溶组织内阿米巴溶组织内阿米巴

前言 前言

形态 形态

生活史

生活史

致病

致病

实验诊断

实验诊断

流行与防治

流行与防治

溶组织内阿米巴溶组织内阿米巴 Entamoeba histolyticaEntamoeba histolytica

山东大学寄生虫学教研室山东大学寄生虫学教研室 何深一何深一

IntroductionIntroduction

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 histolyticaEntamoeba histolyticaEntamoeba disparEntamoeba dispar

Major pathogen– world-wide distribution (10%)– 5% in some developed countries– 100 deaths in Chicago 1930

Trophozoite & Cyst– oral-faecal transmission

MorphologyMorphology

Pay your attention to stages that have diagnostic valueParasites stained with hematoxylin is described here.

Trophozoite (active form)Trophozoite (active form)

(1) Size: 10-40 micrometers in diameter, some a(1) Size: 10-40 micrometers in diameter, some are above 60 micrometers.re above 60 micrometers.

(2) Pseudopodium(ectopalsmic protrusion):(2) Pseudopodium(ectopalsmic protrusion):    A. broad or finger-like in form    A. broad or finger-like in form    B. thrust out quickly    B. thrust out quickly    C. firstly, formed with ectoplasm, secondly,     C. firstly, formed with ectoplasm, secondly, endoplasm flows slowly into it.endoplasm flows slowly into it.    D. motility is progressive and directional.    D. motility is progressive and directional.

Trophozoite (active form)Trophozoite (active form)

(3) Endoplasm: red blood cells may be found in (3) Endoplasm: red blood cells may be found in it.it. (4) Nucleus (vesicular type)(4) Nucleus (vesicular type)

      It is not visible in an unstained specimen;       It is not visible in an unstained specimen; but its clear structure can be seen when but its clear structure can be seen when stained with hematoxylin.stained with hematoxylin.

  A: membrane: distinct line  A: membrane: distinct line  B: chromatin granules: fine and uniformly   B: chromatin granules: fine and uniformly

arranged in the inner surface of the arranged in the inner surface of the nuclear membrane.nuclear membrane.

  C: karyosome: small and centrally located.  C: karyosome: small and centrally located.

Phase contrast photomicrograph of cultured Phase contrast photomicrograph of cultured

Entamoeba histolytica trophozoites. Entamoeba histolytica trophozoites. 

Charcot Leyden CrystalCharcot Leyden Crystal These diamond shaped

crystals are often seen in amoebic dysentery faeces and may also be present in other parasitic infections. They are absent in bacillary dysentery. Interference contrast. ×400. Enlarged by 9.6

Movement of Movement of E. histolyticaE. histolytica 进行性和定向阿米巴运动

progressive and directionalprogressive and directional

Cyst (non-motile)Cyst (non-motile)

(1) 10-20 mocrometers in size (2) spherical in shape (3) 1-2 nuclei (immature cyst); 4 nuclei (mature cy

st-infective stage). (4) inclusions:(become smaller and smaller as the

cyst ages)      glycogen vacuole  appears as a clear space; food reservoir    chromatoid body  dark blue rods or dots; its function is not known

The single nucleus with its central endosome and regularly distributed chromatin is visible.  The dark "rods" in the cytoplasm are the chromatoid bars; approximate size = 18 µm.

This is a mature cyst and contains four nuclei.  However, only two nuclei are visible in this plane of focus, and a chromatoid bar is still present; approximate size = 17 µm.

Entamoeba coliEntamoeba coli

Gut commensalTrophozoite & cystSlow “lazy” movementOral-faecal transmission

E. histolytica v E. coliE. histolytica v E. coli

Trophozoite– 10-40um– delicate nuclear

structure

Cyst– 9.5-15.5um– 4 nuclei– Broad, blunt chromatid

bodies

– 15-30um– coarse nuclear

structure

– 10-30um– 8 nuclei– thin, sharp chromatid

bodies

Entamoeba coliEntamoeba coli

             

                                                                                 

Entamoeba coliEntamoeba coli

Life CycleLife Cycle

1  infective stage: mature cyst2  access:  mouth3  ecological niches:  large intestine; liver, l

ung and other organs.4  pathogenic stage:  trophozoite5  diagnostic stage:  cyst; trophozoites

Pathogenic factorsPathogenic factors

1. Toxicity of parasites  pathogenic-

nonpathogenic complex.     Entamoeba histolytica

    Entamoeba dispar2. Symbiotic bacteria3. Defence barrier  immunity

This protein forms ion channels in lipid cell membranes and results in cell death within minutes of cell contact with the ameba. Amoebapore has been isolated, synthesized and well characterized. Non-pathogenic strains of E. histolytica can also produce amoebapore but are much less efficient at its production and the molecule is not exactly similar to that produced by virulent strains.

This cytolytic event is a result of incorporation in the host cell membrane of an ameba-produced, pore-forming protein, Amoebapore.

Pathology and Pathology and Clinical ManifestationClinical Manifestation

Pinpoint lesion on mucous membraneFlask-shaped crateriform ulcers

Clinical classificationClinical classification

Asymptomatic infection (carrier)  >90% cases (E. dispar?)

Sympomatic cases <10%– 8-10% dysentery, colitis, etc– 2% invasive amoebiasis– 0.1% deaths

A. Intestinal amoebiasisA. Intestinal amoebiasis

  a. dysentery:a. dysentery: dysenteric stools (pus and blood without feces). fever, dehydration, and electrolyte abnormalities. Tenesmus and abdominal tenderness.

  b. non-dysenteric colitisb. non-dysenteric colitis   c. appendicitisc. appendicitis   d. amoeboma:d. amoeboma:may become the leading point of may become the leading point of

an intussusception or may cause intestinal obstan intussusception or may cause intestinal obstruction. ruction.

Histopathology of a typical flask-shapHistopathology of a typical flask-shaped ulcer of intestinal amebiasis ed ulcer of intestinal amebiasis

A Micro Abscess in the submucA Micro Abscess in the submucosa .osa .

Containing a large number of E. histolytica trophozoites mostly at the periphery .H and E. ×400. Enlarged by 5.4.

B. Extra-intestinal amoebiasB. Extra-intestinal amoebiasisis

  a. Hepatic      (1) acute non-suppurative     (2) liver abscess: right upper quadrant pa

in, referred to the right shoulder. tender.   b. Pulmonary

B. Extra-intestinal amoebiasB. Extra-intestinal amoebiasisis

  c. Brain   d. Skin, perianal infection   e. Other extra-intestinal amoebiasis

Amoebic Liver AbscessAmoebic Liver Abscess

Gross pathology of liver containing Gross pathology of liver containing

amebic abscessamebic abscess

Gross pathology of amebic abscess of liver. Tube of Gross pathology of amebic abscess of liver. Tube of "chocolate" pus from abscess. "chocolate" pus from abscess.

An Amoebic Liver Abscess An Amoebic Liver Abscess Being Aspirated.Being Aspirated.

Note the reddish brown color of the pus (‘anchovy-sauce’). This color is due to the breakdown of liver cells. Enlarged by 5.4

X-ray of a Large Amoebic Liver X-ray of a Large Amoebic Liver Abscess.Abscess.

A fluid level has formed after aspiration due to entry of air

DiagnosisDiagnosis1.1.Stool examinationStool examination

trophozoite cyst

specimenfeces feces

method direct smear with normal saline

direct smear with iodine stain

diseases amoebic dysenterychronic intestinal amoebiasis or carriers

remarks

1.container must clean2.examined soon after they have been passed.3.select bloody and mucous portion.

4.keep specimen warm.

5.drug using histry. 　

DiagnosisDiagnosis

2. Serologic studies: indirect hemagglutination, skin tests, ELISA and latex agglutination.

3. Tissue examination: sigmoidoscopic biopsy, aspiration

4. DNA probe

EpidemiologyEpidemiology

Distribution:  all climates, arctic to tropical. Media:  flies; black beetles etc.

Treatment and PreventionTreatment and Prevention

Treatment:Treatment:Diodoquin-carriersMetronidazole-dysentery, liver abscess

PreventionPrevention

Human feces should not be used as fertilizerFood and drinks must be protected from

fliesPersonal hygiene:  wash hands after

defecation and before meals.