Plasmodium Flashcards
How many people are infected by malaria each year?
More people dying now than 30 years ago
1.5-2.7 million,, mostly children under 5
1 child dies every 12 seconds
10% of the worlds population will suffer a clinical attack each year
How long to malaria symptoms take to manifest themselves?
Tend to appear 10 days to 4 weeks after the initial bite
In some cases however, depending on the type of parasite it can take up to a year before symptoms start to show
What are the symptoms of benign malaria?
Flu like symptoms - fever - aches - chills - nausea and vomiting - diarrhoea These symptoms can last for several weeks if no medication is taken but usually disappear within a few days with proper treatment
What are the symptoms of malignant malaria?
Plasmodium falciparum parasite Symptoms like benign malaria Lead to severe complications - liver failure - cerebral malaria - shock
What are the three distinct invasive forms in plasmodium?
Sporozoite - transmitted from the mosquito into the intermediate host
Merozoite - Comes out of liver and invades the red blood cells (penetration takes around 20 seconds)
Ookinete - invades the intestinal cell wall of the mosquito
What are the four distinct steps of invasion in Plasmodium?
Initial contact - Random collisions
Reorientation/Deformation - have to reorientate themselves so apex and plasma membrane form tight junction
Junction Formation
Entry - resides within a parasitophorous vacuole
What is the protein that allows Plasmodium to attach to red blood cells?
Merozoite surface protein-1 (MSP-1)
What is the function of micronemes, rhoptries and dense granules in Plasmodium invasion?
Micronemes - secreted first by plasmodium, sticky protein to hold the parasite in place
Rhoptries - Secretes enzymes to prepare the vacuole for the parasite to reside within
Dense granules - means of communication between the parasite and the cell to provide nutrients etc
Why is it so hard to find effective vaccines for parasites?
Parasite - High mutation rates - Clones with different drug sensitivities Drug - Underdosage - Pharmacokinetics (refers to the movement of the drug in, through and out the body) Host - immunity - metabolic similarities Vector - Degree of genetic exchange - Sexual cycle
What is a common malarial drug and what are the modes of action that have been proposed in association with it?
Arteminisin - isolated from the plant Artemisia annua
4 different models for mode of action proposed
1 - interferes with heme detoxification pathway
2 - Induces alkylation of the translationally controlled tumour protein (PfTCTP)
3 - Inhibit the sarco/endoplasmic reticulum membrane calcium ATPase 6 (PfATPase)
4 - Interfere with the Plasmodium mitochondrial functions
It is possible that different mechanisms might play a role depending on arteminisin derivative, strain, parasite stage and experimental settings
How many different species of plasmodium are there? How many affect humans? How is it transmitted and what are the clinical manifestations?
\+200 different species At least 10 infect humans Transmitted by female anopheles mosquito Clinical manifestations - cerebral malaria - Splenomegaly - Progressive anaemia
