Protozoa

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Protozoa Intestinal Amoeba
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• 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.

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• 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.

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• Entamoeba histolytica
• Worldwide, with higher incidence of amoebiasis in
  developing countries.
• risk groups include male homosexuals, travelers
  and recent immigrants, and institutional
• populations.

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morphology
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• 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.

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E.dispar has similar live cycle but non invasive
,not pathogenic.
Via polluted water infected food handler, flies
contaminating food, soil cultivation, direct
contact
Viability -Moist ,cool condtion Up to 12days
-In water 9-30 day
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• 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.

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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
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Complications and squeals
-Perforation hemorrhage (rare)
-Pretonitis haemorrhag
-Surronging inflammatory reaction
-Secondary infection
-A mass under oedemotous mucosa Amoeboma
clinically simulates neoplasm
Amoeboma Obestraction intusssception
-Invasion of blood vessels. -Direct extension
outside bowel
-Extraintestinal lesion
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• -Ulcer with peritonitis
• - hemorrhage
• - surrounding inflammatory reaction
• and fibroplastic proliferation a
• mass formed under edematous
• mucosa amoeboma (simulate carcinoma)

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Extra intestinal extension
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Extra intestinal extension
Liver involvement - Secondary to - Concomitant
with - Independent of
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.
A
B
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• 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. 

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C D
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erythro-phagocytosis,
e
f
Trophozoites of Entamoeba histolytica with
ingested erythrocytes .The ingested erythrocytes
appear as dark inclusions.
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• Erythro-phagocytosis
• is the only morphologic characteristic that can
  be used to differentiate E. histolytica from the
  non-pathogenic
• E. dispar

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• 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.

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MatureEntamoeba histolytica cysts usually measure
12 to 15 µm. cysts have 4 nuclei. 
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• Entamoeba coli

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Trophozoites of Entamoeba coli
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C
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• 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.

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• 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.

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Entamoeba coli cyst
E
D
F
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• Clinical FeaturesA 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).

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pinpoint lesion on mucous membrane
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flask-shaped (Ulcers)
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Amoebic abscess in liver
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• 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
•    

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• b.Extra-intestinal amoebiasis 
• a. Hepatic
• (1) acute non suppurative
• hepatitis   
• (2) liver abscess 
• b. Pulmonary 
• c. Brain, Skin, Other extra-
• intestinal amoebiasis.

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• Hepatic amoebiasis
• sing symptoms
• Local discomfort.
• Malaise, fluctuant temperature
• Toxemia.
• Pain in right shoulder.

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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)

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• 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.

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• 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. 

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• 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)

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• 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.

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FREE-LIVING PROTOZOA

• Ameba Diseases
• Naegleria fowleri
• PAM
• Acanthamoeba spp.
• GAE,
• skin or lung lesions,
• amebic keratitis.

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Acanthamoeba spp 7 species
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• 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.

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• 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.

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• 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.

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Niglaria fowleri
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Naegleria fowleri

• found in fresh water.
• ameba with loblose
• Pseudopodia.
• motile bi-flagellated form.
• PAM first recognized by
• Fowler (1965).

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• 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.

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Giardia lamblia
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• 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.

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Laboratory diagnosis -Stool examination daily
for three days. -Examination of duodenal
aspirate, or by string (enterotest)
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Trichomonas vaginalis
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No cyst form
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• 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.

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• Diagnosis
• identification of parasites by microscopy of
  discharge.
• (Examination of vaginal or uretheral discharge
  for T.vaginalis).
• N.B. No cyst stage Imp

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• Cryptosporidium parvum

Cryptosporidium pravum
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• 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.

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duodenal biopsy sample from a patient with AIDS
and cryptosporidiosis
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• 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).

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• 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

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