PROTOZOANS: AMOEBAS

Amebas move by extending their cytoplasm to form pseudopods, “false feet”, which allow them to crawl or transfer from one place to another. Most of them infect the intestines, while a few can reach the brain.

Entamoeba histolytica

The only one of the intestinal amebas, ___________, that may produce characteristic symptoms and is universally considered to be a pathogen

Pathogenic

Pathogenic or Non pathogenic: Entamoeba histolytica

Entamoeba histolytica

Protozoa that causes amebic dysentery (intestinal infection causing diarrhea and vomiting) and Amebic abscess (pus-filled mass in the liver)

Entamoeba histolytica; Trophozoites

The parasite _________ causes internal organs to have an abscess, especially the liver. The cause is the stage ________, which would invade the intestinal wall and enter the bloodstream, spreading to other organs.

Trophozoite

Protozoal stage, which is the active, feeding, multiplying stage (like a moving amoeba), where active trophozoites are often found in diarrhea. It is the PATHOGENIC stage causing symptoms.

Cysts

Protozoal stage, which is a dormant, protective stage with a tough wall, allowing survival outside the host and transmission, often found in formed feces. It is the INFECTIVE stage for transmission

Entamoeba histolytica

Worldwide, a leading cause of parasitic death

Cysts

infective form of Entamoeba histolytica

cysts or trophozoites; abscess; sigmoidoscopy

Diagnostic stage of Entamoeba histolytica are ________ in stool, amoebic _____ fluid or ______ specimen

Entamoeba histolytica

Protozoa Cysts:

• Round

• One to four Nuclei

• Central Karyosome

• Fine and even peripheral chromatin

• Rounded Chromatid bar

Entamoeba histolytica

Protozoa Trophozoite:

• Rapid and directional motion using the pseudopodia

• One nucleus with a central karyosome

• Actively feeds on host tissue, causing intestinal damage and symptoms such as dysentery

Entamoeba histolytica

Its trophozoite ingests red blood cells (RBCs), which are diagnostic—a pathognomonic for _________ infections

iodine crystals; chlorination

To prevent Entamoeba histolytica infections, boiling or treating water with _______ is essential. This is because infective cyst is resistant to routine _______ despite it being the most common way of treating water.

paromomycin or iodoquinol

For asymptomatic infections of Entamoeba histolytica, what is the drug of choice that would eliminate luminal cysts and prevent transmission

metronidazole or tinidazole

For symptomatic intestinal disease or extraintestinal infections of Entamoeba histolytica (e.g., hepatic abscess), what is the drug of choice?

paromomycin or iodoquinol

In symptomatic intestinal disease or extraintestinal infectionsof Entamoeba histolytica, the drug of choices are metronidazole or tinidazole. This is immediately followed by treatment with ____________ to eradicate residual cysts in the intestine and is used for conditions such as dysentery or liver abscess.

Non-pathogenic

Pathogenic/Non-pathogenic: Entamoeba colli

Commensal; in human intestines

What relationship does Entamoeba coli have with its hosts, and where does it live in humans?

Cysts or trophozoites in stool

Diagnostic stage of Entamoeba coli

Entamoeba coli

Protozoa Cysts:

• Round

• One to Eight Nuclei

• Eccentric Karyosome (off-centered)

• Uneven peripheral chromatin

• Splintered end chromatid bar

fecal-oral

Infective cysts form of Entamoeba coli is transmitted via the _______ route, but generally non-pathogenic

Entamoeba coli

Protozoa Trophozoite:

• Slow motility and sluggish movement with the use of the pseudopodia

• One nucleus

• Eccentric karyosome

• Coarse granular cytoplasm

Commensal

What relationship does Endolimax nana have with its hosts?

Non-pathogenic

Pathogenic/Non-pathogenic: Endolimax nana

Endolimax nana

Protozoa Cysts:

• Round to oval

• One to four nuclei

• Blot-like karyosome

• No chromatoid bodies

• Poorly defined glycogen mass

Endolimax nana

Protozoa Trophozoite:

• Single Nucleus

• Finely granular vacuolated cytoplasm

• Blunt pseudopods

• Sluggish, non-progressive motility; moves slowly without directional migration

Cysts or trophozoites in stool

Diagnostic stage of Endolimax nana

Commensal

What relationship does Iodamoeba butschlii have with its hosts?

Non-pathogenic

Pathogenic/Non-pathogenic: Iodamoeba butschlii

Cysts or trophozoites in stool

Diagnostic stage of Iodamoeba butschlii

Iodamoeba butschlii

Protozoa Cysts:

• Ovoid

• One nucleus

• Prominent glycogen vacuole

glycogen mass

Due to Iodamoeba butschlii’s __________, it typically picks up the iodine stain and is thus characteristically recognizable

Iodamoeba butschlii’s

Protozoa Trophozoite:

• Coarsely granular cytoplasm

• With vacuoles and bacteria

• Blunt pseudopod

• Sluggishly progressive motility

Naegleria fowleri

A pathogenic free-living amoeba.

Naegleria fowleri

Causes Primary amoebic meningoencephalitis (PAM), which is characterized by stiff neck, headaches, seizures, ACUTE and can progress RAPIDLY and is often fatal.

up into your nose

You CANNOT get infected from drinking water contaminated with Naegleria; you can only be infected when contaminated water goes _________

CSF, in brain tissue, or at autopsy

Trophozoites of Naegleria fowleri and Acanthamoeba spp. invade the nasal mucosa and travel to the ______, _____, or at ______.

Naegleria fowleri and Acanthamoeba spp.

Environmental organisms that enter the nasal passages, then the bloodstream to the CNS. It can be acquired by swimming in ponds, lakes during warm months.

Naegleria fowleri

Protozoa Trophozoite:

• One nucleus

• Slow motility due to amoeboid motion in the CNS tissue.

Pathogenic

Pathogenic/Non-pathogenic: Naegleria fowleri

Pathogenic

Pathogenic/Non-pathogenic: Acanthamoeba spp.

Acanthamoeba spp.

Causes Granulomatous amoebic encephalitis (GAE), which is CHRONIC, progresses SLOWLY. It is characterized by stiff neck, headaches, seizures, can progress slowly to rapidly fatal.

Keratitis

Unlike Naegleria fowleri, Acanthamoeba spp. is typically associated with eye involvement, contact lens fluid contamination, leading to _________

cornea

Acanthamoeba spp. can cause Acanthamoeba keratitis, a serious eye infection that affects the _____. It commonly occurs in contact lens users, especially when lenses are cleaned or stored improperly.

Acanthamoeba spp.

Protozoa Cysts:

• A double cell wall would provide resistance to harsh environmental conditions.

• One nucleus

• Usually dormant

Acanthamoeba spp.

Protozoa Trophozoite:

• One Nucleus

• Slow amoeboid motility

• One responsible for GAE and keratitis