Transcript 06-E histolytica lecture& Free living Amoeba.ppt

Causal Agent:
• Several protozoan species in the genus
Entamoeba infect humans, but not all of
them are associated with disease.
• Entamoeba histolytica is well recognized as
a pathogenic ameba, associated with
intestinal and extra-intestinal infections.
• The other species are important because
they may be confused with
E. histolytica in diagnostic investigations.
Introduction
Entamoeba histolytica
1. The only pathogenic amoeba
among all of the intestinal
amoebae.
2. Infecting perhaps 10% of the
world's population.
3. Lead to invasive amoebiasis.
Entamoeba histolytica
• Worldwide, with higher incidence
of amoebiasis in developing
countries.
• risk groups include male
homosexuals, travelers and recent
immigrants, and institutional
populations.
morphology
•
•
•
•
Life cycle
Infection by Entamoeba histolytica
occurs by ingestion of mature cysts in
fecally contaminated food, water, or
hands.
Excystation occurs in the small
intestine and trophozoites are released,
which migrate to the large intestine.
The trophozoites multiply by binary
fission and produce cysts.
Cysts and trophozoites are passed in
feces Cysts are found in formed stool,
whereas trophozoites are found in
diarrheal stool.
E.dispar has
similar live
cycle but non
invasive ,not
pathogenic.
Viability : -Moist
,cool condtion Up
to 12days -In
water 9-30 day
Via polluted water;
infected food
handler, flies
contaminating food,
soil cultivation,
direct contact
transmission.
the cysts can survive days to weeks in
the external environment (protection by
cyst walls) and are responsible for
transmission.
• Trophozoites in the stool are rapidly
destroyed outside ,and if ingested not
survive in the gastric juice.
• In many cases, the trophozoites remain
confined to the intestinal lumen of
individuals who are known as (non-invasive
infection) cyst passer.
•
1
2
3
4
1- the primary ulcer invasion of
mucosa via crypts repair may
occur.
2- extension in mucosa muscularis
mucosa relatively resistant.
3-formation of sinus accumulation
of amoebae superficial to
muscularis mucosa with lateral
extension of lytic necrosis;
abscesses may coalesce under
intact mucosa , mucosa may
slough with widespread
ulceration
4-deep extension
muscularis mucosa eventually
pierced (direct or via blood)
deep necrosis of sub-mucosa
even muscle and sub-serosa
Complications and squeals
-Perforation
hemorrhage
(rare)
-Secondary
infection
Amoeboma
Obestraction
-Pretonitis haemorrhag
-Surronging inflammatory
reaction
-A mass under oedemotous
mucosa
intusssception
Amoeboma clinically
simulates neoplasm
-Invasion of
blood vessels.
-Extraintestinal lesion
-Direct extension
outside bowel
-Ulcer with peritonitis
- hemorrhage
- surrounding inflammatory reaction
and fibroplastic proliferation a
mass formed under edematous
mucosa amoeboma (simulate carcinoma)
Extra intestinal extension
Extra intestinal extension
Liver involvement
- Secondary to
- Concomitant with
- Independent of
.
A
B
• the pathogenic E. histolytica is not
morphologically differs from the
nonpathogenic E. dispar!
• Each trophozoite has a single nucleus,
which has a centrally karyosome and
uniformly distributed peripheral
chromatin.
• The cytoplasm has a granular or
"ground-glass" appearance.
• Entamoeba histolytica / E. dispar
trophozoites measure usually 15 to 20
µm (range 10 to 60 µm), tending to be
more elongated in diarrheal stool.
C
D
erythro-phagocytosis,
e
f
Trophozoites of Entamoeba histolytica
with ingested erythrocytes .The ingested
erythrocytes appear as dark inclusions.
• Erythro-phagocytosis
is the only morphologic
characteristic that can be used
to differentiate E. histolytica
from the non-pathogenic
E. dispar
• The nuclei of Entamoeba
histolytica have characteristically
centrally located karyosomes, and
fine, uniformly distributed
peripheral chromatin.
• The cysts contain chromatoid
bodies , with typically blunted
ends.
• Entamoeba histolytica cysts
usually measure 12 to 15 µm.
MatureEntamoeba histolytica cysts usually
measure 12 to 15 µm. cysts have 4 nuclei.
h
I
Entamoeba coli
Trophozoites of Entamoeba coli
B
A
C
• Entamoeba coli
-Trophozoites each have one nucleus
with a large, eccentric karyosome and
coarse, irregular peripheral
chromatin.
-The cytoplasm is coarse , vacuolated
(dirty cytoplasm).
- Cytoplasm contains ingested bacteria
, yeasts or other materials.
- The trophozoites of E. coli measure
usually 20 to 25 µm, but it can reach
up to 50 µm.
• Mature cysts typically have
8 nuclei, and measure about
20-25 µm (range 10 to 35 µm).
• Chromatoid bodies are seen less
frequently than in E.histolytica. they
are splinter like with pointed ends.
• N.B. chromatoid bodies of
E.histolytica have rounded ends.
Entamoeba coli cyst
E
D
F
Clinical Features:
A wide spectrum, from asymptomatic
infection ("luminal amebiasis"), to
invasive intestinal amebiasis
(dysentery, colitis, appendicitis, toxic
megacolon, amebomas), to invasive
extra-intestinal amebiasis
(liver abscess, peritonitis,
pleuropulmonary abscess, cutaneous
and genital amebic lesions).
pinpoint lesion on mucous membrane
flask-shaped (Ulcers)
Amoebic abscess in liver
Pathogenesis:
Clinical classification
•
Intestinal
Asymptomatic infection
(carrier) 85-95 % of cases.
• Sympomatic cases 5-15%
a. Intestinal amoebiasis
- a. dysentery
(blood and mucus in stool)
- b. non-dysenteric colitis
- c. amoeboma
b.Extra-intestinal amoebiasis
a. Hepatic
(1) acute non suppurative
hepatitis
(2) liver abscess
b. Pulmonary
c. Brain, Skin, Other extraintestinal amoebiasis.
Hepatic amoebiasis:
sing & symptoms
• Local discomfort.
• Malaise, fluctuant temperature
• Toxemia.
• Pain in right shoulder.
Diagnosis : intestinal
Direct
_ Microscopic identification of cysts
and trophozoites in the stool
_ trophozoites can also be identified in
aspirates or biopsy samples obtained
during colonoscopy or surgery.
Indirect by immunodiagnosis (elisa)
Diagnosis: of Amoebic liver
abscess
• X-ray or ct scan show raised
diaphragm
• Blood picture –leucoytosis.
• Serological test (elisa).
• Examination of aspirate if
indicated as treatment.
• Treatment:
-For asymptomatic infections,
(furamide) is the drugs of choice.
-For symptomatic intestinal disease,
or extra intestinal, infections
(e.g. hepatic abscess), the drugs of
choice are metronidazole or
tinidazole, immediately followed by
treatment with diloxanide furoate.
Prevention
• human feces should not be used
as fertilizer
• food and drinks must be
protected from flies.
(mechanical transmission)
• personal hygiene.
wash hands after defecation and
before meals. (autoinfection)
in summary
pinpoint lesion on mucous membrane
• flask-shaped Ulcers
• Amoebic liver abscess
• anchovy sauce sputum (lung)
• brain , spleen , genito-urinary tract
• amoeboma simulate carcinoma.
- Cyst carrier is a healthy persons
(trophozoite only in intestinal lumen Lumenal form).
- Pre-employments Stool analysis was done
for food handler.
FREE-LIVING PROTOZOA
Ameba Diseases
• Naegleria fowleri
PAM
• Acanthamoeba spp.
GAE,
skin or lung lesions,
amebic keratitis.
Acanthameoba
Have only 2 stage cyst And
trophozoite.
• Trophozoite and cyst are infective
form.
• portal of entry unknown, possibly
respiratory tract, eyes, skin.
• presumed hematogenous
dissemination to the CNS.
•
Acanthamoeba Encephalitis
• infection associated with debilitation
or immunosuppression. opportunistic
parasitic inf.
• chronic GAE (granulomatous amebic
encephalitis). the organisms cause a
granulomatous encephalitis that leads
to death.
• occurred in wearers of contact
lenses.
Amebic Keratitis
• Predisposing factors
ocular trauma, contact lens
(contaminated cleaning solutions).
• Symptoms ocular pain, corneal lesions
(refractory to usual treatments).
• Diagnosis
demonstration of amebas in corneal
scrapings.
• Treatment
difficult, limited success
corneal grafts often required.
Naegleria fowleri
• found in fresh water.
• ameba with loblose
Pseudopodia.
• motile bi-flagellated form.
• PAM first recognized by
Fowler (1965).
Primary Amebic Meningoencephalitis
(PAM)
• Symptoms usually within a few
days after swimming in warm still
waters.
• Infection believed to be
introduced through nasal cavity
and olfactory bulbs.
• Symptoms include headache,
disorientation, coma.
Clinical picture
A-Asymptomatic infection majority ,
about 80%
B-Symptomatic infection:
1* typical picture most of symptomatic
cases: incubation period 1-2 weeks
followed by diarrhea for bout 6 weeks.
2* atypical picture
- malabsorption in children
- fatty diahrrea
- Sever diarrhoea.
Laboratory diagnosis
-Stool examination daily for three days.
-Examination of duodenal aspirate,
or by string (enterotest)
No cyst
form
Trichomonas vaginalis
• Transmission :sexual intercourse or
contact with contaminated objects.
• Pathology:
• Female: vaginitis ,profuse thin yellowish
discharge with bad smell.
• Male : invasion of urethra ,prostate
and seminal vesicles ,causing urethritis
but mostly asymptomatic.
• Diagnosis :
identification of parasites by microscopy
of discharge.
(Examination of vaginal or uretheral
discharge for T.vaginalis).
• N.B. No cyst stage
Imp
Cryptosporidium parvum
Cryptosporidiosis
zoonosis,cosmopolitan,most human and
animals infected by Cryptosporidium .
Life cycle
• Infective stage : oocyst
with4sporozoites passed in feces.
• Upon ingestion sporozoites are released.
• Sporozoite penetrate intestinal epithelial
cells and undergo two cycle :
1-schizogony
2-gametogony.
• Sporulated oocyst ,4-5M (with 4
sporozoites) are passed in feces.
duodenal biopsy sample from a patient
with AIDS and cryptosporidiosis
Pathology & clinical picture:
• Immunocopetent persons asymptomatic
or mild enterocolitis ,last about 2
weeks.
• Immunodeficient persons sever
diarrhoea with malabsorption.
Diagnosis & morphology:
• duodinal biopsy :gametes or schizont
(4-8 merozoites) in epithelial cells.
• Stools :oocyst 4-5 m with 4
sporozoites (without sporocyst).
• Treatment
- Self limited in immunocomptant
persons ,no effective drugs in cases
of AIDS.
- Management of fluid and electrolytes
loss.
• Prevention and control:
-person-to person or animal to person
transmission controlled by sanitation.
-Identify common sources e.g.
contaminated water