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1

What is Malaria?

It is a parasite of human red blood cells

2

How many people does malaria kill per year? Per day?

How many cases in 2010?

Top paraside killer

- 700,000 – 1.1 million deaths/year
- >2000/day
- 216 million cases in 2010

3

Where do 90% of Malaria deaths occur?

sub-Saharan Africa

4

Which type of mosquito is malaria transmitted by?

Anopheles mosquitoes
(Ann-off-fi-lees)i think..

5

Describe the malaria life cycle

1. Mosquito Stage ->Transmitted to humans (injects sporozoites via bite)
3. Liver stage: hepatocyte invasion (sporozoites infect hypnozoites)
4. Blood stage: liver cells rupture and release merozoites ->inflect red blood cells
5. Asexual Stage (sick/symptomatic)
6. Sexual stage -merozoites produce gametocytes (not symptomatic)
6. Transmission to mosquito (ingests gametocytes via bite)

6

What is a vector?

Vectors are living organisms that can transmit infectious diseases between humans (or from animals) to humans.

7

Which species of the parasite that causes malaria causes the most deaths?

What other species are there?

Plasmodium Falciparum (usually what people are referring to when they talk about malaria)
- causes the most deaths

Plasmodium Vivax
Plasmodium Knowlesi
-can also kill/cause malaria

Plasmodium Ovale
Plasmodium Malariae
- can make you sick but won't kill you

8

What are some characteristics of the mosquito that transmits malaria? (5)

Anopheles mosquitoes:
1. Bite dusk to dawn (not during the day)
2. Only females bite
3. Inactive below 18 degrees celsius
4. Altitude sensitive
5. Don't like cities

9

What are the only effective repellants for anopheles?

What is another effective way to combat anopheles bites?

DEET and picaridin

Permethrin (insecticide)-treated clothes/nets/curtains

10

How has the distribution of malaria changed from the 1900s to present?

The distribution of the species of mosquitoes that transmit malaria has changed significantly and is now very restricted to the tropics

11

How has Malaria affected the human genome?

because of malaria and because it kills so many, it became adaptive to have genes in our genome that cause sickle cell anemia if you have both alleles, but protects you against malaria if you have only one

12

Which species of malaria have an animal reservoir? which do not?

1. falciparum - has animal reservoir
2. all other species - no animal reservoir

13

What is the difference between eradication and elimination?

Which species of malaria could potentially be eradicated?

Eradicate: remove completely

Eliminate: reduce transmission below a threshold

Vivax, Malariae, Ovale, and Knowlesi could all potentially be eradicated (no animal reservoir)

14

Which species of malaria kill the most people?

Which species can also kill?

Falciparum**

Vivax, Knowlesi

15

Which species of malaria will make you sick but not kill you?

Ovale
Malariae

16

What happens when malaria invades the red blood cells?

Severe hemolysis

17

What are the symptoms of Severe hemolysis?

1. Anemia
2. Jaundice
3. Splenomegaly
4. Thrombocytopenia (bleeding)
5. Acute tubular necrosis

18

What is Sequestration?

The red blood cells change form (shape), they can now enter vessels where they are not supposed to go and block them

19

What is cerebral malaria

When sequestration causes obstruction of micro articulations in the brain which can lead to confusion, coma, convulsions, retina bleeding (most important cause of death)

20

What is ARDS

Acute Pulmonary Edema:
it is inflammation of the lungs, this occurs 1-5 days after you think that you are ok, this is a high predictor of death in LIC because in HIC you are generally followed for that afterwards

21

How do malaria complications vary by age and location?

In severe high risk areas, if you survive until age 5 you will probably be ok (develop immunity)

In areas with seasonal transmission -> don't develop immunity and adults will get sick

22

What is the impact of HIV on malaria?

Increased
- Parasitemia
- Clinical malaria
- Severe Malaria
- Antimalarial drug use

Decreased
- Treatment efficacy
- Hemoglobin levels

23

What is the impact of malaria on HIV?

Increased
- Specificity HIV RDTs
- Transient viral load
- HIV transmission

Decreased:
- Transient CD4

Unknown impact on
- Progression to AIDS

24

What tools are available for malaria control?

1. Vector reduction (reducing mosquitos)

2. Bite prevention (bed nets, repellants, clothing)

3. Individual level:
At the sporozoite stage before they reach the liver

Vaccine so that they cannot reach the liver
Primaquine to protect the mosquitoes to reach the liver

During the blood stage to prevent asexual reproduction

Suppressive chemotherapy, vaccines still to be found

Treat at risk pop: pregnant women and infants

During the blood stage to prevent sexual reproduction
- Anti-hypnozoite
- Anti-gametocyte

25

Which repellants are effective?

Less effective?

Not at all effective?

Effective products:
– DEET (use 35-50% solutions)
– Picardin (use 20% solution, only 7% available is US)*
– Permethrin on clothes and bednets

Much less effective:
– Eucalyptus oil, 2% soybean oil

Not effective:
– Citronella, ultrasonic devices, ankle/wristbands, geranium oil, baby oil

26

Where are we with malaria control in 2019?

1. Chronique resistance in 1970s and reversed gains we had made
2. Increase of drug resistance
3. In 2000, the MDGs and other initiatives were launched
4. We have been able to reduce transmission from about ½ from 2000 to 2015

27

What are urgent threats to malaria control?

1. Resistance in mosquitoes
– Pyrethroid resistance now widespread in some areas
– DDT resistance

2. Resistance in Plasmodium – Artemisinin resistance (treatment resistance)

3. Complacency in the face of recent gains

28

Why is artesunate resistance a looming threat?

1. Initially thought to be contained to small pockets SE Asia
2. Now documented to be widespread in SE Asia
3. New foci found in Guyana
4. Looming threat in Africa

29

What is required to eliminate malaria?

Endgame will require specific intensified concerted action despite decreasing cases
– Much more $$ per case averted
– Politically difficult to maintain
– Morbidity of other species, submicroscopic disease