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BM211: Introduction to Microbiology > Block E Lecture 3: Protozoan Cell Biology and Disease - Part A - Visceral Parasitic Infections > Flashcards

Block E Lecture 3: Protozoan Cell Biology and Disease - Part A - Visceral Parasitic Infections Flashcards

A discussion of various parasites and how they can affect the human body

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Biology 101 flashcards
1
Q

What is a protozoan?

A

A single celled eukaryote belonging to the protista kingdom
(Slide 1)

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2
Q

What is Entamoeba histolytica?

A

A pathogenic protist
(Slide 5)

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3
Q

What disease does entamoeba histolytica cause?

A

Amoebiasis
(Slide 5)

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4
Q

How are amoebiasis, balantidiasis giardiasis and cryptosporidiosis primarily transmitted?

A

Through contaminated water (and contaminated food for amoebiasis)
(Slides 5, 7,8 and 12)

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5
Q

What is excystation?

A

When a parasite “hatches” from its protective cyst
(Slide 5)

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6
Q

What are the symptoms of amoebiasis, balantidiasis and cryptosporidiosis?

A

It can be asymptomatic or lead to diarrhea and / or dysentery, excystation can also lead to cysts forming in the small intestine
(Slide 5)

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7
Q

Where can entamoebas histolytica parasites occasionally invade when left untreated?

A

The liver, and sometimes even the lungs and brain
(Slide 5)

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8
Q

What can be used to treat amoebiasis, balantidiasis, giardiasis and trichomoniasis?

A

Metronidazole
(Slides 5,7,8 and 10)

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9
Q

How is amoebiasis and giardiasis diagnosed?

A

Via cysts in stool
(Slide 5)

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10
Q

What is the first stage of the lifecycle of entamoeba histolytica?

A

Mature cysts are digested by the host via contaminated food or water
(Slide 6)

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11
Q

What happens in the lifecycle of entamoeba histolytica after a host digests it’s mature cysts?

A

These cysts pass through the stomach and make their way into the small intestine
(Slide 6)

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12
Q

What happens in the lifecycle of entamoeba histolytica after digested cysts reach the small intestine?

A

The environment of the small intestine triggers excystation, where the cysts are transformed into trophozoites
(Slide 6)

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13
Q

What happens in the lifecycle of entamoeba histolytica after cysts transform into trophozoites?

A

These trophozoites can colonise the large intestine and then invade the intestinal mucosa where they can multiply and feed on host tissue
(Slide 6)

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14
Q

What happens in the life cycle of entamoeba histolytica after trophozoites invade the intestinal mucosa and feed on tissue?

A

Some can form new cysts and exit the body via faeces, leading to contamination of the environment and potential transmission to new hosts
(Slide 6)

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15
Q

What are balantidium coli?

A

Ciliated intestinal human and swine parasites
(Slide 7)

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16
Q

What disease does balantidium coli cause?

A

Balantidiasis
(Slide 7)

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17
Q

How is balantidiasis diagnosed?

A

In stool and colon tissue
(Slide 7)

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18
Q

How does the lifecycle of balantidium coli compare to that of entamoeba histolytica?

A

The main difference is that entamoeba histolytica excysts in the small intestine whereas balantidium coli excysts in the large intestine
(Slide 7)

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19
Q

What is giardia intestinalis?

A

A flagellated anaerobic parasite which has mitosomes (mitochondrial remanent organelles)
(Slide 8)

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20
Q

What disease does giardia intestinalis cause?

A

Giardiasis
(Slide 8)

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21
Q

On top of having similar symptoms to amoebiasis and balantidiasis what additional symptoms can giardiasis present itself as?

A

Intestinal cramps, nausea, weight loss and malaise (general feeling of discomfort or illness)
(Slide 8)

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22
Q

What is the main difference between the lifecycles of entamoeba histolytica and giardia intestinalis?

A

Entamoeba histolytica primarily residues in the large intestine (after excysting in the small intestine) whereas giardia intestinalis primarily colonises and eats the mucosal lining of the small intestine
(Slide 10)

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23
Q

What is trichomonas vaginalis?

A

A flagellated anaerobic parasite
(Slide 10)

24
Q

How can trichomonas vaginalis be transmitted?

A

Via sexual intercourse, or via toilet seats, sauna benches, towels etc
(Slide 10)

25
Q

What parasite causes trichomoniasis?

A

Trichomonas vaginalis
(Slide 10)

26
Q

What are the symptoms of Trichomoniasis?

A

Mainly asymptomatic in males, cause vaginal purulent discharge, itching and burning in women
(Slide 10)

27
Q

How is Trichomoniasis diagnosed?

A

Via microscopy and cell culture from patient secretions
(Slide 10)

28
Q

What occurs in the life cycle of trichomonas vaginalis?

A

Trophozoites are transmitted to the host (primarily through sexual intercourse) and reside in the lower genital tract (female) or the urethra and prostate (male) where it multiplies via binary fission. The parasite is thought to not have a cyst form and therefore doesn’t survive well in the external environment
(Slide 11)

29
Q

What is cryptosporidium parvum?

A

A protist parasite which lives in warm-blooded animals (it can use intermediate hosts)
(Slide 12)

30
Q

What disease does cryptosporidium parvum cause?

A

Cryptosporidiosis
(Slide 12)

31
Q

What does cryptosporidium parvum produce?

A

Thick-walled cells called oocysts
(Slide 12)

32
Q

What is the purpose of oocysts?

A

They are shed in the faces of infected animals so that the parasite can be transmitted via faeces contaminated water
(Slide 12)

33
Q

What 2 things are oocysts highly resistant to?

A

Chlorine and UV radiation
(Slide 12)

34
Q

Due to them being highly resistant to chlorine and UV radiation, what is the best way to remove oocysts from water?

A

Via filtration methods
(Slide 12)

35
Q

Where does the cryptosporidium parvum parasite develop?

A

Under the host intestinal tract cell’s epithelial cell membrane in an intracellular but extracytoplasmic (outside of the cytoplasm) position
(Slide 13)

36
Q

What kind of infection does cryptosporidium parvum exhibit?

A

Auto-infection (When an individual is infected by a pathogen that is already in its body)
(Slide 13)

37
Q

How is Cryptosporidiosis diagnosed?

A

In stool samples with direct fluorescence antibody assay (DFA)
(Slide 13)

38
Q

How is Cryptosporidiosis treated?

A

It is usually a self-limiting reaction though nitazoxanide can be used as it interferes with anaerobic energy metabolism
(Slide 13)

39
Q

How does cryptosporidium infect a new host?

A

Thick-walled (sporulated) oocysts are excreted by the infected hosts via faeces and a new host ingests / inhales these usually by contaminated food or water
(Slide 14)

40
Q

How are micro and macrogametes produced in the lifecycle of cryptosporidium parvum after it is ingested / inhaled by a host?

A

Firstly it excysts, then sporozoites are released and parasitize the epithelial cells of the GI tract. Here, they undergo asexual production and then sexual reproduction which produces microgamonts (male) and macrogamonts (female)
(Slide 15)

41
Q

How do micro and macrogamonts produce thin and thick walled oocysts in the life cycle of cryptosporidium parvum?

A

The macrogametes (female) are fertilised by microgametes which rupture from the microgamont (male), resulting in oocysts developing and sporulating within the infected host, there are 2 types of oocysts, thick and thin walled, with thin walled oocysts being involved in the autoinfection cycle while thick walled oocysts are excreted and contribute to infecting a new host
(Slide 15)

42
Q

What is toxoplasma gondii?

A

Apicomplexan (of the phylum Apicomplexa) protist that is a parasite in warm-blooded animals
(Slide 20)

43
Q

How does oocyst production in toxoplasma gondii compare?

A

Toxoplasma gondii can only produce oocysts in it’s definitive hosts (cats) whereas cryptosporidium parvum can produce oocysts in it’s definitive or intermediate hosts
(Slide 20)

44
Q

How is toxoplasma gondii transmitted?

A

Mainly via c ats but also through undercooked meat
(Slide 20)

45
Q

Can toxoplasmosis be asymptomatic?

A

Yes, and it usually is
(Slide 20)

46
Q

What parts of the body can toxoplasmosis damage in immune-comprised individuals?

A

The eyes, brain and other organs
(Slide 20)

47
Q

What effect can toxoplasmosis cause?

A

Birth defects (teratogenic)
(Slide 20)

48
Q

What can be used to treat toxoplasma gondii?

A

Sulphadiazine
Pyrimethamine
Spiromycin
(Slide 20)

49
Q

What is a tachyzoite (toxoplasma gondii)?

A

Rapidly dividing forms of the parasite which are responsible for acute infection. They actively replicate within host cells and are responsible for the rapid spread of the infection
(Slide 16)

50
Q

What is a bradyzoite (toxoplasma gondii)?

A

A slow-growing dormant form of the parasite, with some tachyzoites differentiating into bradyzoites after the acute infection subsides.
(Slide 16)

51
Q

What do bradyzoites allow (toxoplasma gondii)?

A

They allow the parasite to persist in the host for long periods of time without causing significant symptoms
(Slide 16)

52
Q

What can bradyzoites do under the right conditions (such as an individual becoming immunocompromised)?

A

Reactivate to tachyzoites
(Slide 16)

53
Q

What are the only known definitive hosts of toxoplasma gondii?

A

Cats
(Slide 18)

54
Q

What are 3 examples of potential intermediate hosts which toxoplasma gondii can infect?

A

Answers include:
Sheep
Pigs
Birds
Rodents
Humans
(Slide 18)

55
Q

What occurs in the lifecycle of toxoplasma gondii?

A

Oocysts are excreted from cat via faeces, they are shed for 1-3 weeks and take 1-5 days to sporulate in the environment. A intermediate host then becomes infected via ingesting infected soil, water or plant material. The oocysts then transform into tachyzoites before developing into tissue cyst bradyzoites. Cats then become infected after ingesting intermediate hosts harbouring tissue cysts or by directly ingesting sporulated oocysts. Animals bred for wild game can also being infected by eating something which has tissue cysts
(Slide 18)

56
Q

What are 4 ways can humans become infected from the toxoplasma gondii life cycle?

A

Eating undercooked meat of animals harbouring tissue cysts

Consuming food or water contaminated with cat faeces or by contaminated environmental samples

Blood transfusion or organ transplant

Transplacentally from mother to fetus
(Slide 18)

BM211: Introduction to Microbiology (21 decks)

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