what type of organism is plasmodium?
what are the 4 species of plasmodium?
what does plasmodium need to do in order to complete their life cycle?
must pass through both hosts to complete the life cycle
what are the 2 types of reproduction done by the plasmodium and where?
- sexual in mosquito (gametogony)
- asexual in humans (schizogony)
why is it the FEMALE anopheles mosquito that causes malaria?
females need to such blood to get iron
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
what is plasmodium FALCIPARUM also known as and why?
- MALIGNANT: can be fatal, higher morbidity and mortality
- TERTIAN: as fever on day 1, 3…
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
which is the least common plasmodium? and how often fever? name>
- quartan ie fever on d1, d4
what are the 2 benign tertian malarias?
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
which plasmodiums have a fever cycle of 48 hours?
which plasmodium has a fever cycle of 72 hours?
which RBC does falciparum infect?
which RBC does ovale and vivid infect?
which RBC does malaria infect?
what is the dormancy site for falciparum?
what is the dormancy site for oval?
what is the dormancy site for vivid?
what is the dormancy site for malaria?
which plasmodium relapse after successful treatment?
- (NOT falciparum)
what is the mortality of each plasmodium?
- 20% for falciparum
- very low for the rest
what may pts with malaria notice in their urine?
dark due to haemolysis
what are the symptoms of malaria?
- fever (cyclical so may not have it when you see the pt)
- myalgia, arthralgia
- DARK URINE
what are the signs of malaria?
- jaundice - haemolysis
- pallor - anaemia as destroyed RBC
- splenomegaly - due to broken down RBC, can be massive with p.malariae as chronic infection
- altered consciousness - sticky RBC so anoxic brain
- focal neurological signs
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
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)
if you see trophozoites on blood film what does that signify?
another 48 hours - not worried
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
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
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
which drug is falciparum resistant to?
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
what confers protection to p.vivax?
- blood group Duffy-negative
- as their RBC lack receptor required for the binding of merozoites to RBCs
what is cerebral malaria?
- unarousable coma in the absence of any other cause than malaria
- happens with p.falciparum
- get fits, UMNL
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
why do you do an ECG in malaria?
- before give quinine
- as can induce arrthtymia
from blood tests, what are signs of intravascular haemolysis?
- raided bilirubin
- raised LDH
if you see haemoglubinuria, which plasmodium suspect?
why do u do LP in malaria?
- if suspected cerebral malaria
- need to rule out bacterial meningitis
which part of the world has the >90% of infections?
sub saharan africa
what happens to a person who leaves an endemic area of malaria?
they lose their immunity very quickly
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
what are consequences of sequestration?
- brain: cerebral malaria
- kidney: renal failure
- lungs: ARDS = main cause of death in malaria
what is the mortality with cerebral malaria?
what is the standard treatment of falciparum malaria? and dose?
quinine 10mg/kg 8-12 hourly until asexual parasitaemia clears
when is falciparum considered severe, what parasitemia?
when do you give Rx iv?
- clinically unwelll
- parasitaemia >2%
- schizonts seen in peripheral blood (as likely to get much sicker, quickly)
what are the 2nd agent drugs for malaria?
- artemisinin derivates
- malarone = atovaquone + proguanil
- fansidar = sulfadoxine-pyrimethamine
- best practice to use >1 anti-malarial
which parts of the world do you get p.vivax?
which parts of the world do you get ovale?
west and central africa
why are vivax and ovale considered benign?
as parasitemia never >2%
which malarias are relapsing?
vivax and ovale
what is specific about p.malariae?
- never causes severe disease and
- may persist for decades
what is a renal complication of p.malariae?
rare cause of nephrotic syndrome
what is the treatment of benign malaria?
chloroquine and primaquine (hypnozoites)
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
what is treatment of p.malariae?
give 3 different regimens for malaria prophylaxsi
- mefloquine 250mg weekly
- doxycycline 100mg daily
- malarone = atovaquone + proguanil 1 daily
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
what are complications of p.malariae?
- nephrotic syndrome
- due to chronic GN which can be fatal in young children
what do gametocytes look like on blood film?
what do schizonts look like on blood film?
lots of dots in a RBC