Protozoa

Question 1

Name the different types of Trypanosoma body plans

Answer 1

Amastigote, choanomastigote, promastigote, opisthomastigote, epimastigote, trypomastigote

Question 2

How do members of the genus Trypanosoma generate movement of the flagellum?

Answer 2

The flagellum is inserted into the cell, and surrounded by kinetosomes (which anchor flagellum). They have a small cluster of DNA in the mitochondria called the kinetoplast.

Question 3

Describe the Trypanosoma body plan: Amastigote

Answer 3

Amastigotes have no protruding flagellum

Question 4

Describe the Trypanosoma body plan: Epimastigote

Answer 4

Flagellum sticks out in about the middle of the cell, with an undulating membrane between it and the cell.

Question 5

Describe the Trypanosoma body plan: Promastigote

Answer 5

Flagellum comes out of the anterior end

Question 6

Describe the Trypanosoma body plan: Opisthomastigote

Answer 6

Flegellum starts in posterior end, runs through body and comes out of the anterior end

Question 7

Describe the Trypanosoma body plan: Trypomastigote

Answer 7

Flagellum sticks out of the anterior end and has an undulating membrane down the whole length of the organism.

Question 8

Flagellated organisms that live in the blood are referred to as ____

Answer 8

Hemoflagellates

Question 9

TRUE OR FALSE: The name Trypanosoma brucei refers to a single organism causing sleeping sickness/Ngana

Answer 9

FALSE, it is a complex of organisms

Question 10

What are the members of the T. brucei complex and what do they all do?

Answer 10

T. b. gambiense: causes west african sleeping sickness (usually just on humans)
T. b. rhodesiense: East african sleeping sickness
T. b. brucei: usually don’t effect humans

Question 11

The chance of dying from African Sleeping Sickness is approximately ____

Answer 11

1/2

Question 12

What are some examples of times where cases of African Sleeping Sickness were highest/lowest in Uganda

Answer 12

Highest - During times of war, immediately after DDT use ceased (especially because of civil war), when other countries nearby refuse to help
Lowest - During the height of DDT use

Question 13

T. brucei is transmitted by _______ flies of the genus _____

Answer 13

tsetse flies, genus Glossina

Question 14

What are the clinical features of T. brucei infection?

Answer 14

3 stages:
Chancre appears at site of infection (red, circular sore)
Hemolymphatic stage - parasites develop in blood or lymph nodes, lymph nodes become swollen and tender (especially axillary lymph nodes and base of neck lymph nodes).
After weeks to months, invasion of the CNS starts (can cross blood brain barrier). Meningoencaphilitic stage occurs. Headaches, sleepingess, abnormal behaviour, loss of consciousness, coma.
Affection is more acute in T. b. rhodesiense (die within 2-6 months), than in T. b. gambiense (die within 1-2 years)

Question 15

Describe the T. brucei life cycle

Answer 15

Parasites ingested by fly through a blood meal from an infected mammal. Parasites multiply in the fly, develop in to procyclic trypanosomes, epimastigotes, metacylic trypanosomes in the insect gut and salivary glands. Take approx. 3 weeks.

Question 16

People infected with T. b. rhodesiense often die of….?

Answer 16

Heart failure, lung failure

Question 17

People infected with T. b. gambiense often die of….?

Answer 17

Coma

Question 18

Why is it that T. b. rhodesiense is often restricted to east africa?

Answer 18

Because the flies prefer to live in the open savannah, and humans die so quickly there is little human-human contact

Question 19

_____ is the time from infection until serious symptoms

Answer 19

Prepatent period

Question 20

How is a T. brucei infection diagnosed?

Answer 20

Microscopic examination of chancre fluid, lymph fluid, blood, bone marrow, or cerebrospinal fluid (late stage).
Can be examined for motile trypanosomes or fixed and stained using Giemsa or Field. Can be concentrated by centrifugation.
ELISA methods are being evaluated by are not sensitive enough for clinical use

Question 21

What can be used to treat T. brucei infections?

Answer 21

Typically Pentavalent antimonials (5 antimony molecules) are used. They often cause neurological issues, especially if they can cross the blood brain barrier. These are highly toxic compounds (There is only a small difference between the therapeutic dose and the toxic dose) that must be administered by a doctor through an IV. They are also quite expensive

Question 22

What deadly treatment method was used for T. brucei infections?

Answer 22

“Trivalent antimonials” (3 molecules of antimony, AKA arsenic). were used and are severely neurotoxic.

Question 23

Why is it that clearing brush in Africa can affect rates of African sleeping sickness?

Answer 23

Female flies have to deposit larva in the shade in the ground, so if there is no shade the larvae will die