Life cycles in Protozoa

Question 1

Trypanosoma brucei (African sleeping sickness) life cycle

Answer 1

Human stages
1. Tsetse fly takes a blood meal (injects metacyclic trypomastigotes)

2. Injected metacyclic trypomastigotes transform into bloodstream trypomastigotes, which are carried to other sites
3. Trypomastigotes multiply by binary fission in various body fluids
4. Trypomastigotes in blood

Tsetse fly stages
5. Tsetse fly takes a blood meal (bloodstream trypomastigotes are ingested)

6. Bloodstream trypomastigotes transform into procyclic trypomastigotes in tsetse fly’s midgut. Procyclic trypomastigotes multiply by binary fission
7. Procyclic trypomastigotes leave the midgut and transform into epimastigotes
8. Epimastigotes multiply in salivary gland. they transform into metacyclic trypomastigotes

Question 2

Trypanosoma cruzi

Answer 2

Human stages
1. Triatomine bug takes a blood meal (passes metacyclic trypomastigotes in feces, trypomastigotes enter bite wound or mucosal membranes, such as the conjunctiva)

2. Metacyclic trypomastigotes penetrate various cells at bite wound site. Inside cells they transform into amastigotes
3. Amastigotes multiply by binary fission in cells of infected tissues
4. Intracellular amastigotes transform into trypomastigotes, then burst out of cell and enter the bloodstream

Triatomine bug stages
5. Triatomine bug takes a blood meal (trypomastigotes ingested)

6. Epimastigotes in midgut
7. Multiply in midgut
8. Metacyclic trypomastigotes in hindgut

Question 3

What cycles are associated with these stages in the malaria life cycle?

___________ –> Human liver stages
___________ –> Human blood stages
___________ –> Mosquito stages

Answer 3

1. Exo-erythrocytic cycle
2. Erythrocytic cycle
3. Sporogonic cycle

Question 4

What is the sickle cell gene caused by?

Answer 4

by a single amino acid mutation in beta chain of hemoglobin gene

Question 5

What is a protective advantage against malaria?

Answer 5

heterozygote advantage

Question 6

How can you tell the mosquito species Anopheles, Aedes, and Culex apart?

Answer 6

1. Adult- pattern on body
2. different angles in resting positions

Question 7

What two species are associated with Schuffner’s dots?

Answer 7

Plasmodium vivax and Plasmodium ovale

Question 8

Hemoglobin digestion by Plasmodium spp. leads to the production of what?

Answer 8

Heme

Question 9

What are treatments for P. vivax and P. ovale?

Answer 9

Primiquine and Chloroquine

Question 10

What is the treatment for P. malariae?

Answer 10

Chloroquine

Question 11

What is the treatment for P. falciparum?

Answer 11

Artemisinin