Lecture 1: introduction

Question 1

What is a parasite?

Answer 1

Eukaryotic organisms that have to live in or on other organisms (hosts) to complete its natural life cycle

Question 2

What is commensalism?

Answer 2

A relationship between microorganism and host where the benefit is uni-directional. (micro)organism benefits, host is neither harmed nor helped

Question 3

What is mutualism?

Answer 3

A relationship between a microorganism and a host where te benefit is bidirectional. Both the (micro)organism and the host benefit from the relationship

Question 4

What is symbiosis?

Answer 4

“organisms living together”. A close association between two organisms; microorganism and host

Question 5

What is parasitism?

Answer 5

A relationship between a microorganism and a host where the benefit is uni-directional. The microorganism benefits and the host is harmed

Question 6

What is the difference between endo- and ectoparasites?

Answer 6

Endoparasite vs ectoparasite: IN vs. ON the host. An endoparasite lives IN the host and an ectoparasite lives ON the host. When a patient has endoparasites in them, it’s called an infection. When a patient has ectoparasites on them, it’s called an infestation.

Question 7

What is the difference between a facultative and an obligate parasite?

Answer 7

Facultative: the parasite may exist in a free living state
Obligate: the parasite cannot survive without its host

Question 8

What is a definitive host?

Answer 8

Definitive host: host in which sexual replication takes place

Question 9

What is an intermediate host?

Answer 9

Intermediate host: only asexual replication takes place in the host

Question 10

What is an accidental host?

Answer 10

Accidental host: parasite is seldom found in this host (infected by accident)

Question 11

In which two groups can endoparasites be split?

Answer 11

Protozoa (unicellular) and metazoa (multicellular)

Question 12

How can you classify protozoa?

Answer 12

You can divide protozoa into 4 groups based on their organelles of locomotion:
-Rhizopods
-Cilliates
-Flagelates
-Sporozoans
OR
You can divide protozoa into 2 groups based on their reproduction:
-Binary fission
-Schizogony

Question 13

What is a direct life cycle?

Answer 13

Direct lifecycle: parasite needs one host to complete its life cycle. E.g. Enterobius. Eggs are ingested via the mouth and secreted via the intestinal tract.

Question 14

What is an indirect lifecycle?

Answer 14

Indirect lifecycle: two or more hosts. There are intermediate hosts and a definitive host. E.g.: tenea solium (pig tapeworm).

Question 15

In which 3 groups can you divide metazoa?

Answer 15

You can divide metazoa (helminths, multicellular) into:

• Trematodes (fluke)
• Cestodes (tapeworm)
• Nematodes (roundworm)

This is based on morphology, sex (male&female or hermaphroditic), presence of an alimentary tract

Question 16

What are the differences between protozoa and helminths?

Answer 16

Protozoa:

• Size: 1-100 uM
• Unicellular
• Intra-/extracellular
• Reproduction in host: sexually or asexually
• Infection causes an increase in viral load over time

Helminths:

• Size: mm-meters
• Multicellular
• Hermaphroditic or male&female worms
• Reproduction: eggs or larvae
• Infection results in a stable population

Question 17

What is binary fission?

Answer 17

Replicating by dividing into two.

Question 18

What is schizogony?

Answer 18

During schizogony, the parasite replicates its DNA multiple times, after which replication takes places, making multiple daughter cells. Schizogony is type of asexual reproduction, occurring in some protozoa, in which, after a varying number of nuclear divisions, the cell divides into a number of daughter cells. It is a form of asexual multiple fission.