Malaria Flashcards
What are the five species of malaria which affect humans?
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Plasmodium knowlesi
What is the most severe species of malaria
Plasmodium falciparum
What is the vector for malaria?
Female Anopheles mosquito
Incubation period for malaria
6 days to 1 year
P. falciparum - up to 4 weeks
P. vivax/ovale - up to 1 year
What can the incubation time of plasmodium falciparum be?
Up to 4 weeks
What can the incubation time of plasmodium vivax/ovale be?
Up to 1 year
Presentation of malaria
- rigors
- paroxysmal fever
- malaise
- headache
- myalgia
- abdominal pain
- N+V
- jaundice + hepatosplenomegaly in later stage
What is paroxysm fever?
Fever that occurs in short bursts
Investigation needed for suspected malaria
Blood film x3 - thick + thin
Blood tests -FBC, U&E, LFT
Chest X ray
Head CT - neurological symptoms
Investigation findings of malaria
- seen on blood film
- anaemia
- thrombocytopenia
- leukopenia
- abnormal LFTs
- high urea, bilirubin + CRP
What is the characteristic image in malaria blood film?
Headphone/wedding ring
What investigation findings exclude malaria?
three negative blood film samples taken over 3 consecutive days
How do you grade the severity of malaria?
Parasitaemia
>5% indicates severe malaria
Calculated by the thin blood film
Complicated vs uncomplicated malaria
- uncomplicated is less severe symptoms i.e no signs of organ dysfunction or life threatening complications | often caused by P.vivax/ovale/malariae
- complicated is life threatening + involves organ dysfunction + high parastic load | most commonly caused by P.falciparum
Treatment of uncomplicated malaria
- first line: artemether + lumefantrine
- quinine + doxycycline
- malarone (proguanil + atovaquone)
- chloroquine (not P.falciparum)
- primaquine
Treatment of complicated malaria
- first line: IV artesunate
- quinine dihydrochloride
What drug should be used to treat liver related dormant malaria?
primaquine
What drug shouldn’t be used for P. falciparum malaria?
Why?
Chloroquine
Widespread resistance
Who should you not give primaquine to and why?
G6PD patients
can cause severe haemolysis
Describe the life cycle of plasmodium falciparum
1- female Anopheles mosquito bites human
2- injects sporozoites
3- sporozoites infect hepatocytes
4- sporozoites mature to merozoites
5- merozoites burst out of cell + infect bloodstream
6- merozoites attach erythrocytes
7- plasmodium asexually replicate + mature in RBCs
8- merozoites burst out of erthyrocytes (schizont)
9- process repeats
What is schizont?
The name of a erythrocyte when merozoites are ready to burst out of them
Name of erythrocytes when merozoites are ready to burst out of them
Schizont
How does malaria cause symptoms of haemolytic anaemia?
What is the exception?
Destruction of erthyrocytes
Plasmodium falciparum doesn’t
What is icterus
Yellow eye - jaundice
Prevention of malaria
Insecticide spray
Clothing that covers whole body
Mosquito nets
Avoid still lakes
Chemoprophylaxis
Examples of antimalarial medications
- malarone (proguanil with atovaquone)
- doxycycline
- mefloquine
Side effects of doxycycline
- diarrhoea
- thrush
- headache
- angioedema
- skin sensitivity to sunlight (increases sunburn risk)
Side effects of mefloquine
- psychiatric side effects
- anxiety
- depression
- diarrhoea
- dizziness
- sleep disorders
- psychosis or seizures (rare)
Why should you avoid still lakes to prevent malaria?
Anopheles mosquitoes lay eyes in stagnant water
What are the categories for recurrent malaria?
- Recrudescence - original parasite not killed
- Relapse - cleared merozoites, dormant hypnozoites in liver are no longer dormant
- Reinfection - original cure, new case of infection
Why does malaria caused by plasmodium falciparum not cause haemolytic anaemia?
1- P. falciparum cerastes sticky protein
2- protein coats surface of RBCs
3- RBCs clump together + occlude blood vessels
4- organ ischaemia
where do plasmodium species remain dormant within the human body?
Liver
ABCs of malaria prevention
Assess risk
Bite prevention
Chemoprophylaxis
What group of people have immunity to malaria?
Those with Sickle cell anaemia
Complications of plasmodium falciparum malaria
- cerebral malaria > seizures + neurological deterioration > death
- AKI
- pulmonary oedema
- DIC
- hypoglycaemia