Amoeba + Flagellates + Intestinal Ciliate + Intestinal Coccidia

What are protozoa

They are eukaryotic, unicellular organisms that divide by binary fission and can be found worldwide

What are the four groups of protozoa?

1. Amoebae

2. Flagellates

3. Ciliates

4. Coccidia

What is the function of pseudopods in amoebae?

They help them move and capture food

How do flagellates move?

Move using one or more whip like structures called flagella

What are cilia, and which group of protozoa has them?

They are short, hair like structures that help in movement, they are found on ciliates

What are the two developmental stages of most protozoa?

Cyst and Trophozoites

What is the cyst form of protozoa?

It is rigid, non-motile, and found in formed stools. It is the infectious form and is resistant to environmental changes

What does the presence of cysts usually indicate?

Inactive infection or a carrier state

What is the trophozoite form of protozoa?

It is motile, found in watery or unformed stool, and is the feeding form associated with active disease

Why is the trophozoite form sensitive to environmental changes?

Because it is not protected by a rigid wall, making it vulnerable to temperature and other environmental factors

What is excystation?

The process where the cyst form transforms into the trophozoite form after being ingested by the hos

Where are intestinal amoebae typically found?

In the intestinal tract and include both free living and parasitic organisms, which can be either pathogenic or nonpathogenic

What disease does Entamoeba histolytica cause?

Amoebic dysentery

What is the most frequent route of Entamoeba histolytica transmission to humans?

Contaminated food or water with stool containing cysts

After ingestion, in which part of the digestive system does excystation of Entamoeba histolytica occur?

In the small intestine

How many trophozoites are formed from a single cyst of Entamoeba histolytica?

8 small trophozoites

What method of reproduction do Entamoeba histolytica trophozoites use to multiply?

Binary fission

What transformation do Entamoeba histolytica trophozoites undergo before being excreted in feces?

They encyst and then are passed in the feces in formed or semisolid stools

Does the life cycle of Entamoeba histolytica involve another animal host besides humans?

No

Can individuals infected with Entamoeba histolytica have no symptoms?

Yes

What symptoms are common in people with acute amoebic dysentery (Entamoeba Histolytica)

1. Abdominal pain and tenderness

2. Cramping

3. Anorexia

4. Weight loss

5. Bloody diarrhea

How can Entamoeba histolytica trophozoites cause extraintestinal complications?

They can spread through the blood or lymphatic vessels to the liver, lungs, and brain causing extraintestinal amoebiasis

What may be found in the intestinal tract of someone with chronic amoebic dysentery?

Amoebic granulomas along with shedding of intestinal mucosa in the stool

How is intestinal amoebiasis typically diagnosed in the lab?

By identifying the cyst or trophozoite stage in a stool specimen

What features help identify E. histolytica trophozoites in a stool sample?

They show progressive directional motility and may contain ingested red blood cells

What are distinguishing features of E. histolytica cysts?

The cysts contain one to four nuclei and cigar shaped chromatoidal bodies

Does finding cysts of E. histolytica in the stool always indicate active disease?

No

What are Charcot-Leyden crystals, and where might they be found?

They are degenerating eosinophils, found in the stools of various parasitic infections including amoebic dysentery

Where is Entamoeba gingivalis found, and is it harmful?

It is non-pathogenic and found in the gingival pockets of the human oral cavity

How can Iodamoeba butschlii be identified in its cyst form?

It can be characterized by a large glycogen mass, which appears reddish brown with iodine stain in the cyst form

How many nuclei are typically found in a mature Entamoeba histolytica cyst?

2-4

Describe the karyosome and chromatin pattern of Entamoeba histolytica cysts.

Small, central karosome with fine, peripheral, beaded chromatin

What type of chromatoidal bodies are found in Entamoeba histolytica cysts?

Cigar shaped with smooth, rounded edges

How many nuclei can be seen in a mature Entamoeba coli cyst?

2-8

What distinguishes the chromatoidal bodies in Entamoeba coli cysts?

Slender, splinter shaped bodies with rough pointed ends

How is the karyosome of Entamoeba coli described?

Large, compact, and eccentric

What is a key identifying feature of Endolimax nana cysts?

No peripheral chromatin

How many nuclei are present in mature Endolimax nana cysts?

1-4

Are chromatoidal bodies seen in Endolimax nana cysts?

No

How many nuclei are typically found in Iodamoeba butschlii cysts?

Usually one, occasionally two

What are the characteristics of the karyosome in Iodamoeba butschlii cysts?

Large and eccentric, surronded by retractile granules

Is Entamoeba histolytica pathogenic or nonpathogenic?

Pathogenic

What is the pathogenicity of Entamoeba coli?

Commensal (nonpathogenic)

What is the pathogenicity of Endolimax nana?

Commensal (nonpathogenic)

Is Iodamoeba butschlii considered pathogenic?

Commensal (nonpathogenic)

What is a key diagnostic feature of Entamoeba histolytica trophozoites under the microscope?

Presence of ingested RBCs

What are the nucleus and karyosome characteristics of Entamoeba histolytica trophozoites?

Single nucleus with a small, compact, central karyosome; fine, evenly distributed or beaded peripheral chromatin

What size range and cytoplasmic appearance does the Entamoeba histolytica trophozoite exhibit?

It is 10-60 um with a finely granular cytoplasm with a “ground glass” appearance, ectoplasm, and endoplasm are well defined

What is the size and cytoplasm description of the Entamoeba coli trophozoite?

15-50 um with coarsely granular and vacuolated cytoplasm, often appearing junky

What nuclear features distinguish Entamoeba coli trophozoites?

A single nucleus with a large, eccentric karysome and coarse, irregular peipheral chromatin

What is the size and cytoplasmic appearance of Endolimax nana trophozoites?

6-12 um with granular, vacuolated cytoplasm

What are the nuclear features of Endolimax nana trophozoites?

Large, lobulated nucleus with a large, prominent karosyome and no peipheral chromatin

What is the size and cytoplasm description of Iodamoeba butschlii trophozoites?

10 - 20 um coarsely granular, vacuolated cytoplasm with many vacuoles

Describe the nucleus and karyosome of Iodamoeba butschlii trophozoites.

Single, large nucleus with a large, eccentric karyosome surrounded by retractile granules; no peripheral chromatin

What are the four main genera of free-living amoebae that can infect humans?

Naegleria, Acanthamoeba, Balamuthia, and Sappinia

In what types of environments are free-living amoebae typically found?

1. Water sources: Rivers, lakes, AC, humidifiers. cooling towers

2. Vegetation

3. Sewage

4. Dust

5. Air

6. Compost

How do people most commonly acquire infections with free-living amoebae?

Through direct contact with contaminated water, often while swimming in unchlorinated lakes

Besides direct water exposure, how else can free-living amoebae enter the human body?

They can be inhaled in contaminated dust or aerosols, or enter through breaks in the skin

Are free-living amoebae considered primary or opportunistic pathogens?

Opportunistic pathogens

What serious condition is caused by Acanthamoeba and Balamuthia?

Granulomatous amoebic encephalitis (GAE)

What fatal central nervous system infection is caused by Naegleria?

Primary amoebic meningoencephalitis (PAM)

Which free-living amoeba is a rare cause of encephalitis?

Sappinia

From which body sites have free-living amoebae been isolated in infected patients?

1. Lungs

2. Sinuses

3. Eyes

4. Ears

5. CSF

6. Skin lesions

How common are infections caused by free-living amoebae?

These infections are not common, but they are difficult to diagnose and often have a very high mortality rate

How is Naegleria fowleri transmitted to the human body?

It is transmitted through inhalation into the upper respiratory tract, often via contaminated water

What is the route Naegleria fowleri takes to reach the brain?

It penetrates the nasal mucosa and travels along olfactory nerves to the brain and central nervous system

What is the typical incubation period for Naegleria fowleri infection?

2 days to 2 weeks

What are the early symptoms of Primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri?

1. Fever

2. Stiff neck

3. Severe headache

4. Nausea

5. Vomiting

What neurological symptoms develop as Naegleria fowleri infection progresses?

1. Drowsiness

2. Confusion

3. Seizures

4. Coma

How quickly does Naegleria fowleri infection typically lead to death after symptoms begin?

The infection is usually fatal within 1 week of symptom onset

What are common environmental sources and activities linked to Naegleria fowleri infection?

1. Swimming in warm lakes, muddy or brackish water

2. Forceful entry of water into the sinuses (water skiing or sinus rinsing)

What is the shape and structure of Naegleria fowleri cysts?

It is hexagonal, thin walled, and lacks pores

What morphological transformation can Naegleria fowleri undergo in water?

It can transform into a pear shaped flagellate form

What is the maximum temperature Naegleria fowleri can survive?

45°C

Why is Naegleria fowleri often misdiagnosed?

Because PAM resembles bacterial meningitis, leading to delayed or missed diagnosis

What findings in cerebrospinal fluid (CSF) are associated with Naegleria fowleri infection?

1. Increased neutrophils

2. Elevated protein

3. Normal or decreased glucose

4. Presence of trophozoites w/o bacteria

How is PAM caused by Naegleria fowleri diagnosed?

By examining the CSF for trophozoites; however, diagnosis is often made only at autopsy

Which major pathogens can use Acanthamoeba as a host or reservoir?

Legionella, Vibrio cholerae, and Escherichia coli O157

What are common neurological symptoms of granulomatous amebic encephalitis (GAE) caused by Acanthamoeba?

1. Headaches

2. Stiff neck

3. Seizures

4. Mental confusion

5. Hemiparesis

6. Progressive neurological deficit that may lead to death

How long can the incubation period of Acanthamoeba infection last?

Months or even years

What skin condition can Acanthamoeba cause in infected individuals?

Granulomatous skin lesions

What eye disease can be caused by Acanthamoeba, and what triggers it?

Amoebic keratitis, caused by corneal contact with contaminated water

What are the symptoms of Acanthamoeba keratitis?

1. Blurred vison

2. Photophobia

3. Inflammation

4. Eye pain that may resemble bacterial or herpes simplex infection

Who is most at risk for developing Acanthamoeba keratitis?

People who wear soft or extended-wear contact lenses that are not properly disinfected

What kind of pseudopodia does Acanthamoeba use for movement?

Blunt pseudopods with spiny projections called acanthopodia

What structural features are seen in the cytoplasm of Acanthamoeba?

A well defined ectoplasm and endoplasm

How resistant are Acanthamoeba cysts to environmental conditions?

The cysts may be resistant to chlorination and drying

What are intestinal flagellates also known as in terms of classification?

Mastigophora

How do intestinal flagellates move?

They move using flagella, which are long extensions of cytoplasm

How does the structure of flagellates compare to that of amoebae?

They are more rigid and are able to maintain their shape better

What areas of the body can be affected by infections with flagellates?

The gastrointestinal tract, blood, and urogenital tract

What are five medically important intestinal flagellates?

• Giardia duodenalis (formerly G. lamblia)

• Trichomonas vaginalis

• Trichomonas hominis

• Chilomastix mesnili

• Dientamoeba fragilis

What disease is caused by Giardia duodenalis?

Giardiasis

How common is Giardia duodenalis in the United States?

It is the most frequently isolated protozoan in the United States

What are common sources of Giardia infection?

1. Contaminated water

2. Fecally contaminated swimming pools

3. Untreated lake or pond water

Who is most at risk for Giardia infection in the U.S.?

• Infants and children in daycare

• Campers and hikers who drink stream water

• Travelers to endemic areas

• Individuals engaging in oral-anal sex

How is Giardia duodenalis transmitted?

By ingestion of infective cysts, especially in areas of poor sanitation.

Is Giardia duodenalis considered a pathogenic protozoan?

Yes

What is the minimum infectious dose for Giardia duodenalis?

As few as 10 cysts

What part of the body does Giardia duodenalis primarily affect?

It causes inflammation of the intestinal mucosa, particularly in the small intestine