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what type of organism is plasmodium?
protozoa
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what are the 4 species of plasmodium?
- falciparum
- ovale
- vivax
- malariae
- knowlesi
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what does plasmodium need to do in order to complete their life cycle?
must pass through both hosts to complete the life cycle
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what are the 2 types of reproduction done by the plasmodium and where?
- sexual in mosquito (gametogony)
- asexual in humans (schizogony)
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why is it the FEMALE anopheles mosquito that causes malaria?
females need to such blood to get iron
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describe the life cycle of malaria
- 1. female anopheles mosquito bites human
- 2. sporozoites pass into the blood to the liver
- 3. in hepatocytes: asexual reproduction - up to 1 month, form SCHIZONT which bursts resulting in release of MEROZOITES into blood = produces first symptoms of FEVER
- 4. merozoites infects RBC to further reproduce asexually
- a) trophozoite forms in RBC looks like ring
- b) schizont forms in RBC
- c) merozoites divide in RBC which bursts and releases more merozoites
- 5. each release of M creates cyclical SPIKES IN FEVER that characterise malaria
- 6. some M develop into gametocytes so human host becomes INFECTIOUS TO MOSQUITOES
- 7. mosquito bites human and human gametocyte into mosquitos gut where SEXUAL REPRODUCTION to create sporozoites which migrate into salivary glands
- 8. ready to be introduced into the next human bitten
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what is plasmodium FALCIPARUM also known as and why?
- MALIGNANT: can be fatal, higher morbidity and mortality
- TERTIAN: as fever on day 1, 3…
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why does falciparum have a higher parasitaemia than other plasmodial species?
- it has the ability to infect red blood cells of all ages
- compared to other plasmodium species
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which is the least common plasmodium? and how often fever? name>
- malariae
- quartan ie fever on d1, d4
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what are the 2 benign tertian malarias?
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what happens to RBC infected with falciparum and what can this lead to?
- RBC infected with falciparum are more sticky
- tendency to occlude small blood vessels
- cause anoxic damage to viral organs
- in brain = cerebral malaria
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which plasmodiums have a fever cycle of 48 hours?
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which plasmodium has a fever cycle of 72 hours?
malariae
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which RBC does falciparum infect?
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which RBC does ovale and vivid infect?
reticulocytes
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which RBC does malaria infect?
older cells
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what is the dormancy site for falciparum?
none
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what is the dormancy site for oval?
liver
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what is the dormancy site for vivid?
liver
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what is the dormancy site for malaria?
blood
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which plasmodium relapse after successful treatment?
- ovale
- vivax
- malariae
- (NOT falciparum)
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what is the mortality of each plasmodium?
- 20% for falciparum
- very low for the rest
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what may pts with malaria notice in their urine?
dark due to haemolysis
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what are the symptoms of malaria?
- fever (cyclical so may not have it when you see the pt)
- rigors
- headache
- myalgia, arthralgia
- NVD
- weakness
- DARK URINE
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what are the signs of malaria?
- fever
- jaundice - haemolysis
- pallor - anaemia as destroyed RBC
- splenomegaly - due to broken down RBC, can be massive with p.malariae as chronic infection
- hepatomegaly
- altered consciousness - sticky RBC so anoxic brain
- focal neurological signs
- coma
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how do you make the diagnosis of malaria?
- thick blood film: detects if pt HAS malaria
- thin blood film: detect WHICH type of malaria - allow SPECIATION & DENSITY - parasitaemia
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when interpreting a blood film, what 3 things do you check for?
- 1. infecting species eg mixed infection?
- 2. density of infection (%, high power field)
- 3. stage (trophozoites vs schizonts)
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if you see trophozoites on blood film what does that signify?
another 48 hours - not worried
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if you see schizonts on blood film, what does that mean?
- it is about to pop - very worried as don't want % density of infection to increase
- will produce high parastitaemia
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how do you confirm a pt does NOT have malaria?
- 3 sets of blood films
- from consecutive days
- to all be negative for malaria parasites
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when taking a hx of suspected malaria, what do you need to ask?
- travel hx - many years back
- p. malaria can present 1 year after return
- vivid and oval may have been acquired many years ago and relapse
- ask if took malarial prophylaxis - which drugs and how good was compliance
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which drug is falciparum resistant to?
chloroquine
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which malaria do sickle cell and thalassaemia have some protection against? how/why?
- falciparum malaria
- as protozoa are unable to reproduce as effectively in the RBC of sickle/thal hence limiting potential severity of disease
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what confers protection to p.vivax?
- blood group Duffy-negative
- as their RBC lack receptor required for the binding of merozoites to RBCs
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what is cerebral malaria?
- unarousable coma in the absence of any other cause than malaria
- happens with p.falciparum
- get fits, UMNL
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name all the Ix needed in suspected malaria?
- thick and thin blood films
- FBC: anaemia, thrombocytopenia
- U&E: renal impairment
- lactic acidosis with falciparum
- intravascular haemolysis: high bill, high LDH
- low glucose: complicates falciparum but may be SE of quinine
- urine dip: blood as Hburia with falciparum
- ECG: do before give quinine as can induce arrhythmia
- LP: in case think cerebral malaria, to rule out bacterial meningitis
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why do you do an ECG in malaria?
- before give quinine
- as can induce arrthtymia
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from blood tests, what are signs of intravascular haemolysis?
- raided bilirubin
- raised LDH
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if you see haemoglubinuria, which plasmodium suspect?
falciparum
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why do u do LP in malaria?
- if suspected cerebral malaria
- need to rule out bacterial meningitis
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which part of the world has the >90% of infections?
sub saharan africa
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what happens to a person who leaves an endemic area of malaria?
they lose their immunity very quickly
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what is sequestration in terms of malaria? why do you get it?
- when schizonts stick to the lining of small blood vessels
- happens because schizonts are large cells, they make RBC less squishy and have knobs on their surface which develop electrical charge
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what are consequences of sequestration?
- brain: cerebral malaria
- kidney: renal failure
- lungs: ARDS = main cause of death in malaria
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what is the mortality with cerebral malaria?
20%
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what is the standard treatment of falciparum malaria? and dose?
quinine 10mg/kg 8-12 hourly until asexual parasitaemia clears
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when is falciparum considered severe, what parasitemia?
>2%
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when do you give Rx iv?
- clinically unwelll
- parasitaemia >2%
- schizonts seen in peripheral blood (as likely to get much sicker, quickly)
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what are the 2nd agent drugs for malaria?
- artemisinin derivates
- doxycycline
- malarone = atovaquone + proguanil
- mefloquine
- fansidar = sulfadoxine-pyrimethamine
- best practice to use >1 anti-malarial
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which parts of the world do you get p.vivax?
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which parts of the world do you get ovale?
west and central africa
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why are vivax and ovale considered benign?
as parasitemia never >2%
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which malarias are relapsing?
vivax and ovale
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what is specific about p.malariae?
- never causes severe disease and
- may persist for decades
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what is a renal complication of p.malariae?
rare cause of nephrotic syndrome
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what is the treatment of benign malaria?
chloroquine and primaquine (hypnozoites)
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what do you have to do before starting primaquine and why?
- check G6P levels
- if G6PD (deficiency) then beware as primaquine causes haemolysis with G6PD
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what is treatment of p.malariae?
chloroquine alone
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give 3 different regimens for malaria prophylaxsi
- mefloquine 250mg weekly
- or
- doxycycline 100mg daily
- or
- malarone = atovaquone + proguanil 1 daily
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what are the complications of plasmodium falciparum?
- cerebral malaria inc seizures
- cardiovascular: septic shock, pulmonary oedema
- respiratory: ARDS
- renal: ARF, blackwater fever - Hburia
- DIC, anaemia, low plt
- hypoglycaemia, LA
- hyperpyrexia
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what are complications of p.malariae?
- nephrotic syndrome
- due to chronic GN which can be fatal in young children
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what do gametocytes look like on blood film?
banana
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what do schizonts look like on blood film?
lots of dots in a RBC
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