malaria Flashcards
What are the main types of plasmodium causing malaria
P. Falciparum and P. vivax
What organs are predominately affected in malaria
Brain, lungs and placenta
What is the difference in global distribution of P. Falciparum and P. Vivax
Falciparum - mostly central Africa
Vivax - mostly South America and Indonesia
Outcomes of malaria during pregnancy
Low birth weight
Still births
Miscarriage
Which type of plasmodium causes the most disease and which has a dormant liver stage
Most disease - falciparum
Liver stage - vivax
Which type of plasmodium can cross species infect
P. knowlesi
Explain the life cycle of malaria
Sporozoites Injected by Mosquitos –> travels to the liver where they replicate for 7-10 days –> burst out of the hepatocytes as merozoites –> infect red blood cells –> replicate to huge numbers = disease –> parasite becomes sexual form –> taken up again by Mosquitos
Malarial disease is only during which stage of infetion
Blood stage
Is malaria carried in female or male Mosquitos
Female
What are the symptoms of mild uncomplicated malaria
Flu like symptoms - fever, headache and malaise
What are the three main complications of severe malaria
Severe anaemia
Cerebral complications
Respiratory distress and metabolic acidosis
What are the cerebral complications of severe malaria
Convultions
Coma
Long term neurological deficits
What is the treatment for mild malaria
Short course of anti malarial tablets
Need extra drug (primaquine) if infected with P. vivax
What is the treatment of severe malaria
Anti malarials Blood transfusion if required IV saline Supportive treatment Anticonvulsants and anticoagulants if needed
What is the run of the mill anti malarial drug
Artemisinin
What three things contribute to the development of severe malaria
Parasite accumulating in vital organs
Inflammation
Destruction of red blood cells
What are the three main types of immunity against malaria
Immunity against severe malaria during early childhood
Immunity against any malaria
Immunity to malaria during pregnancy
What are there parasite factors that contribute to having such a slow development of immunity against malaria
Multiple antigenic targets
Antigenic diversity
Antigenic variation
What host factors contribute to having such a slow development of immunity against malaria
Inadequate response (especially in young children) Non functional/irreverent immune response Poor development of memory responses
How do antibodies contribute to the immune response for malaria
Neutralisation
Opsonisation for phagocytosis
Complement for lysis
How does the cell mediated response contribute to the immune response to malaria
CD4 cells contribute to the activation of B cells and macrophages
CD8 cells to help combat intracellular pathogens
Activated macrophages
What genetic factors contribute to immunity against malaria
Sickle cell anaemia - heterogenous
Beta-thalassemia
Blood groups
What part of the immune system targets sporozoites
Antibodies and T cells
What part of the immune system targets infected red blood cells
T cells
What part of the immune system targets merozoites
Antibodies
What parts of the immune system target infected red blood cells
Antibodies and T cells
How do antibodies against sporozoites give us some immunity
Binding prevents infection of the hepatocytes
What is the main way in which we provide immune response to the liver phase of malarial replication
Via CD8 T cells
The majority of immune response to malaria occurs at what stage of malarial infection
Blood stage
What are the cell mediated immune responses to the blood stage of malarial infection
- CD4 T cells - for antibody and macrophage activation
- Macrophage action to remove infected red blood cells via the spleen
- IFN-gamma
What are the antibody responses to the blood stage of malaria
- antibodies against merozoites (prevent invasion, and antibody dependent-cell mediated inhibition of parasite growth)
- antibodies against infected RBCs (opsonization for phagocytosis)
what are the three strategies for a malaria vaccine
- action on sporozoites in the liver (antibodies, CD8 T cells blocking development in the liver, blocking entry into the blood)
- action on merozoites (block replication and entry into the blood cells)
- block the sexual stages of the parasite so it cant get into mosquitos
