Introduction to parasitology

Question 1

Define a parasite

Answer 1

An organism that exploits another organism for the purpose of staying alive

Question 2

What are the advantages of being a parasite?

Answer 2

• Protection from hostile conditions
• Provided with nutritional needs
• Can travel great distances and focus on reproduction

Question 3

What are the disadvantages of being a parasite?

Answer 3

• Obliged to travel with host
• Ingenuity to enter host and survive defence mechanisms
• Finding an ideal tissue
• You die if the host dies
• Need to move/exit to spread

Question 4

What are the 2 types of parasite?

Answer 4

1. Protozoans - unicellular eukaryotes with at least one mobile stage
2. Metazoans - multicellular eukaryotes

Question 5

What are the 2 life stages of a protozoan?

Answer 5

1. Trophozoite - active growing stage of a parasite

2. Sporozoite - Motile infective stage resulting from sporogeny of dormant cycles

Question 6

What 4 ways can a parasite enter an organism?

Answer 6

1. Ingestion
2. Arthropod bite
3. Transplacental penetration
4. Organism directed penetration

Question 7

Describe amoebic dysentery

Answer 7

• can be invasive intestinal or invasive extraintestinal
• occurs by ingestion of mature cysts
• Trophocytes produce cysts which are passed through faeces and can survive weeks in the environment, however killed by boiling

Question 8

How is giordia lamblia transmitted and what does it affect?

Answer 8

• Cysts can survive for several months in water and can also be ingested in food
• Directly affects small intestine to produce watery diarrhoea

Question 9

Describe Leishmania

Answer 9

• Tryponosomatid which is unicellular, lacks cilia and has a singular flagellum
• Causes ulcers, tissue damage, fever, organ damage and emaciation
• Sand fly vector

Question 10

What are the syntoms of african sleeping sickness and what is it caused by?

Answer 10

• Begins with fever, headaches, joint pains, lymph node swelling. However when blood-brain barrier is crossed sleeping pattern becomes confused leading to mental deterioration, coma and death
• Vector is Tsetse fly which infects blood and CNS, belived to have an animal resevoir

Question 11

What is responsible for malaria?

Answer 11

Blood stage parasites