Amoebiasis and Giardiasis Flashcards
Entamoeba species
are taxonomically within the
subphylum ________
class ________
family _________
Sarcodina
Lobosea
Entamoebidae
Entamoeba histolytica is a/an (invasive or non-invasive?) enteric ________ parasite that is the cause of amoebiasis
invasive
protozoan
Entamoeba _______, Entamoeba _______, and Entamoeba ________ are parasites that are identical morphologically to E. _______,
dispar
moshkovskii
bangladeshi
histolytica
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
Entoameba species
________,________, and _______ cannot be distinguished by stool _______ and _______ (O&P) test
E. histolytica, E. dispar, and E. moshkovskii
ova and parasite
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
Entamoeba spp.
_______,______,_________ have occasionally been implicated as causes of diarrhea
E. polecki, Dientamoeba fragilis, and I. bütschlii
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
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
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
Epidemiology of amoebiasis
Worldwide: prevalence is about ___% to ____%
higher incidence of amoebiasis in
– developing countries.
– (male or female?) ——————, _______ and institutionalized populations.
10
50
Male ; homosexuals; travelers
Epidemiology of amoebiasis
Prevalence of amebic infection varies with level of ______ and generally higher in _______________ than in _______ climate
sanitation
tropics and subtropics
temperate
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
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
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
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
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
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
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
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
Morphology Different form of E. histolytica
_________
______ (________ nuclei)
trophozoite
cyst
1, 2, 4
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
Symptomatic infection
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
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
T
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
