Block E Lecture 3: Protozoan Cell Biology and Disease Part C: Blood and Tissue Parasitic Infections

Question 1

What is Leishmania?

Answer 1

A flagellated protozoan
(Slide 34)

Question 2

What does leishmania cause?

Answer 2

Cutaneous, mucocutaneous or visceral leishmaniasis
(Slide 34)

Question 3

How is leishmaniasis transmitted?

Answer 3

By sand fly bite
(Side 34)

Question 4

What cell does leishmania infect and grow in?

Answer 4

Macrophages
(Slide 34)

Question 5

How is leishmaniasis diagnosed?

Answer 5

Microscopy of tissue specimen, PCR or serology
(Slide 34)

Question 6

What is serology?

Answer 6

When you look for certain antibodies to determine whether a person has been infected with a pathogen
(Slide 34)

Question 7

What occurs in the human stage of the life cycle of Leishmania ?

Answer 7

Female sandflies transfer promastigotes when feeding on human blood. These promastigotes are then phagocytised by macrophages and other types of mononuclear phagocytic cells. Promastigotes then transform in these cells into amastigotes which multiply by simple division and infect other mononuclear phagocytic cells. Sandflies then become infected by ingesting cells when they feed on blood
(Slide 36)

Question 8

What occurs during the sandfly stage of the life cycle of Leishmania?

Answer 8

Sandflies take up cells infected with amastigotes when they feed on human blood. These amastigotes then transform into promastigotes and develop in the guy before migrating to the proboscis (the mouthparts which they use to pierce skin in order to feed on blood)
(Slide 36)

Question 9

What form of leishmaniasis does leishmania mexicana cause?

Answer 9

Cutaneous leishmaniasis
(Slide 37)

Question 10

What does cutaneous leishmaniasis form on the skin?

Answer 10

Nodules and ulcers
(Slide 37)

Question 11

How are all forms of leishmaniasis treated?

Answer 11

With pentavalent antimonial compounds, amphotericin B or miltefosine
(Slides 37, 38 and 39)

Question 12

What form of leishmaniasis does leishmania brasiliensis cause?

Answer 12

Mucocutaneous
(Slide 38)

Question 13

What occurs in mucocutaneous leishmaniasis?

Answer 13

The parasite destroys mucosa and cartilage of the mouth, nose and throat
(Slide 38)

Question 14

What form of leishmaniasis does leishmania donovani cause?

Answer 14

Visceral leishmaniasis (VL)
(Slide 39)

Question 15

What occurs in visceral leishmaniasis?

Answer 15

The parasite travels to internal organs, causing damage to the liver, spleen and bone marrow
(Slide 39)

Question 16

What can occasionally occur after an individual recovers from visceral leishmaniasis?

Answer 16

Relapse of the disease
(Slide 39)

Question 17

What are the 2 subspecies of trypanosome brucei?

Answer 17

T. brucei gambiense
T. brucei rhodesiense
(Slide 40)

Question 18

What does trypanosoma brucei cause?

Answer 18

African sleeping sickness (also known as human African trypanosomiasis or HAT)
(Slide 40)

Question 19

How is African sleeping sickness (AKA Human African Trypanosomiasis or HAT) transmitted?

Answer 19

By the bite of the tsetse fly
(Slide 40)

Question 20

Where does the parasite multiply in African Sleeping Sickness?

Answer 20

In the blood
(Slide 40)

Question 21

What occurs in stage I of African Sleeping Sickness?

Answer 21

An intermittent fever
(Slide 40)

Question 22

What occurs in stage II of African Sleeping Sickness and what does it lead to?

Answer 22

Invasion of the CNS occurs which leads to headaches, somnolence (strong desire for sleep), abnormal behaviour, lethargy (lack of energy and enthusiasm), loss of consciousness and coma
(Slide 41)

Question 23

How is African Sleeping Sickness diagnosed?

Answer 23

By spinal puncture (used to collect cerebrospinal fluid) and microscopy of cerebrospinal fluid
(Slide 41)

Question 24

How is African Sleeping Sickness treated?

Answer 24

With suramin, melarsoprol, pentamidine or eflornithine
(Slide 41)

Question 25

What occurs in the mammalian stage of the life cycle of Trypanosoma brucei?

Answer 25

An infected tsetse fly injects metacyclic trypomastigotes into the skin tissue when it feeds on blood. The parasites enter the lymphatic system and pass into the bloodstream. Inside the host they then transform into bloodstream trypomastigotes which are carried to other sites throughout the body and reach other body fluids where they replicate via binary fission. Tsetse flies then become infected with bloodstream trypomastigotes when they feed on mammalian blood
(Slide 42)

Question 26

What occurs in the tsetse fly stage of the life cycle of Trypanosoma brucei?

Answer 26

In the fly’s midgut, the parasites transform into procyclic trypomastigotes and multiply by binary fission. They then leave the midgut and transform into epimastigotes. These epimastigotes then reach the fly’s salivary glands and multiply again by binary fission. They then infect mammals with these when feeding on their blood.
(Slide 42)

Question 27

What disease does trypanosome cruzi cause?

Answer 27

Chagas’ disease (American trypanosomiasis)
(Slide 43)

Question 28

How is chagas’ disease transmitted?

Answer 28

By bites and defaecation of the “kissing bug” (triatomine bug)
(Slide 43)

Question 29

What does the parasite affect in Chagas’ disease

Answer 29

The heart, gastrointestinal tract and CNS
(Slide 43)

Question 30

How is Chagas’ disease diagnosed?

Answer 30

By microscopy of tissue samples or serology
(Slide 43)

Question 31

How is Chagas’ disease treated?

Answer 31

With nifurtimox (Lampit) and benznidazole (Radanil)
(Slide 43)

Question 32

What occurs in the Mammalian stage of the life cycle of Trypanosoma cruzi?

Answer 32

Triatomine bug feasts on blood and releases trypomastigotes in its faeces near the site of the bite wound. The trypomastigotes then enter the host through the bite wound or intact mucosal membranes. The trypomastigotes then invade cells near the inoculation site where they differentiate into intracellular amastigotes. These then multiply by binary fission and differentiate into trypomastigotes which then infect cells from a variety of tissues and can then transform back into intracellular amastigotes in new infection sites. The triatomine bug can then become infected by feeding on infected blood which contains circulating parasites
(Slide 44)

Question 33

What occurs in the triatomine stage of the life cycle of Trypanosoma cruzi?

Answer 33

The triatomine bug becomes infected when it feeds on mammalian blood containing circulating parasites. Ingested trypomastigotes then transform into epimastigotes in the bug’s midgut, and these then multiply and differentiate in the midgut and then differentiate into infective metacyclic trypomastigotes in the hindgut. The bug can then infect a human or other mammal during a blood meal
(Slide 44)