Clinical Parasitology- RA3 Flashcards Preview

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Flashcards in Clinical Parasitology- RA3 Deck (34):
1

Parasitism

One organism benefits at the expense of another

2

Symbiosis/ Mutualism

Both partners benefit from each other

3

Commensalism

One partner benefits, the other is unaffected

4

Ectoparasite

Lives on surface of the host (e.g. arthropods)

5

Endoparasite

Lives within the host (e.g. protozoa & helminths)

6

Obligate parasite

Must spend at least part of the lifecycle associated with host

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Faculative parasite

Capable of living a free & parasitic existence

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Vector

Insect that transmits infectious agent

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Protozoa

Uunicellular eukaryotic microbe

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Helminth

Worm

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Namatode

Roundworm

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Cestode

Tapeworm

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Trematode

Fluke (flatworm)

14

Describe the prevalence of parasitic diseases worldwide & especially in developing/under-developed countries.

"Parasitic infections currently account for greater morbidity & mortality than any other class of infectious agent in developing or under-developed countries."

15

List the characteristics of protozoa.

- Single celled eukaryotes
- Nucleated
- Contain organelles
- Many encyst themselves

16

List the characteristics of helminths.

- Multicellular
- Elongated appearance
- Covered by a thick membranous coating called a cuticle

17

How are protozoa classified?

Based on locomotion

18

What are the four classes of protozoa?

Ameba
Flagellates
Sporozoa
Ciliates

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Ameba

Pseudopodia

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Flagellates

Flagella

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Sporozoa

Gliding

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Ciliates

Cilia

23

What is special about the reproductive mechanism of the sporozoa?

Reproduction by schizogony

24

What is Schizogony?

Multiple intracellular nuclear divisions prior to cytoplasmic divison

25

How are Helminths classified?

Roundworm vs. Flatworm

26

What group belongs to the roundworms?

Namatodes

27

What groups belong to the flatworms?

Cestodes & Trematodes

28

What is the difference between Cestodes & Trematodes?

Cestodes= Tapeworm that is segmented & lacks a digestive tract

Trematode= non-segmented "Fluke"

29

List the modes of parasitic transmission.

- Ingestion
- Direct penetration of skin
- Inoculation by vectors
- Congenital transmission
- Transmission by transfusion or transplantation

30

What are the mechanisms of parasitic disease?

- Mechanical damage
- Damage caused by parasitic products
- Damage caused by the immune response to the parasite

31

How does the immune response to protozoa differ from the response to helminths?

Protozoa= typical response similar to what would be seen against virus or bacteria

Helminths= IgE & eosinophil dominated

32

How do parasites evade the immune system?

- Size = often too large to be phagocytosed
- Anatomical Location= residence in the gut makes it difficult for immune system to reach them
- Intracellular sequestration
- Formation of a cyst
- Avoidance of phago-lysosomal destruction
- Antigenic variation
- Antigenic masking
- Immunosuppression

33

What is the major challenge to chemotherapeutic & immunological interventions to parasitic disease?

- Parasitic organisms are eukaryotic cells & are very similar to human cells
- Thus, treatment often results in toxicity to the host
- Differential toxicity is achieved by using drugs that are metabolically altered only by the parasite

34

What are the two major drug groups used in treating parasitic infections?

- Anti-protozoals= target rapidly proliferating, metabolically active cells
- Anti-helminths= Affect the neuromuscular system, carbohydrate metabolism, or egg production of adult worms

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