Eukaryotic Parasites 3: Malaria Flashcards
what causes malaria? transmitted? types?
blood borne infection, transmitted by female Anopheles mosquitos. 2 main types: p falciparum and p vivax. P ovale and P malariae are less common. P knowlesi is only present in macaques in SE ASIA. fatal if untreated. affects brain, lungs, placenta, and other organs….
epidemiological features of malaria?
p falciparum highest prevalence in subsaharan africa. (sahara desert is barrier to viral replication). causes majority of malaria death and disease. p vivax highest prevalence in asia pacific region (many africans have evolved resistance to this strain) young children and pregnant women are at greatest risk of malaria. 500 million cases per year with 300,000 deaths per year.
at which stage in its life cycle does malaria parasite develop? which stage is the immune response directed against?
develops in the liver in hepatocytes and ruptures out. immune system directed against blood stage parasite, involving both humoral and cellular responses.
clinical features of mild vs severe malaria?
Mild (uncomplicated) malaria: majority of cases!
- fever, headache, malaise
- flu like symptoms
Severe malaria:
- severe anaemia
- neurological (convulsions, coma, long term neurological deficits)
- resp distress and metabolic acidosis
- hypoglycaemia, kidney failure, clotting problems
how should malaria be treated?
course of anti malarial tablets and if required, IV fluids, blood transfusion
explain the pathogeneisis of malaria illness
parasite replicates unrestricted in the blood stream.
—>accumulate in vital organs, cause inflammatory response, destroy RBC’s
leads to…..
multi-organ involvement
—>severe anemia, coma, metabolic acidosis
what are the 3 main types of immunity that can develop against malaria?
- all malaria throughout life
- severe malaria early on
- pregnancy between 20-30yrs old
what are the parasite and host factors responsible for the slow development of resistance against malaria?
parasite
-multiple antigenic targets, ++ diversity and antigenic switcing to avoid immune system
host
- inadequate response in children
- poor memory against malaria (induction of memory B and T cells is impaired in malaria)
why are RBC’s an ideal target for malaria?
They have no MHC! malaria is protected from the immune response.
how can the immune system potentiate the adverse effects of malaria?
an excessive pro inflammatory response is associated with severe disease in malaria, largely TNF-alpha driven. Contributes to pathogenesis of malaria.
what role do antibodies have in fighting/impeding malaria pathogenesis?
Ab against merozoites, tagging them to be opsonized or cell mediated inhibition of growth.
Ab against parasite antigens expressed on surfaces of RBC’s. Either flag RBC’s for opsonoziation or blog the parasite surface markers that function to bring in resources needed for parasite to replicate. Also act to prevent infection of RBC’s in the first place if given prophylactically.
why might the immune response against malaria be ineffective?
- Ab to liver stage
- wrong antigen (not essential for invasion/attachment
- right antigen, wrong epitope (unecessary for invasion/attachment)
a vaccine against malaria would target…..
- sporozoite/liver stage
- merozoite stage
NB: vaccines only currently available for P falciparum, (targetting major antigen of sporozoites)
summary of stuff about malaria
