Lecture 19 - Malaria Epidemiology Flashcards
What is life expectancy?
Life expectancy is the defined as the number of years a newborn child would live if current mortality patterns were to stay the same
What is special about HIV and Malaria?
HIV and Malaria are important because they are caused by a single pathogen.
Taxonomic classification of Malaria
Phylum: Apicomplexa
Genus: Plasmodium
5 species infect Humans: P.falciparum (main one), and P. vivax
Many other species infect animals
single celled protozoan parasite, all apixomplexa invade cells like viruses
Malaria is more common just ___ and ___ of the Equator
North and south
where it becomes more and more tropical, malaria more common because their life cycle extends all year round, winters stop them breeding
What is another factor that raises the malaria prevalence in countries just around the equator?
The high incidence of malaria in the tropics can also be attributed to factors such as poverty, lack of access to healthcare, and limited resources for disease prevention and control. These factors are often more prevalent in tropical regions, where there may be limited infrastructure and resources to support public health interventions.
Why is developing immunity to malaria a problem for disease transmission?
In areas where malaria is endemic, people may develop partial immunity to the disease over time. This can contribute to a higher prevalence of the disease in certain regions, as individuals with partial immunity may experience milder symptoms or may be asymptomatic carriers of the disease, making it more difficult to control its spread.
What are the four species of Plasmodium that infect humans?
P. falciparum
P. vivax
P. ovale
P. malariae
Which three tissues can Plasmodium infect?
What is different about the pathogen at this time?
The insect
The liver
Erythrocytes
It is the same pathogen, i.e. the DNA is the same, however there are morphological differences in the parasite.
Why is malaria a big obstacle to further human development ?
- Close to the #1 infectious cause of child mortality
- Access to available interventions remains poor
- Drug and insecticide resistance rife
- Poor predictors of severe malaria
- No widely available vaccine and need new drugs
What is seen in South America in terms of malaria?
High levels of disease, but less burden of death.
This is because P. vivax is the main species in this area
This species is less fatal
Describe the economic impact of Malaria
Financial burden:
* Bed nets
* Work and School absenteeism
* Represents 10% of annual spending in Africa
What is the vector of the malaria parasite?
Anopholes mosquito
What is the relationship between malaria and sickle cell anemia?
- Individuals with sickle cell trait or sickle cell disease have a reduced risk of severe malaria compared to individuals without the sickle cell gene.
- The protective effect of sickle cell against malaria is thought to be related to the abnormal shape of sickle cells. These misshapen cells may make it more difficult for the malaria parasite to invade and multiply within red blood cells..
List the stages of the life cycle of the malaria parasite
What type of reproduction is occurring at each stage?
- Mosquito stage – sexual reproduction
- Liver stage – asexual reproduction
- Blood-stage – asexual reproduction, major amplification stage
What is the lifecycle of P.falciparum in malaria?
- Infection: The lifecycle begins when a female Anopheles mosquito infected with P. falciparum bites a human host and injects the sporozoites (infective form) of the parasite into the bloodstream. Injected sporozoites enter hepatocytes via the skin
- Liver stage: The sporozoites travel to the liver, where they infect liver cells and multiply to form thousands of merozoites. ASEXUALLY
- Blood stage: The merozoites are released into the bloodstream, where they infect red blood cells and multiply rapidly. ASEXUALLY. During this stage, the infected red blood cells may stick to the walls of blood vessels and cause damage to the host’s tissues.
- Ring stage: The first visible stage of the parasite in the red blood cells is the ring stage, where the parasite is surrounded by a ring-shaped structure.
- Trophozoite stage: As the parasite matures, it progresses to the trophozoite stage, where it continues to multiply and begins to consume hemoglobin from the host’s red blood cells.
- Schizont stage: The parasite then progresses to the schizont stage, where it forms many daughter merozoites inside the infected red blood cell.
- Rupture and reinfection: Eventually, the infected red blood cell ruptures and releases the daughter merozoites into the bloodstream, where they can infect new red blood cells and continue the cycle of infection.
Gametocytes form in the blood and are taken up by a feeding mosquito
What are sporozoites?
Haploid
Generated by meiosis (sexual reproduction) in the mosquito
This is what infects the human