The Amoeba

Question 1

What are Ameba?

Answer 1

Single-celled parasite that moves by means of cytoplasm extensions called pseudopods (false feet)

Question 2

Trophozoite

Answer 2

Motile feeding stage of amebas that multiply by binary fission

Question 3

Cyst

Answer 3

Non-motile, non-feeding stage of amebas that are capable of survival outside their hosts and initiating human infection

Question 4

Karysome

Answer 4

Central mass of chromatin inside select amebic nuclei

Question 5

Peripheral chromatin

Answer 5

Ring of chromatin that surrounds the nuclei of select amebas

Question 6

Chromatid bar

Answer 6

Oblong structures containing condensed RNA material in the cytoplasm of amebic cysts

Question 7

Excystation

Answer 7

The transformation of amebic cysts into amebic trophozoites

Question 8

Encystation

Answer 8

The transformation of amebic trophozoites into amebic cysts

Question 9

What are the two amebic morphologic forms?

Answer 9

Trophozoites and Cysts

Question 10

What is the infective stage?

Answer 10

Ingestion of cysts in the human intestinal tract

Question 11

How do trophozoites multiply in the intestinal tract?

Answer 11

Asexual binary fission

Question 12

What is the diagnostic stage?

Answer 12

When cysts and/or trophozoites do not make the conversion in time.
- Usually found in the stool

Question 13

Can trophozoites live in outside environment?

Answer 13

No in the outside environment they disintegrate.

Question 14

Can cysts live in outside environment?

Answer 14

Yes they continue to develop in the outside world for subsequent entry into unsuspecting human.

Question 15

True or False:
Most intestinal amebic infections are asymptomatic.

Answer 15

True

Question 16

What intestinal ameba is pathogenic?

Answer 16

Entamoeba Histolytica

Question 17

What is the sample of choice for recovering intestinal amoeba?

Answer 17

Stool

Question 18

What is the sample of choice for recovering extraintestinal amoebae?

Answer 18

CSF/brain tissue or corneal scrapings.

Question 19

What are the 3 intenstinal species?

Answer 19

Entamoeba histolytica
Entamoeba hartmanni
Endolimax nana

Question 20

What are the 2 extraintestinal species?

Answer 20

Naegleria fowleri
Acanthoamoeba species

Question 21

Where can you find E. histolytica?

Answer 21

Tropic,subtropic, and cold climates.

Question 22

How is E. histolytica transmitted?

Answer 22

Via contaminated food/water, hand-to-mouth, unprotected sex (anal/oral)

Circulating flies and cockroaches.

Question 23

What are the symptoms of an E. histolytica infection?

Answer 23

Diarrhea, dysentery, abdominal pain/cramping, weight loss.

Question 24

Prevention and control of E. histolytica

Answer 24

1. Proper water treatment and food/handling preparation
2. Protected sex
3. Protection of food from insects
4. Avoidance of human stool

Question 25

Laboratory diagnosis of E. histolytica

Answer 25

1. Stool - evidence of RBCs within cytoplasm

Question 26

What are the two non-pathogenic ameba?

Answer 26

Entamoeba hartmanni and endolimax nana

Question 27

How can you disninguish E. histolytica vs. Endolimax hartmanni in diagnosis?

Answer 27

Major difference is SIZE

Question 28

Transmission for Endolimax hartmanni

Answer 28

1. Consumption of contaminated food/water 2. Via insects

Question 29

What are the two extraintestinal species of amoeba?

Answer 29

Naegleria fowleri and acanthamoeba species

Question 30

Where is Naegleria fowleri found?

Answer 30

Warm bodies of water including lakes, streams, ponds, and swimming pools and contaminated dust

Question 31

What severe disease does Naegleria fowleri cause?

Answer 31

Primary amebic meningoencephalitis (PAM) - trophozoites invade and cause rapid brain tissue destruction.

Question 32

How do you diagnose Naegleria fowleri?

Answer 32

Saline/iodine wet preps of CSF are best for ameboid trophs, tissues, or nasal discharge

Question 33

What are the 3 morphologic forms of naegleria fowleri?

Answer 33

1. Ameboid trophozoite 2. Flagellate form 3. Cyst

Question 34

True or false: Entire life cycle of N. fowleri occurs in external environment.

Answer 34

True

Question 35

What is the epidemiology of Acanthamoeba species?

Answer 35

Immunocompromised or debilitated individuals at greatest risk for CNS infections; or soft contact lens wearers.

Question 36

What is Granulomatous amebic encaphalitis (GAE)?

Answer 36

Granulomatous lesions of the brain that result in ocular pain and vision problems.

Question 37

How do humans contact Acanthamoeba species?

Answer 37

1. Aspiration or nasal inhalation of the organisms through nasal mucousa and/or skin 2. Direction invasion into the eye

Question 38

What is the reservoir for E. histolytica?

Answer 38

Humans/accidental host

Question 39

Describe the life cycle of E. histolytica in your own words.

Question 40

What is the concern with untreated infections of E.histolytica?

Answer 40

Extraintestinal mybiosis.