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PARA434 > Lecture 4: Protozoan Parasites > Flashcards

Lecture 4: Protozoan Parasites Flashcards

1
Q

what is a protozoa?

A

usually defined as protists that are more animal like than plant like

most of them are motile, although they don’t photosynthesize.

they can live in different areas of the body (different hosts).

  • the gut, liver, spleen, heart, eyes, etc
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2
Q

protozoa are divided into 4 main groups, what are they?

A
  1. amoeba
  2. flagellates
  3. cilliates
  4. sporozoa
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3
Q

from the point of view of functional and physiological complexity, a protozoan is more like an animal or single cell?

A

more like an animal than a single cell

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4
Q

what is niche selection

A

selected to live in a specific essential niche defined by anatomical, physiological and biochemical features of the site.

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5
Q

what are two types of stages in the complex life cycle of parasites?

A
  • asexual and sexual reproduction
  • resistant cyst stage (not all) (protection stage)
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6
Q

describe motility in amoebas

A
  1. Extension (the formation of long actin filaments at the leading edge extends the lamellipodium)
  2. Adhesion
  3. Translocation (rearrangement of the actin cytoskeleton in other regions of the cell causes the cell to be pulled toward the leading edge.
  4. De-adhesion
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7
Q

flagellum vs cilia movement?

A

cilia: back and forth beating
you will see multiple around exterior

flagellum: propeller-like motion
only a few

there will always be a basal body (anchor).

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8
Q

how do sporozoa move?

A
  • NO FLAGELLA, CILLIA OR PSEUDOPOD
    • They have an actin-myosin that attach to the surface that move unidirectionally.
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9
Q

how do protozoa reproduce asexually (2)

A
  • binary fission and multiple fission

they are variations on mitotic division

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10
Q

how do protozoa reproduce sexually?

A

by gamete fusion

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11
Q

Apicomplexan life cycle

A
  • You have one part of it that is the sexual stage
  • Haploid stage and diploid stage.
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12
Q

define sporogony

A

multiple fission of a zygote

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13
Q

define sporozoite

A

daughter cell resulting from sporogony

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14
Q

define schizogony

A

fission of sporozoites where multiple mitoses take place followed by simultaneous cytokineses, resulting in many daughter cells all at once.

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15
Q

define Gametogony

A

production of gametes

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16
Q

define zygote

A

fusion of gametes (meiosis may occur after fusion).

17
Q

what is the apical complex?

A
  • For the invasion of the parasite into the host.
    • Has a few different structures belonging to it.
    • At the apical end of the cell
    • Contains rhoptries , micronemes, dense granules, polar rings and a conoid
    • Reason why the group is called apicomplexa parasites is because they form apical complex: which helps the organism invade the host.
      Apical complex feeds the host cell with many substances to ruin the integrity of cell membrane.
18
Q

Why do Apicoplast have 4 membranes?

A
  • One ancestral cell takes up a bacteria and if this new organism now takes up another organism
    • So this is a product of primary and secondary endosymbiosis.
19
Q

oocysts vs sporozoites?

A

oocysts: released into the environment with diarrhea (infective stage)

sporozoites: what causes pathology/diarrhea

20
Q

how are you infected with oocytes?

A
  • Sporulated oocysts will infect you. You can take them up when drinking contaminated water. Sometimes can be food sources.
    Zoonotic transmission will occur with cryptosporidium because they ae not host specific and can live in animals and humans.
21
Q

The emergence of sporozoite

A
  • Sporozoite will enter small intestine and enter a cell
    • Develop into tropozoite where it has an asexual life cycle (Type I meront)
    • Several merozoites will be leaving the asexual cycle.
      ○ Some merozoite will differentiate into type II. Merozoite will break up into gamont.
      ○ Differentiate into micro and macrogamont (male and female) for sexual reproduction.
      You can reinfect yourself again and again.
22
Q

How many sporozoites within an oocyte?

A
  • Oocyte wall is unique with a suture at the end
    -The suture dissolves during excystation, opening the wall to 4 sporozoites.
23
Q

How many oocysts to initiate infection?

A
  • Ingest 30 oocytes within drinking water
    They are highly infective.
24
Q

How do you get infected?

A
  • Fecal oral route
    • If animals are in the environment that release this into the environment with their feces, you can get infected as well.
      Cryptosporidium is not host specific.
25
Q

Who is at risk to getting infected with cryptosporidium

A
  • Workers
    ○ Veterinarians, farmers, medical personnel, day-care centers
    • Social factors
      ○ Family, children, pet owners, travelers, drinking non-filtered water.
      Immuno-deficient people
26
Q

What are the symptoms of cryptosporidium infection

A
  • Some individuals can be asymptomatic (releasing the parasite into the environment unknowingly)
    • Symptoms last 1-2 weeks.
    • Symptoms include:
      Stomach cramps, pain, watery diarrhea, dehydration, weight loss, vomiting, fever.
27
Q

What is the cryptosporidium pathology?

A

-cryptosporidium resides at the apical surface of intestinal epithelial cells and does not invade deeper layers of the human gastrointestinal mucosa

-metabolites are secreted by cryptosporidium

  • inflammation and disruption of salt-water balance of the intestinal epithelium as the parasite replicates
  • mucosal inflammation with the presence of macrophages and neutrophils at the site of infection
  • classical immune response to infectious agents
28
Q

How to diagnose / treat someone with cryptosporidium infection?

A
  • Microscopy test to diagnose
    • No treatment. Immuno-competent individuals will recover.
    • Difficult to manage for AIDS patients
      Because there is no treatment.
29
Q

How to prevent or control crypto?

A
  • You usually get infected by taking in water
    The crypto oocyst is resistant to chemical disinfectants but is susceptible to drying (no longer in moist area) and UV rays.
30
Q

Prevention and control of crypto

A
  • Water purification and filtration.
    Even if you think water is clean, you can filter to ensure no oocytes.

PARA434 (6 decks)

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