Introduction Parasitology

Question 1

Define carrier

Answer 1

Harbors a particular pathogen without manifesting any signs and symptoms

Example: Entamoeba histolytica in food handlers

Question 2

What is the meaning of ‘exposure’ in infectious disease terms?

Answer 2

Process of inoculating an infective agent

Question 3

Define ‘infection’.

Answer 3

Establishment of the infective agent in the host

Question 4

What is the ‘incubation period’?

Answer 4

Period between infection and evidence of symptoms

Question 5

What is the ‘pre-patent period’?

Answer 5

Also known as biological incubation period, period between infection or acquisition of the parasite and evidence or demonstration of infection

Question 6

What is ‘autoinfection’?

Answer 6

Results when an individual becomes his own direct source of infection

Question 7

Fill in the blank: The parasite _______ is associated with autoinfection.

Answer 7

Capillaria philippinensis

Enterobius vermicularis

Hymenolepis nana

Strongyloides stercoralis

Question 8

What is a superinfection?

Answer 8

An infection where an already infected individual is further infected with the same species leading to a massive infection

This can occur when the immune system is compromised or when the initial infection is not adequately treated.

Question 9

Define streamlining in the context of parasites.

Answer 9

Inability of the parasite to synthesize certain cellular components and the need to obtain these from a host

This leads to changes in the metabolic pathways of the parasite.

Question 10

What is an obligatory parasite?

Answer 10

A parasite that cannot survive outside of a host.

Question 11

What is a facultative parasite?

Answer 11

A parasite that is capable of existing independently of a host.

Question 12

Define an endoparasite.

Answer 12

A parasite that is established inside of a host.

Question 13

What is an ectoparasite?

Answer 13

A parasite that is established in or on the exterior surface of a host.

Question 14

What is an erratic parasite?

Answer 14

A parasite found in an organ which is not its usual habitat.

Question 15

Define an accidental or incidental parasite.

Answer 15

A parasite that establishes itself in a host where it does not ordinarily live.

Question 16

What is a permanent parasite?

Answer 16

A parasite that remains on or in the body of the host for its entire life.

Question 17

What is a temporary parasite?

Answer 17

A parasite that lives on the host for a short period of time.

Question 18

Define a spurious parasite.

Answer 18

A free-living organism that passes through the digestive tract without infecting the host.

Question 19

What is an accidental or incidental host?

Answer 19

A host other than the normal one that is harbouring a parasite.

Question 20

Define a definitive or final host.

Answer 20

The host in which the adult sexual phase of parasite development occurs.

Question 21

What is an intermediate host?

Answer 21

A host in which the larval asexual phase of parasite development occurs.

Question 22

What is a paratenic host?

Answer 22

A host where the parasite does not develop further but is alive and able to infect another susceptible host.

Question 23

Define a reservoir host.

Answer 23

A host harbouring parasites that are parasitic for humans and from which humans may become infected.

Question 24

What is a transport host?

Answer 24

A host responsible for transferring a parasite from one location to another.

Question 25

What is a carrier in parasitology?

Answer 25

A parasite-harbouring host that is not exhibiting any clinical symptoms but can infect others.

Question 26

What is a biologic vector?

Answer 26

A vector that transmits the parasite only after the latter has completed its development within the host.

Question 27

Define a mechanical or phoretic vector.

Answer 27

A vector that only transports the parasite.

Question 29

What is symbiosis?

Answer 29

Living together; the association of two living organisms, each of a different species.

Question 30

Define commensalism.

Answer 30

Association of two different species of organisms that is beneficial to one and neutral to the other.

Question 31

What is mutualism?

Answer 31

Association of two different species of organisms that is beneficial to both.

Question 32

Define parasitism.

Answer 32

Association of two different species of organisms that is beneficial to one at the other's expense.

Question 33

What does commensal refer to?

Answer 33

Relating to commensalism; the association between two different organisms in which one benefits and has a neutral effect on the other.

Question 34

What is a pathogenic parasite?

Answer 34

A parasite that has demonstrated the ability to cause disease.

Question 35

How do parasites interfere with the vital processes of the host?

Answer 35

Through parasitic enzymes.

Question 36

What do secretory and excretory products of parasites allow them to do?

Answer 36

Metabolize nutrients obtained from the host and store these for energy production.

Question 37

What do Entamoeba histolytica trophozoites secrete?

Answer 37

Cysteine proteinases, which digest cellular materials and degrade epithelial basement membrane facilitating tissue invasion.

Question 38

What happens to the host's red blood cells due to Plasmodium?

Answer 38

They rupture, resulting in the release of merozoites.

Question 39

What is the effect of Schistosoma japonicum on the liver?

Answer 39

Cumulative deposition of eggs leads to immune response mechanism, granuloma formation, fibrosis, portal hypertension, and massive hemorrhage in the venules.

Question 40

How do hookworms affect the intestinal mucosa?

Answer 40

They use cutting plates to attach and destroy the villi.

Question 41

What can massive intestinal bleeding from heavy hookworm lead to?

Answer 41

Chronic blood loss and iron deficiency anemia.

Question 42

What does Diphyllobothrium latum compete with its host for?

Answer 42

The available supply of Vitamin B12, leading to megaloblastic anemia.

Question 43

What genetic factor provides protection in falciparum malaria?

Answer 43

Sickle-cell trait.

Question 44

What blood factor is associated with susceptibility to Plasmodium vivax?

Answer 44

Duffy blood factor.

Question 45

What type of diet is unsuitable for intestinal protozoans?

Answer 45

Rich-protein diet.

Question 46

What type of diet can lead to amebiasis?

Answer 46

Low-protein diet.

Question 47

What type of diet is favorable for tapeworms?

Answer 47

High-carbohydrate diet.

Question 48

Is absolute immunity to reinfection common in protozoan infections?

Answer 48

False.