Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IHO Week 3 > Malaria Module > Flashcards

Malaria Module Flashcards

1
Q

In what areas of the world is malaria endemic?

A

AFRICA

but also part of Asia and Latin America

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The few cases that occur annually in the US are generally from what source?

A

contaminated blood transfusions - malaria is a disease we don’t screen for

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What causes malaria?

A

a protozoa called plasmodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is hemozoin?

A

It’s a crystallized pigment that the plasmodium creates as a byproduct when it eats hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

WHY does the parasite form hemozoin?

A

the first break down product of eating hemoglobin is hematin, which is toxic. So it turns hematin to hemazoin which is nontoxic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is malaria spread?

A

the anopheles mosquito

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What’s the stereotypical histology picture of malaria?

A

A RBC with ring strucutres = trophozoites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the four species of plasmodium we’re concerned about for humans?

A
  1. plasmodium vivax
  2. plasmodium ovale
  3. plasmodium malariae
  4. plasmodium falciparum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which species causes the worst disease/is most deadly? Why?

A

falciparum - it causes the highest parasite burden because it doesn’t care what stage the RBCs are in. Leads to severe anemia - it’s capable of entering the brain and has multi-organ symptoms
very high fatality rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are the three other species less deadly?

A

they don’t cause as high a parasite load, so the anemia is much milder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which two species can cause relapse? How?

A

vivax and ovale

They form hypnozoite forms that lay dormant in the liver for years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What two species are most common? Where?

A 
vivax = everywhere but africa
falciparum = africa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What form is the parasite in when the mosquito injects it into the human?

A

sporozoites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What’s the first cell the sporozoites infect?

A

hepatocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the parasite do in the hepatoctes?

A

proliferates and forms a schizont

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What eventually happens to the schizont?

A

When it’s large enough, it will rupture, releasing the “babies” as merozoites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Merozoites re-enter the blood and infect what cells?

A

RBCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do the merozoites form in the RBCs?

A

trophozoites = the ring structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does the trophozoite develop into?

A

Another schizont with merozoites inside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Some of the merozoites that are released from the schizont will then go to infect other RBCs, but others will do what?

A

Form gametocytes, which will be picked up in the blood by another anopheles mosquito that comes along - then they will undergo sexual reproduction in the mosquito

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How can you differentiate the falciparum species from the others?

A

In the gametocyte stage, they aren’t round like the others - they’re shaped more like a banana

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How can you differentiate vivax and ovale from the other two?

A

vivax and ovale have dark schuffner’s dots in the cytoplasm

23
Q

What two red cell pathologies are caused by a falciparum that leads to blocked capillaries?

A
  1. they form rosettes - an infected RBC surrounded by three healthy RBCs - these clump together and block capillaries
  2. Proteins secreted by the parasite make the outside of the cell all “bumpy” and they exhibit abnormal binding tot he endothelial walls, causing blockage as well
24
Q

What’s the main cause of death with falciparum infection in children?

A

cerebral ischemia

25
Q

What three cytokines are produced in high amounts by infected RBCs?

A

TNF, INF-gamma and IL-1

26
Q

What receptor in particular does the parasite use to enter the RBC?

A

glycophorin

27
Q

What two organs become enlarged in a malarial infection?

A

spleen and liver

28
Q

What color will the liver and spleen turn? Why?

A

gray - because of the hemozoin

29
Q

What are the classic symptoms of malaria?

A

1-2 week incubation
then flu-like illness
focus on the fever! It will relapse and remit at different rates depending on the species

30
Q

Describe the fevers for the following:
falciparum
vivax or ovale
malariae

A

falciparum = quotidian = daily
vivax or ovale - tertian = every 48 hours
malariae = quartan = every 72 hours

31
Q

What are some traits that will lend resistance against malaria to the host?

A

inherited red cell alterations - sickle cell trait, HbC, or different red blood cell antigens (O infected less severely than A and B)

32
Q

People who live in endemic areas often develop partial immune-mediated resistance over time, but how does falciparum evade this?

A

It alters it’s PFEMP protein (the one that makes it bulgy) so the T and B memory cells can’t recognize it

33
Q

How is the diagnosis of malaria made?

A
  1. clinical symptoms plus history of exposure
  2. identificaiton of plasmodia in red cells on a regularly stained blood smear
  3. rapid immunochromatographic tests sometimes used (quicker, but less accurate)
34
Q

WHat are the main considerations in choosing treatments for malaria?

A
  1. which area was visited - chloroquine resistance?
  2. Probability of persistent hepatic forms?
  3. Clinical status of disease?
35
Q

What two species readily develop resistance?

A

vivax and falciparum

36
Q

What drug is always first-line unless you’re in a resistance area?

A

chloroquine

37
Q

Do we have any drugs that work on the sporozoite form?

A

Unfortunately not - most treatment is focused on the asexual RBC stages

38
Q

How does chloroquine work?

A

As the parasite eats hemoglobin, they produces ferriprotoporphyrin (hematin) in the vacuole, which is toxic to the parasite

chloroquine binds to hematin and prevents its conversion to hemozoin, so the plasmodium dies

39
Q

How does chloroquine get its selective toxicity>

A

It reaches MUCH higher concentrations in infected RBCs than in uninfected RBCs

40
Q

What major side effects do you need to consider with acute attack doses of chloroquine?

A

the worst is severe eye damage leading to blindness

also dizzines, HA, itching, vomiting, skin rashes

41
Q

When do we use quinine? Is it more or less toxic than chloroquine?

A

It’s more toxic than chloroquine, but resistance has nor eadily developed, so we use it against chloroquin-resistant falciparum

42
Q

What’s the mechanism of quinine?

A

probalby the same as chloroquine

43
Q

What’s the main side effect of quinine?

A

again - you have to be concerned about vision, but it also causes damage to balance and hearing as well - also tinnitus, nausea, and headache

constellation of symptoms = cinchonism

44
Q

When do we use quinidine?

A

we use it in severe malaria because it can be given IV

45
Q

What’s the main side effect of quinidine?

A

cardiac problems - it’s also used as an anti-arrythmic

46
Q

Mefloquine probably works like chloroquine, but what’s the main side effect that limits its use?

A

neuropsychiatric reactions - hallucinations, depression, disorientation, etc.

47
Q

What drug combo works through depolarizing the parasite’s mitochondria and blocking their DHFR?

A

Atovaquone (the mitochondria) and Proguanil (the DHFR)

48
Q

Why don’t you use the atovaquone-proguanil combo alone in severe malaria?

A

Because the effect onset is slow

49
Q

What’s the limiting side effect in the atovaquone-proguanil combo?

A

GI distress

50
Q

What’s the mechanism of the artemisinins?

A

Hemozoin will interact with the artemisinins and produce ROS that damage the parasite proteins
(may also inhibit a calcium ion ATPase in falciparum)

51
Q

Why don’t we use the artemisinins alone?

A

Because they’re the newest ones and we don’t want bugs to develop resistance to them

52
Q

What drug should you use for vivax or ovale to deal with the hypnozoites in the liver?

A

primaquine - the “radical cure”

53
Q

What’s the mechanism of action of primaquine?

A

We’re not sure - but likely generating ROS or interfering with electron transport

54
Q

What’s the main worrisome side effect you have to watch for with primaquine?

A

hemolytic anemia in people with G6PD deficiency

IHO Week 3 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions