A. Haghighi,

Entamoeba histolytica/E. dispar

Tuesday, March 05, 2019

Classification of Protozoa ?

• The protozoa are generally unicellular and may

be divided for convenience, into four distinct

groups based on method of locomotion:

1. Mastigophora (Flagella)/Metamonada

2. Sarcodina (Pseudophora)/ Amoebazoa

3. Apicomplexa (microtubule complex)

4. Ciliophora (Ciliates)

حرکت

Human species of

Amoebae

The important intestinal amoeba in human

Phylum: Sarcomastigophora / AmoebazoaGenus: 1- Entamoeba

Species: - Entamoeba histolytica

- Entamoeba dispar

- Entamoeba moshkovskii

- Entamoeba coli

- Entaomeba hartmanni

- Entamoeba gingivalis

Genus: 2- Endolimax

Species: Endolimax nana

Genus: 3- IodamoebaSpecies: Iodamoeba butschlii

Classification based on number of nuclei in the mature cyst:

1. Octonucleate cyst group:

- E. coli

2. Quadrinucleate cyst group:

- E. histolytica

- E. dispar

- E. hartmanni

- E. moshkovskii

- Endolimax nana

3. Uninucleate cyst group:

- Iodamoeba buetschlii

4. No cyst

- E. gingivalis

General characteristics of amoebas

1- Active form (Trophozoite) has no cell wall

2- The cytoplasm of active form consists of two parts,

Ectoplasm and Endoplasmic

3- Movement is performed by forming a pseudopod in the active form

Amoeba = Variable

4- There is no particular way to get food (No mouth)

5- They do not have a fixed shape, because they create pseudopod for

locomotion and to get food.

6- They are Anaerobic, Therefore, Lack of mitochondria, endoplasmic

network and Golgi apparatus. (New molecular findings suggest traces of

these organelles)

Entamoeba histolytica<< HISTORY>>

• 1875 Fedor Aleksandrovich Losch Amoeba coli

• 1903 Fritz Schaudinn Entamoeba histolytica

• 1925 Emile Brumpt E. dysenteriae (Craig 1905)

• 1912 Von Prowazek

• 1957, 1959 Burrows

• 1973 Martinez-Palomo

• 1978-1988 Peter Sargeant and …

• 1993 Louis Diamond & C.G. Clark

• 1997 WHO meeting in Mexicocity

E. dispar (= different)

Small Race (E. hartmanni)

E. histolytica pathogen E. histolytica nonpathogen

Two species?

E. histolyticaE. dispar

E. dispar (= different)

E. histolytica

E. histolytica/E. disbar prevalence(Schoudinn 1903/ Brumt 1925)

10% of world population(about 500-700 millions)

10% E. histolytica(50-70,000,000)

90% E. dispar(450-650,000,000)<Non pathogen>

ThereforeOnly 1% of world population

Infected with E. histolytica(Amebiasis)

5-10% (5-7,000,000)

With symptoms

90-95%45-65,000,000asymptomaticCyst passers

5-7,000,000Intestinal and Extra intestinal

Amebiasis

45 - 65,000,000Cyst passers

?

About 10% (700,000)Extra intestinalAmebiasis

About 90%(4.500,000-6.500,000)Intestinal amebiasis

* Up to 100,000 deaths, second after malaria in protozoan parasites

NoTreatment

20 to 30% inthe tropics area

And 5%in temperatureclimate nations

Great geographical virulence and symptomes in the world, ranging from 1% in Greece to 21% in Egypt, average 10% of infected patients)

Transmission routes.1Feces (Person to person by the oro-fecal route)

.2Finger

.3Food

.4Fluid (Water)

.5Flies

Trophozoit Cyst

Agent of transmission

E. histolytica and E. dispar<< Morphology and life cycle>>

Large intestine

Brain

Liver

Lung

15-60 m

Trophozoite (Haematophge)

Metacysticdevelopment

Encystation

Cyst

Ch. body

Cell wall

Nucleus

Endoplasm

Ectoplasm

Karyosome

Oral infection

(10-20m)

Clumps of glycogen

Galactose/N-acetylgalactoseamine(Gal/GalNAc) lectin protein

Trophozoite

Pathogenicity

A- (Intestinal diseases) or

<< Intestinal amoebiasis>>

B- (Extraintestinal diseases)

<< Extraintestinal amoebiasis>>

Intestinal amoebiasis ?• Asymptomatic infection

• Symptomatic noninvasive infection

• Acute rectocolitis (dysentery)

• Fulminant colitis with perforation

• Ameboma

• Chronic nondysenteric colitis

• Perianal ulceration Flask form ulcers

Familiarity with these diverse manifestations and epidemiologic risk factors greatly facilitatesA rapid , correct diagnosis

Frequently:- Anti-amoebic Ab is +- and Stool Ag test is +

Diarrhea, Dysentery, weight loss, fever, tenterness, Heme +

Extraintestinal amoebiasis ?

• Amoebic Liver Abscess (ALA)

• Lung abscess

• Brain abscess

• Splenic abscess

• Subdiaphragmatic

• .Large intestine ab

• Amebiasis cutis

• Genitourinary abscess

Brain

Liver

Lung

Diagnosis methods• Intesinal amoebiasis

• Extraintestinal amoebiasis

1- Doctor: Pay attention to clinical findings, geographical location,history of illness and findings Epidemiologic

2- Parasitological methods: Detection of trophozoite or cysts in feces or abscesses by:

- Wet mount stool exam- Stool concentration (Formalin-ether technique)

(Three alternate stool tests are recommended)

Cultivation Staining

Based on :

3. Serologically tests:

* IFA

* ELISA (Sensitive tests)

* IHA

* CIE or GD : Non sensitive for acute diseases

* Antigen capture (TechLab)

4. Bichemical or Biological methods:

- PCR

- Zymoden analysis

Diagnosis of amebic liver abscess

Cinical symptoms

Positive amebic serology

*****

Lesion in the liver

WHO News and activities

Bulletin of the WHO, 1997, 75

(3); 291-292

Medical recommendation for

diagnosis and treatment

When diagnosis is made by light microscopy,

the cysts of two species (10-20 um in diameter)

are indistinguishable and should be reported

as:

E. histolytica/E. dispar

Trophozoites with ingested red blood cells in

fresh stool or other specimens and

trophozoites in tissue biopsies are both

strongly correlated with the presence of

E. histolytica and invasive disease.

In symptyomatic individuals the presence of

high titers of specific antibody is also

strongly correlated with invasive

amoebiasis.

Optimally, E. histolytica should be

specifically identified, and

infections, if present, treated is

recommended.

If only E. dispar is identified, no treatment is

necessary. If the infected individual has

gastrointestinal symptoms, other causes

should be sought.

If E. histolytica/E. dispar has been detected in

symptomatic patients, it should not be assumed

that E. histolytica is the cause of symptoms and

other explanations should also be considered.

• There are two classes of antiamoebic drugs:

a) Tissue amoebicies (Such as 5-nitoimidazole; e.g. Metronidazole)

b) and luminal amoebicides (such as diloxanide furoate and

paromomaycine).

Invasive disease should be treated with a tissue amoebiside

followed by a luminal amoebicide. Tissue amoebicides are not

appropriate for treatment of asymptomatic individuals, unless

there is other evidence for invasive amoebiasis.

• Chemoprophylaxis is never appropriate.

Treatment

24

A: In E. histolytica cyst passers

(Asymptomatic intestinal colonization)

B: Invasive rectocolitis

(Amoebic colitis)

C- Extraintesinal diseases

(Amoebic liver abscess)

Luminal agents :

Diloxanide furoate

Paromomycine

Iodoquinol

Tissue agents : Bowel wall only- Tetracycline-ErythromycineAll tissues-Metronidazile-Tinidazole-Emetine hydrochloride-Dehydroemetine

Treatment

A: In E. histolytica cyst passers

1. Diloxanid foroate

- 500 mg orally 3 times a day for 10 days

2 . Paromomycine

- 30 mg/kg/days in 3 divided doses for 5-10 days

3. Tetracycline

- 250 mg qid for 10 days then Iodoquinol, 650 mg tid for 20 days

4. Metronidazol

- 750 mg tid for 10 days.

B: Invasive rectocolitis

1. Metronidasol

2. Tetracycline,

3. Dehydroemetine

C- Extraintesinalis treatment1. Metronidasol

2. Tinidazol

3. Dehydroemetine

Treatment should be follow with one of the effective

medicines on the cyst

Prevention

1- Individual health (hand wash with soap, Destroying the flies and

cockroaches, Using healthy food and especially vegetables)

2- Public Health (Proper disposal of waste, Environmental improvement,

Health improvement, Proper disposal of sewage)

3- Health Education (Use of Mothers' Breastfeeds, Health Education

in Schools, Health education through radio and television)

Vaccination: Researching on 3 genes