trophozoites; binary fission enterocytes; ventral suckers Encystation Encysted trophozoite; quadrinucleate

Life cycle of Giardia Infection occurs by _________ of as few as ____________ incubation period- __________ After _________, trophozoites colonize and multiply in the upper small bowel. Adherence in the human gut is most likely via the ______, with attachment at the brush border of enterocytes by either a _______ or a _______ mechanism.

ingestion; 10-25 cysts 1 to 2 weeks excystation; ventral disk suction or a clasping

Pathogenesis of Giardiasis pathogenic mechanisms include: – disruption of the ______________________, _______ invasion -elaboration of an _______ – Disruption of __________ – increase _________ -induction of ___________

intestinal epithelial brush border and function mucosal; enterotoxin tight junctions; permeability apoptosis

Pathology of Giardiasis Do not __________ Feed on _________ May localize in ______ to avoid the acidity of duodenum Cause ______ of duodenum & jejunum Cause ________ as the parasite coats the mucosa & damage epithelial brush border Stool contains large amounts of ______ and _______ but no _______

invade tissues; mucous secretions biliary tract ; inflammation malabsorption mucous & fat but no blood

Giardiasis Initially, stools may be _______ and _______, but later they are commonly ——-,————-, and _________ Patients who develop chronic diarrhea have profound malaise, lassitude, occasional headache, and diffuse abdominal and epigastric discomfort often exacerbated by _______. Stools may be ______ and _____ or _____,_______, occurring in small volume, and frequently passed. Weight loss is usually (present or absent?)

profuse and watery greasy, foul smelling, and may float eating greasy and foul smelling ; frothy, yellowish present

Clinical features of giardiasis Asymptomatic : largest group,_______ Acute :_______ infection, acute _____ diarrhoea, abdominal _____, bloating, _________. Stool is _____ and ______ in earlier disease. ____,_______, and ______(____) later Chronic : chronic diarrhoea with ________ syndrome, __________

cyst passage self-limiting; watery; cramps; flatulence profuse & watery Voluminous foul smelling & greasy (steatorrhoea) malabsorption; steatorrhoea

Complication of Giardiasis ________________ syndrome Failure to ______ Post-Giardia ___________ Chronic ______ syndrome Post-Giardia ____________ Extraintestinal manifestations : urticaria, other skin rashes, reactive arthritis, eye complaints, biliary tract disease, and gastric infection Gastric infection occurs exclusively in the presence of _________

Malabsorption; thrive irritable bowel syndrome fatigue; lactose intolerance achlorhydria

Treatment of Giardiasis _______ is the drug of choice, taken in a single dose Alternatives are – ______,_______,______

Tinidazole Metronidazole Nitazoxanide albendazole.

chlorination of water affects the cysts T/F

F chlorination of water does not effect the cysts