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My Packs: (UWO) (MICROIMM 2500) > (Section D: Other Infectious Agents) Lecture 26 > Flashcards

(Section D: Other Infectious Agents) Lecture 26 Flashcards

1
Q

Parasite

A

“Parasitos”
* Para = On
* Beside = Food

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2
Q

What organisms can be parasites?

A
  1. Animals
  2. Plants
  3. Fungi
  4. Bacteria
  5. Viruses
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3
Q

How are parasites organized?

A
  • Protozoa
  • Metazoa
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4
Q

What are examples of metazoa?

A
  • Helminths
  • Arthropods
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5
Q

What type of organisms are protozoa?

A

Single cell eukaryotes

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6
Q

What type of organisms are metazoa?

A

Macroscopic, multicellular, eukaryotes

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7
Q

Advantages of Parasitism

(8)

A
  • No need for searching once host is found
  • Food permanently available
  • Limited requirement for complicated food capturing mechanisms
  • Reduced need for food processing
  • Protection from environmental extremes
  • Protection from predators and diseases
  • Reduced need for dispersal
  • Can devote energy to reproductive output
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8
Q

Disadvantages of parasitism

(6)

A
  • Extreme host specificity increases vulnerability to extinction
  • Must locate at optimal site on/in host to ensure food/survival
  • Must adapt to host’s internal physiological environment
  • Must overcome host’s immune defenses
  • Spread limited by host’s geographic range
  • Transmission extremely risky
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9
Q

Different forms of parasites

A
  1. Facultative
  2. Obligate
  3. Endoparasites
  4. Ectoparasites
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10
Q

Facultative parasites

A

Free living or Live inside host

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11
Q

Obligate parasites

A

Must live in host

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12
Q

Endoparasites

A

Live inside host

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13
Q

Ectoparasites

A

Live outside host

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14
Q

Parasitic protozoa
* Number described
* Number currently living
* Number adapted as parasites
* Number isolated from humans

A
  1. Over 200,000 species
  2. 35,000 species
  3. 10,000 species
  4. ~70 different species
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15
Q

Can protozoa infect invertebrates?

A

Yes, parasitic protozoans infect a wide spectrum of vertebrate and invertebrate life

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16
Q

All protozoans are…

A

Eukaryotic, single-celled organisms

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17
Q

What is the conventional classification of parasites?

A

By motility
1. Flagellates
2. Amoeboids
3. Apicomplexans
4. Ciliates

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18
Q

Flagelletes

A

Mastigophora
* Use flagella to move

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19
Q

Amoeboids

A

Sarcodina
* Protoplasm pushes them around

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20
Q

Apicomplexans

A

Sporozoa
* Glide to move

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21
Q

Ciliates

A

Ciliophora
* Cilia help facilitate movement

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22
Q

Do parasites group only into a single category of motility?

A

No, they can have multiple forms of motility (overlapping between categories)

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23
Q

What is used in modern classification of parasites?

A

Metabolism and Genotype

24
Q

What is are mechanisms of entry for parasites?

A
  1. Oral (Giardia duodenalis)
  2. Sexual (Trichomonas vaginalis)
  3. Inhalation (Toxoplasma gondii)
  4. Direct Contact (Trypanosoma cruzi)
  5. Arthropod vectors (Plasmodium falciparum)
25
Q

What are the different types of parasite hosts?

A
  1. Definitive (Final)
  2. Intermediate
  3. Reservoir
26
Q

Definitive host

A
  • Sexual maturity
  • Sexual reproduction
  • Most crucial for parasite’s lifecycle
27
Q

Intermediate host

A
  • Asexual reproduction
  • Development stage, not at sexual maturity
28
Q

Reservoir host

A

Serves to harbour the parasite and be a source of infection

29
Q

What type of reproduction can parasites undergo?

A
  1. Asexual
  2. Sexual
  3. Both
30
Q

Oral transmission

A

Ingest

31
Q

Sexual transmission

A

Keeps the parasite in human conditions, prevents exposure to outside environment

32
Q

Inhalation transmission

A

Aerosolized particles that are breathed in

33
Q

Direct contact

A

Parasite enters via direct contact (rubbing a wound etc.)

34
Q

Aseuxal reproduction

A

Kind of like binary fission and mitosis

35
Q

Sexual reproduction

A

Kind of like meiosis where sperm and eggs come together

36
Q

Do some organisms have both asexual and sexual reproduction?

A

Yes

37
Q

State the term for:

  1. One host
  2. 2 different hosts
  3. 3 different hosts
A
  1. Monoxenous
  2. Diheteroxenous
  3. Triheteroxenous
38
Q

What are methods for parasite survival and pathogenesis?

A
  • Antigenic variation
  • Molecular mimicry
  • Immune modulation
  • Intracellular habitation
  • Encapsulation
  • Protease secretion
  • Thermal tolerance
  • Toxin production
  • Nutrient deprivation
  • Others…
39
Q

Pathogenesis Methods:

Expressing different surface proteins, changing frequently

A

Antigenic variation
* Helps hides from immune system

40
Q

Pathogenesis Methods:

Proteins and molecules that look like the host

A

Molecular mimicry
* Tricks host into thinking it isn’t foreign

41
Q

Pathogenesis Methods:

Releasing thing that suppress/modulate immune system

A

Immun modulation

42
Q

Pathogenesis Methods:

Get inside host cells to hide

A

Intracellular habitation

43
Q

Pathogenesis Methods:

Forming capsule or cyst to protect from external conditions

A

Encapsulation

44
Q

Pathogenesis Methods:

Destroy proteins inside the host

A

Protease secretion

45
Q

Pathogenesis Methods:

Adapt to temperatures

A

Thermal tolerance

46
Q

True or False:

Toxin production is intentional

A

Not all the time; sometimes it is a by product

47
Q

Giardia duodenalis
* What is it
* Living place
* Nucleus
* Type of parasite
* Life cycle
* Transmission

A
  1. Most prevalent protozoan human intestinal pathogen
  2. Upper small intestine of vertebrate host
  3. Binucleated
  4. Obligate parasite, aerotolerant anaerobe (no mitochondria)
  5. Monoxenous, two stages (trophozoite and cyst)
  6. Fecal-oral route
48
Q

Giardia duodenalis:

Cyst

A
  • Environmentally stable
  • Facilitates transmission
  • Tetranucleate
  • Oblong shape (5 μm by 7-10 μm in size)
  • Metabolic rate is low (10-20% of a trophozoite)
49
Q

Giardia duodenalis:

Trophozoite

A
  • Adapted for survival within small intestine
  • 8 μm by 12-15 μm in size
  • Binucleate (both transcriptionally active, diploid)
  • Four pairs of flagella
  • Adhesive disc
  • Mitosomes (no mitochondria)
50
Q

Lifecycle

A
  1. Ingestion (cyst)
  2. Excystation (due to low pH in stomach)
  3. Forms 2 trophozoites (in small intestine)
  4. Adhere/Residence (in villi of small intestine)
  5. Reproduces asexually
  6. Encystation (some repackage into cysts)
51
Q

What can the tropozoites adhering to the small intestinal mucosa result in?

A

Atrophy and flattening of the villi

52
Q

What are major reservoir hosts for G. duodenalis?

A

Beavers
* Hence the nickname “beaver fever”

53
Q

Giardia duodenalis secretions

A
  • Proteases
54
Q

What secreted and expressed proteins are present in G. duodenalis?

A
  • Excretory secretory products (ESPs)
  • Variant-specific proteins (VSPs)
55
Q

Diagnosis for Giardia duodenalis

A
  1. Gold standard: Microscopy
  2. Antigen capture ELISA
  3. Direct fluorescent antibody test (DFA)
  4. Nucleic Acid Amplification Tests (NAATs)
56
Q

Treatment for Giardia duodenalis

A

Nitroimidazoles (e.g. metronidazole)
* Inactivated when taken
* Ferredoxin responsible for reducing pyruvate to ATP activates the drug by reducing it
* Can’t happen in human cells as the reduction power isn’t strong enough

My Packs: (UWO) (MICROIMM 2500) (26 decks)

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