2591368
Description
Mind Map by Lucy MacDonald, updated more than 1 year ago
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Created by Lucy MacDonald
almost 11 years ago
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Malaria
- What is Malaria?
- mosquito borne infectious disease
- only females feed on blood
- larvae require still, stagnant water
- only females feed on blood
- caused by the parasitic protozoan Plasmodium
- 300-500 million cases per year in world
- been around for 10,000yrs
- mosquito borne infectious disease
- Life Cycle
- shizogony = division of nuclei into thousands
- no cytoplasm division
- cell membrane then develops
- no cytoplasm division
- (1) During a blood meal, a malaria-infected
female Anopheles mosquito inoculates
sporozoites into the human host
- (2) Sporozoites infect liver cells
- (3) Maturation into Shizonts
- shizogony
- shizogony
- (4) Shizonts ruptures to release merozoites
- Sporozoites > Shizonts > Merozoites > Trophozoites
(Ring Stage) > Asexual Replication > Gametocytes >
Zygote > Oocyst > Sporozoites
- (5) Merozoites infect RBC
- (6) Develop into (ring stage) Trophozoites
- asexual replication within erythrocytes causes
maturation into shizonts again which rupture to
release more merozoites
- asexual replication within erythrocytes causes
maturation into shizonts again which rupture to
release more merozoites
- (7) Some parasites differentiate into gametocytes
- (8) Another female mosquito comes along,
takes blood meal while ingesting
gametocytes
- sporogonic cycle within mosquito
- eventually producing sporozoites and infecting new host
- eventually producing sporozoites and infecting new host
- sporogonic cycle within mosquito
- shizogony = division of nuclei into thousands
- Malarial Fever
- caused by haemozoin
- disposal product formed from digestion of blood
- known as malarial pigment
- attractive target for drug
development
- difficult due to antigenic variation
- difficult due to antigenic variation
- disposal product formed from digestion of blood
- parasites digest haemoglobin
to release free haem
- free haem is toxic so it is converted to
insoluble crystalline form - haemozoin
- free haem is toxic so it is converted to
insoluble crystalline form - haemozoin
- when RBC's rupture,
haemozoin leaks and
causes fever of host
- fever pattern
corresponds to
erythrocyte
rupture and
merozoite
invasion
- caused by haemozoin
- Different Species
- Plasmodium Vivax
- same as ovale
- same as ovale
- Plasmodium Ovale
- benign tertian - peaks every 48 hours
- benign tertian - peaks every 48 hours
- Plasmodium Falciparum
- malignant tertian -
peaks every 48 hours
- malignant tertian -
peaks every 48 hours
- Plasmodium Malariae
- benign quartan malaira -
peaks every 72 hours
- benign quartan malaira -
peaks every 72 hours
- Plasmodium Vivax
- Antigenic Variation and Sequestration
- expression of variant
antigens on surface of
infected RBCs
- immune evasion strategy
- no mutation required
- rate of change
around 1-2%
per division
- 40-50 variant genes per clone of parasite
- 40-50 variant genes per clone of parasite
- e.g. VAR genes
- responsible for
encoding PfEMP-1
family of proteins
- inserted
into
surface
of RBC
- also allow for
sequestration
in brain by
adhering to
endothelial
cells of
capillaries
- inserted
into
surface
of RBC
- in P.falciparum
- responsible for
encoding PfEMP-1
family of proteins
- immune evasion strategy
- sequestration =
adherence of infected
erythrocytes containing
late developmental
stages of the parasite
(trophozoites) to the
endothelium of
capillaries and venules
- expression of variant
antigens on surface of
infected RBCs
- Genetic Resistance
- mutations in haemoglobin genes (haemoglobinopathies)..
- Thalassaemia a & b
- 'sea blood'
- 'sea blood'
- sickle cell anaemia
- Thalassaemia a & b
- Duffy -ve
- antigen located on
RBC which can
function as the
receptor for plasm.
parasite
- allows parasite entry to cell
- if duffy negative, parasite cannot infect RBC
- if duffy negative, parasite cannot infect RBC
- allows parasite entry to cell
- antigen located on
RBC which can
function as the
receptor for plasm.
parasite
- certain HLA alleles (MHC)
- encode proteins involved in antigen presentation
- encode proteins involved in antigen presentation
- Glucose-6-phosphate Dehydrogenase Deficiency
- G6PD is an enzyme involved with glucose production in RBC
- G6PD is an enzyme involved with glucose production in RBC
- mutations in haemoglobin genes (haemoglobinopathies)..
- Malaria + the Placenta
- infected RBC can
sequester in placenta
aswell as in brain
- causes still birth
- causes still birth
- ultrasound scans
show diameter of
foetus head is signif.
smaller with malaria
infection
- if infection is well treated effect is seen to be resolved by birth
- if infection is well treated effect is seen to be resolved by birth
- infected RBC can
sequester in placenta
aswell as in brain
- Treatments + Prevention
- Vector Control
- less mosquitos around to transmit
- 'flowerpot inspectors'
- less mosquitos around to transmit
- bed nets
- prevent biting
- covered in insecticides
- prevent biting
- possible vaccines
- prophylactic drugs
- insanity?
- insanity?
- anti-malarial drugs
- quinine (cinchona tree bark in peru)
- chloroquinine
- artemesin (chinese herb)
- kills ring stage
- predates quinine
- kills ring stage
- quinine (cinchona tree bark in peru)
- Possible P. falciparum vaccination?
- this species relies on single basign receptor on
surface of RBC to invade cell and does so by
attaching a RHS protein to the receptor
- protein ligand is not polymorphic, vaccine containing RHS protein antibody?
- protein ligand is not polymorphic, vaccine containing RHS protein antibody?
- this species relies on single basign receptor on
surface of RBC to invade cell and does so by
attaching a RHS protein to the receptor
- Vector Control
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