Micro444 Parasite Life Cycles

Front 1

Describe the life cycle of Entamoeba histolytica.

Back 1

cyst ingestion --> excystation in small intestine --> trophs to colon --> binary fission or cyst formation

cysts passed in feces; cycle repeats.

Front 2

When are immunoassays particularly valuable for diagnosis of an E. histolytica infection?

Back 2

for extraintestinal amoebiasis. trophs/cysts frequently not found in stool.

Front 3

Describe the life cycle of Dientamoeba fragilis.

Back 3

trophs ingested --> binary fission in colon --> trophs passed in feces.

possible transmission via helminth eggs??

Front 4

Describe the proposed life cycle of Blastocystis hominis.

Back 4

thick walled cyst ingested --> excystation of vacuolar form

vacuolar form --> asexual, amoeboid, or multivacuolar forms.

Front 5

What happens to the amoeboid reproductive form of Blastocystis hominis?

Back 5

amoeboid --> pre-cyst --> thick-walled cyst that gets passed in feces or releases vacuolar forms

Front 6

What happens to the vacuolar reproductive form of Blastocystis hominis?

Back 6

vacuolar form reproduces asexually via mitosis.

Front 7

What happens to the multivacuolar reproductive form of Blastocystis hominis?

Back 7

multivacuolar --> pre-cyst --> thin-walled cyst --> excystation of more vacuolar forms.

Front 8

Describe the life cycle of Acanthamoeba spp.

Back 8

alternates between cyst/troph in the wild

troph enters human host and wreaks havoc.

OR cyst enters human, excysts, and then wreaks havoc.

Front 9

Describe the life cycle of Naegleria fowleri.

Back 9

flagellate <--troph --> cyst
||
more trophs via promitosis

troph enters nasal mucosa of humans messing around in water and infects their brains by going up the olfactory nerve.

Front 10

Describe the life cycle of Balamutha mandrillaris.

Back 10

troph <---> cyst in the wild

troph or cyst enters human, divides by mitosis --> granulomatous amoebic encephalitis, etc.

Front 11

Describe the life cycle of Balantidium coli.

Back 11

human eats cyst --> excystation in small intestine --> trophs replicate w/mitosis, invade colon --> make more cysts --> cyst passed in feces

Front 12

Describe the life cycle of Giardia lamblia.

Back 12

ingest cyst --> cyst produces TWO trophs via excystation in small intestine --> longitudinal binary fission in small intestine --> cyst formation as they reach colon --> cysts passed in feces.

Front 13

Describe the Human life cycle of Trypanosoma brucei.

Back 13

Tryp enters via tsetse fly bite --> metacyclic trypomastigotes convert to bloodstream TM's --> TM's do binary fission in body fluids, incl. blood

TM's enter tsetse fly when it bites human and sucks blood.

Front 14

Describe Tsetse fly life cycle of Trypanosoma brucei.

Back 14

Tsetse fly ingests bloodstream trypomastigotes --> TM's convert to procyclic TM's in midgut and do binary fission --> leave midgut and convert to epimastigotes --> enter salivary gland, multiply as metacyclic TM's

B(loodstream) --> P(rocyclic) --> E(pimastigotes) --> M(etacyclic)

Front 15

Describe the life cycle of Trichomonas vaginalis.

Back 15

No cyst form--only trophs

flagellate form lives in vaginal/urinary tract of man/woman and is transmitted sexually

Front 16

Trypomastigote stage morphology?

Back 16

posterior kinetoplast

flagellum arises from kinetoplast, attached to body via undulating membrane along whole body length

Front 17

Epimastigote stage morphology?

Back 17

kinetoplast located anterior to nucleus

flagellum/membrane assemblage runs along half of body length only.

Front 18

Amastigote stage morphology?

Back 18

rounded cell shape

no flagellum or undulating membrane.

often intracellular.

Front 19

When do intestinal flagellates typically form cysts?

Back 19

As they pass further down the gastrointestinal tract (usually around when they reach large intestine).

Front 20

Describe the general life cycle of trypanosomes.

Back 20

trypomastigotes in human bloodstream, enter tsetse fly via blood meal

trypomastigotes convert to epimastigotes and multiply like crazy in tsetse fly

mature into infective metacyclic trypomastigotes, get transmitted to human.

Front 21

What is the infectious form of trypanosoma brucei that gets injected into the human host?

Back 21

metacyclic trypomastigotes.

Front 22

What form of T. brucei is found in the blood of the human host?

Back 22

dividing trypomastigote.

Front 23

What are the host preferences of T. brucei rhodesiense and gambiense?

Back 23

gambiense: anthropophilic

rhodesiense: zoophilic (more virulent)

Front 24

What is the natural reservoir of T. brucei?

Back 24

gambiense: man

rhodesiense: animals, esp. cattle, bushbuck, hartebeest

Front 25

Describe the life cycle of Trypanosoma cruzi.

Back 25

bug: trypomastigote --> epimastigote --> metacyclic trypomastigote in feces!

human: metacyclic trypomastigote --> INTRACELLULAR amastigote in heart, brain --> trypomastigotes

Front 26

What is the preferred immune escape system of T. brucei?

Back 26

surface antigen switching

Front 27

What is the preferred immune escape system of T. cruzi?

Back 27

amastigotes invade heart muscle, brain cells, esophagus, large intestine

Front 28

What is the natural reservoir of T. cruzi?

Back 28

>100 different animals! impossible to eradicate.