Malaria Flashcards
What are the two main types of malaria?
P. falciparum and P. vivax
Where is P. falciparum worst in the world?
sub saharan Africa
Where is P. vivax the worst?
asia pacific and south and central america
What are the obstacles to combating malaria?
no vaccine, drug resistance, insecticide resistance, plus economic, social and political factors
Which type of malaria causes the most severe type of malaria?
P. falciparum
Which type of malaria has a dormant liver stage?
P. vivax
What transmits malaria?
female anopheles mosquitos
How long does P. falciparum incubate in the liver for?
7-10 days
During what stage of the life cycle does malaria cause disease?
when there are high numbers of parasites in the blood stream - the liver stage is asymptomatic
What are sporozoites?
the stage of the life cycle that infects the human
What are merozoites?
the stage of the life cycle that infects the blood stream
What does the immune response target?
merozoites
What are the clinical features of uncomplicated (mild) malaria?
flu like illness with fever, headache, malaise
What are the clinical features of severe malaria
severe anaemia, cerebral malaria (coma, convulsions), respiratory distress and metabolic acidsosis, hypoglycaemia, kidney failure, blood clotting problems
What percentage of cases are severe malaria?
5%
What is the treatment of mild malaria?
short course of anti malarials
What is the treatment of mild malaria caused by P.vivax
14 day course of anti malarials - because of the doormant liver stage
What is the treatment of severe malaria?
anti malarials and supportive care
What causes the problems in the body from malaria?
parasites accumulating in vital organs, inflammatory response, destruction of RBCs
What are the three types of immunity to malaria?
immunity that prevents severe malaria, immunity that prevents any malaria and immunity that protects against malaria in pregnancy
Why is there slow develop of immunity to malaria?
multiple antigenic targets, antigenic diversity, antigenic variation
What genetic factors help in resistance to malaria?
sickle cell, alpha-thalassemia, blood groups
What acquired immune response is there against sporozoites?
antibodies and T cells - the antibodies prevent infection of hepatocytes
What acquired immune response is there against infected hepatocytes?
T cells
What acquired immune response is there against merozoites?
antibodies - inhibit invasion of RBCs
What acquired immune response is there against infected RBCs?
antibodies (because parasite antigens are expressed on the cell surface) and CD4 T cells
Which cytokine in the blood stage is associated with protection?
IFNgamma
Which cytokine in the blood stage is associated with severe disease?
TNFalpha
What are the different types of vaccines against malaria?
vaccines that target sporozoites, vaccines that target merozoites or vaccines that target the sexual stages to stop transmission
What is the RTS,S vaccine?
a vaccine which targets the major antigen on sporozoites
What is the efficacy of the RTS,S vaccine and how long does it last?
30-50% and only lasts 2 years
Why is it difficult to develop a vaccine that targets merozoites?
because there are so many different antigens
Are there vaccines available for P. vivax?
no
