Flashcards in Lecture 4 Deck (29)
What is Malaria?
It is a parasite of human red blood cells
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
- 216 million cases in 2010
Where do 90% of Malaria deaths occur?
Which type of mosquito is malaria transmitted by?
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)
What is a vector?
Vectors are living organisms that can transmit infectious diseases between humans (or from animals) to humans.
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
-can also kill/cause malaria
- can make you sick but won't kill you
What are some characteristics of the mosquito that transmits malaria? (5)
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
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
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
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
Which species of malaria have an animal reservoir? which do not?
1. falciparum - has animal reservoir
2. all other species - no animal reservoir
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)
Which species of malaria kill the most people?
Which species can also kill?
Which species of malaria will make you sick but not kill you?
What happens when malaria invades the red blood cells?
What are the symptoms of Severe hemolysis?
4. Thrombocytopenia (bleeding)
5. Acute tubular necrosis
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
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)
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
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
What is the impact of HIV on malaria?
- ￼Clinical malaria
- ￼Severe Malaria
- ￼Antimalarial drug use
- ￼Treatment efficacy
- ￼Hemoglobin levels
What is the impact of malaria on HIV?
- Specificity HIV RDTs
- ￼Transient viral load
- HIV transmission
- Transient CD4
Unknown impact on￼
- Progression to AIDS
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
Which repellants are effective?
Not at all effective?
– 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
– Citronella, ultrasonic devices, ankle/wristbands, geranium oil, baby oil
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
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
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