RA3: Intro to Clinical Parasitology

Question 0

Endoparasite

Answer 0

Live within body of host, mostly protozoa and helminths

Question 1

Ectoparasite

Answer 1

Live on the surface of their host, usually arthropods (ex. ticks and mites)

Question 2

Obligate vs. facultative

Answer 2

Obligate must spend at least part of their life cycle in association with host, while facultative are capable of leading both free or parasitic existence

Question 3

Vector

Answer 3

Insect that transmits infectious agent from one host to the next

Question 4

Protozoa

Answer 4

Unicellular eukaryotic microbe

Question 5

Helminths

Answer 5

Worms that can vary in length and are covered in cuticle

Question 6

Nematode

Answer 6

Roundworm

Question 7

Cestode

Answer 7

Tapeworm

Question 8

Trematode

Answer 8

Fluke (complex flatworms)

Question 9

Definitive host

Answer 9

Host in which the parasite reaches sexual maturity

Question 10

Intermediate host

Answer 10

Host that harbors larval or asexual stages of parasite

Question 11

Reservoir host

Answer 11

Definitive host (animal) that serves to maintain parasite’s life cycle in environment

Question 12

Cysts

Answer 12

Environmentally resistant, facilitate transmission to hosts (normally protozoa)

Question 13

Trophozoite

Answer 13

Metabolically active, motile, feeding stage of parasitic protist

Question 14

4 classes of protozoa

Answer 14

1. Amoeba (pseuodopodia)
2. Flagellates (flagella)
3. Sporozia (gliding)
4. Ciliates (cilia)

Question 15

Schizogony

Answer 15

Asexual reproduction process of sporozoans and amoebas

Question 16

Sporogony

Answer 16

Sexual form of reproduction that entails multiple nuclear divisions followed by cytokinesis after zygote formation

Question 17

3 factors in transmission of parasitic diseases

Answer 17

1. Source of infection
2. Mode of transmission
3. Presence of susceptible host

Question 18

Ingestion

Answer 18

Oral transmission due to consumption of food/water contaminated with parasite eggs or cyst; fecal contamination implicated in transmission of parasitic diseases

Question 19

Penetration/inoculation

Answer 19

Larval forms of some helminths found in soil or water can penetrate skin of host

Question 20

Direct transmission

Answer 20

Trichomonas vaginalis, causative agent of common STD, is transmitted through sexual contact

Question 21

Congenital transmission

Answer 21

Transmission from mother to infant (toxoplasmosis, malaria)

Question 22

Transfusion and transplantation

Answer 22

Potentially any blood or tissue dwelling parasite, seen in malaria and trypanosomes

Question 23

Mechanical damage by parasites

Answer 23

Caused by presence or movement of parasite (lots of worms)

Question 24

Damage caused by parasite products

Answer 24

Helminths and intestinal protozoa produce products aiding in establishment and persistence of infections

Question 25

Immunopathology

Answer 25

Response of host to parasitic infection; ex. granulomas can disrupt blood flow

Question 26

Immune responses to protozoal infection

Answer 26

1. Neutralizing antibody 2. Antibody + complement 3. Antibody/complement opsinization 4. Activated macrophages 5. CD8+ cytotoxic T cells

Question 27

What problems do helminthic infections pose?

Answer 27

- -Too big for phagocytosis - -Often covered with protective cuticle or sheath to protect against complement-mediated lysis - -Eosinophilia is hallmark of these

Question 28

Size in evasion of immune defense

Answer 28

Helminths unlikely to be phagocytosed or destroyed by macrophages or neutrophils due to large size

Question 29

Anatomical location in evasion of immune defense

Answer 29

Residing in lumen makes difficult to reach them

Question 30

Intercellular sequestration in evasion of immune defense

Answer 30

Residing for a period of time sequesters from destruction by humoral defenses

Question 31

Formation of cyst in evasion of immune defense

Answer 31

Provide impenetrable barriers to immune system

Question 32

Avoidance of phagolysosomal destruction in evasion of immune defense

Answer 32

Some parasites can survive and replicate in inhospitable environment of lysosomes

Question 33

Antigenic variation in evasion of immune defense

Answer 33

Different forms of malaria have different antigens, African trypanosomes have new waves every so often that has different antigens

Question 34

Antigenic masking in evasion of immune defense

Answer 34

Larval and adult forms of helminths will cost in proteins or lipids to mask antigens from immune system

Question 35

Immunosuppression in evasion of immune defense

Answer 35

Infected individual can become susceptible to secondary infections

Question 36

Anti-protozoal drugs

Answer 36

Target rapidly proliferating metabolically active cells

Question 37

Anti-helminths

Answer 37

Targeted at non-proliferating adult helminths