Other Human Amoebae Entamoeba dispar/E. hartmanni - PowerPoint Presentation

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Other Human Amoebae

Entamoeba dispar/E. hartmanni

: Non pathogenic; anatomically indistinguishable from

E. histolytica.

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Entamoeba coli

Trophozoite Cyst Nucleus

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Entamoeba coli

Life cycle and location identical to

E. histolytica

.

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Entamoeba coli

Life cycle and location identical to

E. histolytica

.

Most common endocommensal in people; has a worldwide distribution and 10-50% of the population can be infected in different parts of the world.

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Entamoeba coli

Life cycle and location identical to

E. histolytica

.

Most common endocommensal in people; has a worldwide distribution and 10-50% of the population can be infected in different parts of the world.

Not pathogenic.

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Entamoeba coli

Life cycle and location identical to

E. histolytica

.

Most common endocommensal in people; has a worldwide distribution and 10-50% of the population can be infected in different parts of the world.

Not pathogenic.

Feeds on bacteria and any other cells available to it;

does not invade tissue

.

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Other Hosts

Monkeys

Apes

Pigs

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10

m

m

Trophozoites 20-30

μ

m in diameter (15-50 µm)

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10

m

m

A

D

C

B

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10

m

m

A

D

C

B

E. coli

E. histolytica

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C

10

m

m

Cysts 10-30

μ

m

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Entamoeba gingivalis

 

Habitat: Mouth

Hosts: Humans, other primates, dogs and cats.

Prevalence is from 50 to 95%.

 

Stage: Trophozoite, no cyst.

 

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Entamoeba gingivalis

 

Trophozoite lives on the surface of teeth and gums. Feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them.

 

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Entamoeba gingivalis

 

Trophozoite lives on the surface of teeth and gums. Feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them.

Organisms are more common in persons with pyorrhea (gum disease) but they are not the cause of the condition.

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Entamoeba gingivalis

 

Trophozoite lives on the surface of teeth and gums. Feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them.

Organisms are more common in persons with pyorrhea (gum disease) but they are not the cause of the condition.

Transmission mouth to mouth, droplet spray, or sharing eating utensils.

 

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Endolimax nana

“The dwarf internal slug”

Trophozoite Cyst Nucleus

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Endolimax nana

Second most common endocommensal of humans, worldwide distribution 30%.

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Endolimax nana

Second most common endocommensal of humans, worldwide distribution 30%.

Lives in the large intestine mainly near the cecum and feed on bacteria; non pathogenic.

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Endolimax nana

Second most common endocommensal of humans, worldwide distribution 30%.

Lives in the large intestine mainly near the cecum and feed on bacteria; non pathogenic.

Also occurs in monkeys.

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10

m

m

Trophozoites are tiny 6-15

μ

m in diameter.

Large glycogen vacuoles are often present.

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10

m

m

Mature cyst is 5 – 14

μ

m in diameter; contains 4 nuclei; shape is round to elliptical

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Iodamoeba buetschlii

Trophozoite Cyst Nucleus

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Iodamoeba buetschlii

Not very common endocommensal in people.

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Iodamoeba buetschlii

Not very common endocommensal in people.

Lives in the large intestine, predominantly in the cecal areas.

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Iodamoeba buetschlii

Not very common endocommensal in people.

Lives in the large intestine, predominantly in the cecal areas.

Has a very high prevalence in

pigs

; 50% of pigs are infected with this ameba in France and Egypt; pigs are probably its normal host.

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10

m

m

Trophozoites are 9-14

μ

m long but may be as large as 20

μ

m

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10

m

m

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10

m

m

E. nana

I. buetschlii

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10

m

m

Cysts are 6-15

µm long and have a large glycogen vacuole.

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Dientamoeba fragilis

Trophozoite No Cyst Nucleus

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Dientamoeba fragilis

LIFE CYCLE - it does not form cysts and trophozoites cannot survive passage through the small intestine.

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Dientamoeba

fragilis

LIFE CYCLE - it does not form cysts and

trophozoites

cannot survive passage through the small intestine.

Humans probably get infected by this

endocommensal

when they ingest pinworm eggs!

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10

m

m

Trophozoites small 6-12

µm long; binucleated.

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free-living amoebae causing human infections

N

ormal

inhabitants of soil and water where they feed on bacteria.

A

few members have the ability to become

facultative

parasites

when an

opportunity

to enter a vertebrate exists

.

There

are able to infect humans

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Naegleria

fowleri

primary

amebic

meningoencephalitis

(PAM)

Acanthamoeba

spp.

granulomatous

amebic encephalitis (GAE)

granulomatous

skin and lung lesions (primarily

immunocompromised

)

amebic

keratitis

Balamuthia

mandullaris

.

GAE

+

granulomatous

skin and lung lesions (primarily healthy)

Pathogenic Free-Living

Amebae

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Naegleria

fowleri

Naegleria

fowleri

is a free living brain-eating amoeba.

Typically found in warm fresh water (thermo tolerant amoeba).

worldwide distribution.

It exists in

trophozoite

and cyst forms and in a transient flagellate stage

.

Naegleria

fowleri

is the causative agent of

primary amebic

meningoencephalitis

(PAM).

The period incubation is short, the symptoms are acute, and death is almost certain and rapid.

Naegleria

fowleri

invades the C.N.S. via penetration of the olfactory mucosa and nasal tissues (nose).

Since

Naegleria

fowleri

trophozoites

and cysts are susceptible to chlorine, swimming pools should be adequately chlorinated

.

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Naegleria

fowleri

Structures of the amoeba form are :

Trophozoit

and flagellate

The infective stage is

trophozoit

stage

Method of transmission is by penetrate the mucosal layer of olfactory tissue and nasal cavity

Leads to Primary amebic

meningoencephalitis

Most symptoms involving fever , headache, stiff neck and confusion.

Diagnosis with X-ray , IHAT in CSF.

Occasionally, a C.T scan may be ordered to rule out cerebral hematoma. culture media of CSF and PCR .

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low nutrients

desiccation

Naegleria

SPP.

Cyst = dormant form

Trophozoite

=

feeding and replicating form

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Naegleria

fowleri

When a victim swims or sinks into freshwater.

All

victims have had a

history of swimming

in freshwater lakes or ponds or swimming pools a few days before the onset of symptoms

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Naegleria

fowleri

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Primary Amebic

Meningoencephalitis

(PAM)

1-14 days incubation period

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, lethargy, disorientation, coma

rapid clinical course, death in 4-5 days after onset of symptoms

trophozoites

can be detected in spinal fluid, but diagnosis is usually at autopsy

4 known survivors treated with

Amphotericin

B

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brain section

in vitro culture

“lobopodia”

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Acanthamoeba

Acanthamoeba

are ubiquitous organisms in nature.

Most

species are free-living.

Cysts

are common and are very resistant to chlorine.

Some

are opportunists that can cause infections in human.

Infections

with these amoebae are more common in

immunocompromised

patients.

Amoebae

can be introduced through environmental exposures, including swimming while wearing contact lenses or using contaminated contact lens solutions.

Acanthamoeba

genus

causes 3

clinical

syndromes:

1

-

granulomatous

amebic

encephalitis

(GAE).

2

-

Disseminated

granulomatous

amebic disease

(

eg

, skin, sinus, and pulmonary infections).

3

-

Amebic

keratitis

: a sight-threatening disease. Most cases occur in people who wear contact lenses.

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Acanthamoeba

culbertsoni

Free-living

trophozoites

and cysts occur in both the soil and freshwater.

Trophozoites

occur only as amoeboid forms

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Acanthamoeba

culbertsoni

Free-living amoeba

Lives in water have been found in soil; sea water; sewage; swimming pools; contact lens equipment; medicinal pools; dental treatment units and air conditioning systems

Contact lens

wearers can get

keratitis

(infection of the cornea) by using tap water for lens disinfection or by swimming

when wearing lenses

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Acanthamoeba

life cycle

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Acanthamoeba

Meningoencephalitis

portal of entry unknown, possibly respiratory tract, eyes, skin

presumed

hematogenous

dissemination to the CNS

infection associated with debilitation or

immunosuppression

onset is insidious with headache, personality changes, slight fever

progresses to coma and death in weeks to months

amebas not yet detected in spinal fluid

trophozoites

and sometimes cysts detectable in histological examination

no human cures documented

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Acanthamoeba results in lesions of the skin, eye, brain, etc

.

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The symptoms of GAE including :

Alter mental status, headache ,fever, neck stiffness, seizures, focal neurological signs and coma leading to death

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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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keratitis

:

corneal inflammation and corneal perforation often followed by blindness.

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Laboratory Diagnosis of infections with free-living amoebae

:

Keratitis

:

Acanthamoeba

trophozoites

or cysts can be demonstrated with

corneal scrapings

or a biopsy sample via wet mount, stains,

histopathologic

examination.

Granulomatous

amebic encephalitis

: _ This condition is diagnosed via

brain biopsy

. (cyst and

trophozoit

)