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Disease Ecology > Lecture 4 Parasite diversity 4 Protozoa > Flashcards

Lecture 4 Parasite diversity 4 Protozoa Flashcards

1
Q

What is a protozoan?

A

• animal-like eukaryote:
- no cell wall
- at least 1 motile stage in life cycle
-most ingest their food
• not a monophyletic (1 common ancestor) clade but share a basic body plan completely contained within 1 plasma membrane,
i.e. single-celled

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2
Q

Where do we find protozoa?

A

Everywhere!
• all require moisture (prone to drying out)
• many free-living but also numerous symbionts
- mutualistic, commensals, parasites

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3
Q

How do we classify protozoa?

A

• constantly under revision due to new molecular data

–>will focus on clades rather than taxonomic levels

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4
Q

Describe the protozoan clade Diplomonads.

A

no mitochondria,
-> symbionts (dependent on host)
2 nuclei, flagella

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5
Q

Name the Genus found in Diplomonads clade.

A

Giardia

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6
Q

Describe Genus Giardia

A

2 forms ( trophozoite & cyst)
• direct transmission (via
ingestion)

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7
Q

Describe trophozoite and cysts of Giardia

A

cyst-> trophozoite undergo asexual replication-> cycsts and trophozoites expelled in feces -> only cycsts can survive outside of host-> cyst can survive for weeks to months in cold water

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8
Q

Describe structure of Giardia found in Diplomonads?

A
  • host cell adhesion (ventral disc)

- -> groove suction prevent being cleaved by digestion system

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9
Q

Describe life cycle of Giardia

A

Bever Fever nickname:

  • wildlife imp reservoir
  • > hosts for many pathogens
  • direct or waterbourne
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10
Q

Describe characteristics of clade Alveolata in Protozoa.

A
  • membrane-bound sacs (alveoli) under plasma membrane
  • 3 phyla members:
  • parasitic group Apicomplexa, cilia group Ciliophora with some parasites
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11
Q

Describe characteristics of Phylum Apicomplexa

found in clade Alveolata.

A 
1 end (apical complex) contains organelles specialized for penetrating host cells & tissues
• intricate life cycles (sexual & asexual stages) that often require 2 or more hosts 
• members: endoparasites
• divided into 2 classes based on presence
of conoids (found in apical complex)
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12
Q

What is the structure inside the apical end which release enzymes for penetrating the host?

A

Rhoptries

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13
Q

Describe Toxoplasma gondii an Apicomplexans of note.

A

cat parasite
- intracellular – various tissues (muscle, intestine, other)
• asexual & sexual
reproduction occur in different hosts
- sexual reproduction only in cats during intestinal phase
—->oocysts released in feces

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14
Q

What do 4 Toxiplasma gondii sporozites do?

A

they open oocyte in muscle tissue

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15
Q

Why is Toxoplama gondii called a cat parasite and ways of human exposure?

A

2 ways:

  • cleaning litter box
  • uncooked pork and gut
  • placental infection, baby brain affected

-intermediate host can be a rat which cats eat

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16
Q

What happens if oocysts are eaten?

A

sporocysts enter host cells (extra- intestinal)
—> rapidly dividing tachyzoites accumulate in cells
• zoitcysts with bradyzoites form (baby brain)
–>persist for years
• zoitocysts big problem if in fetus
• in
~ 25% of world population • immunocompromised,
schizophrenia(?)

17
Q

Links that schizophrenia can occur due to toxoplasma gondii. How?

A

parasite manipulate host to increase transmission b/c in brain
ex. rodents are attracted to cat, cat urine

18
Q

Describe Neospora caninum in Phylum Apicomplexa.

A

-dogs as definitive hosts
• transplacental infection of other species
 leading cause of abortion in dairy cattle
-doesn’t use humans as accidental hosts but livestock
-tachyzoites transmitted through placenta

19
Q

Describe:Genus Plasmodium in Phylum Apicomplexa.

A 
-intracellular (vertebrate
  blood & other tissues)
 • asexual & sexual
reproduction occur in different hosts
• cause of malaria disease
 known since antiquity
20
Q

What 3 similarites does plasmodium have with tachyzoite of toxoplasma gondii?

A

apical polar ring, micronemes and rhoptries. no conoid in plasmodium

21
Q

Describe history of malaria from Plasmodium

A

similar to yellow fever, no control if no information
-1847, notice pigment granules in blood and speen
-1891 staining techniques no
Ronald Ross:
-correctly found mosquito as vector

22
Q

What is the ring stage in Plasmodium?

A

imp for species i.d. -some are worse than others
Adhering:
trophozoite->schizont-> merozoites->
Circulating:
merozoites-> gametocytes-> ring-> trophozoite

-merozoite penetrate RBC

23
Q

So you’ve got a persistent parasite…What sort of pathology results?

A

continually changes _surface proteins

  • –>wears out immune system
  • fever & chill periodicity w/ diff types of bacteria
  • cerebral malaria (RBC stick together to form clumps stuck fine capillaries, clumping in vascular region of brain
24
Q

How can we control malaria?

A

i) control transmission via vector
• old-fashioned & new methods
–> bed nets

–>GM males break vector life cycle (sterile males)

ii) control transmission via parasites-give anti-malarial drugs
iii) control transmission via human susceptibility

25
Q

Describe iii) control transmission via human susceptibility for malaria

A
  • merozoite surface proteins (block RBC invasion)
  • sporozoites: start some immune response
  • mosquito stages: block parasite development
  • sequencing Plasmodium genome may help identify potential vaccine targets
26
Q

Why care about malaria?

A

affects 300 million people (2 million deaths/yr)
productivity declines
-changes in
temperature & precipitation 40% transmission• examine historic distribution re-emergence likely

27
Q

What are related blood parasites to plasmodium?

A 
Haemoproteus spp.:
• primarily birds & other reptiles
-->_non-mosquito_ vectors
Leucocytozoon spp.: 
• bird parasites
--> _blackfly_ vector
28
Q

Describe Icthyophthirius multifiliis found in Phylum Ciliophora

A 
a.k.a. “_Ick_”
• disease in freshwater fish • adult trophonts reproduce
asexually (_fission)
• daughter trophonts
(tomonts) emerge & encyst
--->become tomites that divide
-asexual -> high #'s
-direct transmission-> hard to control
- infective theronts break from tomites
--->seek fish host (cues), like movement, chemical
• highly transmissible
-"whitespot" disease
29
Q

What are trophonts in ichthyophthirius multifiliis?

A

-adult trophonts reproduce asexually via fission in fish

30
Q

What are tomonts in ichthyophthirius multifiliis?

A

-they are daughter trophonts that emerge and encyst

31
Q

What are tomites in ichthyophthirius multifiliis?

A

tomites that are encysted become tomites which divide

32
Q

What are theronts in ichthyophthirius multifiliis?

A

are infected and break free from tomites

– they seek fish host, “white spot disease”

Disease Ecology (7 decks)

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