Lecture 16 + 17 - Malaria Flashcards
Age group most represented in malaria deaths
Children under 5
Phylum of malaria
Apicomplexia
Genus of malaria
Plasmodium
Plasmodium species that infect humans 1) 2) 3) 4)
1) Falciparum
2) Vivax
3) Ovalae
4) Malariae
Primate - human plasmodium pathogen
Plasmodium knowlesi
How does plasmodium gain access to hepatocytes?
Kupfer cell
3 places where plasmodium live
Mosquito, human hepatocytes, human erythrocytes
Example of the strength of anti-malarial selective pressure
Sickle-cell anaemia alleles are maintained in sub-Saharan Africa, as being heterozygous for this reduces susceptibility to malaria
Difference in P. vivax and P. falciparum infection
Vivax causes more severe morbidity, but is less likely to kill
Number of malaria deaths per year
~650,000
What are the gold crystals observed in malaria-infected erythrocytes?
Haemozin
Parasite eats haemoglobin, but haem is toxic.
Crystallises haem to haemozoin
Malaria definitive host
Mosquito (where sexual reproduction of gametocytes occurs)
Why are malarial infections comparable between Latin America and sub-Saharan Africa, but sub-Saharan Africa has much higher mortality rates?
P. vivax more common in Latin America.
P. falciparum more common in sub-Saharan Africa
Estimated number of malaria cases per year
300 - 500 million
Amount of household spending on malaria in Africa
Estimated 10% of household spending (mosquito nets, medication ,etc)
P. falciparum life cycle 1) a, b, c 2) a, b 3) a, b 4)
1) Mosquito stage (in mosquito gut)
a) Gamete
b) Zygote
c) Ookinete
MOSQUITO BITES HUMAN
2) Hepatocyte stage
a) Sporozoites infect hepatocytes
b) Merozoites form, exit hepatocytes
3) Blood stage
a) Merozoites infect erythrocytes, divide rapidly
b) Gametocytes form
4) Mosquito ingests gametocytes from human host, sexual reproduction in mosquito
When does malaria cause illness?
During merozoite stage
Hepatocyte stage is asymptomatic
Number of infected erythrocytes directly after hepatocyte stage Vs number of infected erythrocytes after merozoite expansion
10^3 infected erythrocytes Vs 10^11 infected erythrocytes
What does merozoite release coincide with?
Periodic fever, cytokine storm
Basic overview of three stages of malarial infection
Mosquito stage - Sexual reproduction
Hepatocyte stage - Asexual reproduction
Erythrocyte stage - Asexual reproduction, major amplification stage
Where does the sexual stage occur, and for how long?
1 - 2 weeks in female Anopheles mosquito
How long does it take for injected sporozoites to enter hepatocytes from skin?
~30 minutes
How long does the asexual liver stage last for?
~1-2 weeks
How long after infection does disease occur?
~1 month
How long does the asexual erythrocyte stage last for?
~2-3 days, is quite synchronous
Symptoms of malaria
Fever, chills, anaemia, coma
Proportion of malaria deaths caused by P. falciparum
95%
How does P. vivax cause relapsing malaria?
Hypnozoites in the liver