Lecture 25: Paratisology II

Question 1

What is the deadliest animal? Why?

Answer 1

Mosquitoes, because they transmit Malaria.

Question 2

What is DALY?

Answer 2

Disability adjusted life years. This means healthy years lost due to disease.

Question 3

What parasitic disease has the highest DALY?

Answer 3

Malaria.

Question 4

Name the 4 major protozoan parasitic diseases.

Answer 4

Malaria, leishmaniasis, African trypanosomiasis, Chagas disease

Question 5

Where is Malaria most prevalent?

Answer 5

In sub-Saharan Africa and Southeast Asia. It is also present in South America and east Asia.

Question 6

Why isn’t Malaria prevalent in North America?

Answer 6

Because of the climate. These parasites can’t survive the winter.

Question 7

Why isn’t Malaria present in northern Africa?

Answer 7

Because it’s a desert environment, so it’s too dry for many insects to survive.

Question 8

Malaria is caused by the parasite […]

Answer 8

Plasmodium

Question 9

Describe the life cycle of plasmodium, including:
a) How and in what form it enters the host
b) Where and it what forms it lives in the host
c) How and in what form it exits the host

Answer 9

a) A mosquito bites the host and injects them with sporozoites.
b) They live in the liver, where they spend a week. They convert to merozoites and infect RBCs, with an asexual cycle in the RBCs.
c) Some merozoites convert to gametocytes, which get taken up by another mosquito.

Question 10

Name the two Nobel prize winners related to Malaria and what they discovered (in the early 1900s).

Answer 10

Charles Laveran - found parasite in blood (cause)
Ronald Ross - found the parasite in mosquito (transmission)

Question 11

How does a plasmodium infected red blood cell differ from a normal red blood cell?

Answer 11

It has a rough appearance because it contains plasmodium proteins.

Question 12

What is the impact of plasmodium on red blood cells? How does this affect bodily function?

Answer 12

It makes them sticky. As more and more RBCs become sticky, it can block blood flow in the capillaries.

Question 13

What is the treatment for malaria?

Answer 13

Artemisinin

Question 14

What was the third nobel prize related to Malaria related to?

Answer 14

It was awarded to Chinese doctor Youyou Tu for the discovery of artemisin for the treatment of Malaria.

Question 15

African Trypanosomiasis is also known as […]

Answer 15

Sleeping sickness

Question 16

African Trypanosomiasis is transmitted by what vector?

Answer 16

The tsetse fly.

Question 17

Why is African Trypanosomiasis also known as sleeping sickness?

Answer 17

When the individual gets infected, the diseases progresses into the nervous system, which causes them to become sleepy.

Question 18

African Trypanosomiasis is caused by the parasite […]

Answer 18

Trypanosome Brucei

Question 19

Describe the life cycle of Trypanosome Brucei:
a) How and in what form it enters the host
b) Where it lives in the host
c) How and in what form it leaves the host

Answer 19

a) Enters through Tsetse fly bite
b) Trypanosome Brucei lives and reproduces in the blood, outside of blood cells.
c) A tsetse fly bites the individual and takes up the trypanosomes.

Question 20

Trypanosomes replicate in the […] by […]

Answer 20

Blood plasma, binary fission

Question 21

What are the two types of trypanosomes? Where are they found?

Answer 21

Trypanosome brucei: Africa
Trypanosome cruzi: South America

Question 22

How long have Trypanosomes existed?

Answer 22

For 200 million years. They likely infected dinosaurs.

Question 23

How does the appearance of T. brucei in the blood compare to that of T. cruzi?

Answer 23

T. brucei have a more corkscrew shape. T. cruzi have a very prominent mitochondria with a lot of DNA.

Question 24

Chagas disease is caused by the parasite […]

Answer 24

Trypanosome cruzi.

Question 25

Chagas disease is transmitted by what vector?

Answer 25

A beetle known as Triatomine (assassin bug).

Question 26

Describe the life cycle of trypanosome cruzi:
a) How and in what form it enters the host
b) Where and it what form it lives in the host
c) How and in what form it leaves the host
including the major forms it takes.

Answer 26

a) The host is bitten by the Triatomine and trypomastigotes enter.
b) Trypanosomes turns into amastigotes and live in muscle cells. They then leave muscle cells and enter the blood in the form of Trypomastigotes.
c) Trypomastigotes are taken up by Triatomine.

Question 27

Which organs are typically affected by Trypanosome cruzi?

Answer 27

The esophagus, colon, and heart.

Question 28

What is the consequence on the body of carrying trypanosome cruzi for many years?

Answer 28

You eventually end up with megaoesophagus, megacolon, and especially cardiomyopathy

Question 29

Where is Chagas disease found?

Answer 29

Nearly all cases originate in South America. However, cases can also get exported to other countries via travel.

Question 30

What are the two types of leishmaniasis?

Answer 30

Cutaneous and visceral

Question 31

What parasite causes leishmaniasis?

Answer 31

Leishmania donovani

Question 32

Where is cutaneous leishmaniasis typically found?

Answer 32

Northern Africa, the middle east, south America

Question 33

Where is visceral leishmaniasis typically found?

Answer 33

South America, east Africa, southeast Asia

Question 34

Which form of leishmaniasis is more common?

Answer 34

Cutaneous (300 million cases) is more common than visceral (50 million cases).

Question 35

Describe the difference between visceral leishmaniasis and cutaneous leishmaniasis.

Answer 35

Cutaneous leishmaniasis is not deadly and usually self-heals. It just leads to skin lesions from the immune system response and leaves scars.
Visceral leishmaniasis is deadly if not treated, as the parasite enters the visceral organs (liver, spleen, bone marrow).

Question 36

Leishmania is transmitted by the vector […]

Answer 36

Sandfly.

Question 37

Describe the life cycle of leishmania:
a) How and in what form it enters the host
b) Where and in what form it lives in the host
c) How and in what form it exits the host

Answer 37

a) The sand fly bites the host and injects them with promastigotes.
b) The promastigotes replicate inside macrophage cells, where they convert into amastigotes. Eventually, our macrophages burst and the amastigotes go into the blood.
c) Amastigotes get picked up by another sandfly.

Question 38

Describe how the reservoir of leishmania affects the development of leishmaniasis.

Answer 38

When humans are the initial host, it usually causes visceral leishmaniasis. When the initial host is an animal and then that bug gets transmitted to a human, it typically causes cutaneous leishmaniasis.

Question 39

Visceral leishmaniasis can be treated using […]

Answer 39

Ambisome

Question 40

Is ambisome effective as a treatment?

Answer 40

Generally yes. It only requires one dose and has a cure rate of 95%.

Question 41

What is PKDL?

Answer 41

Post kala-azar dermal Leishmaniasis. It sometimes occurs after people are cured of visceral leishmaniasis.

Question 42

What is the probability of the development of PKDL?

Answer 42

10-25%

Question 43

What happens when someone develops PKDL?

Answer 43

The parasite deposits itself in the skin and creates small spots containing amastigotes. This is harmless to the individual, but we are unsure whether they are reservoirs for transmission.