Malaria Flashcards
What is the difference between a prokaryotic and eukaryotic cell
Prokaryotic cell organelles are not membrane bound, but eukaryotic cell organelles are
Prokaryotes are unicellular, eukaryotes can be uni or multicellular
Prokaryotic cells are at least 100 times smaller than eukaryotic cells
Prokaryotic cells have circular DNA, eukaryotic cells have linear DNA
Prokaryotic cells reproduce by binary fission (asexually) eukaryotic cells can reproduce by mitosis/ meiosis (asexually) or sexually
What is a protozoa?
Give an example
Single celled eukaryotic cell
Plasmodium (protozoa that causes malaria)
What is an obligate parasite?
A parasite that can not survive independently as they require a host to complete their life cycle
Symptoms of malaria
Periodic episodes of severe chills, high fevers and profuse sweating
Episodes last ~ 6h
In anyone with unexplained fever, ask about travel (even several years ago) to malaria endemic countries
GI upset: abdominal pain, nausea, vomiting, diarrhoea
Respiratory distress - causes pulmonary oedema
Seizures - in cerebral malaria
Myalgia/ Arthralgia
Headache
Fatigue
Anorexia
Sore throat
Cough, lower respiratory tract symptoms, and respiratory distress
How do we diagnose malaria
Peripheral blood smears
Rapid diagnostic tests
Which factors guide antibiotic choice in malaria?
Plasmodium species
Clinical status
Drug sensitivity
What is the most severe type of malaria caused by?
Plasmodium falciparum
Which mosquito spreads plasmodium to humans?
The female anopheles mosquito
What is the most common type of plasmodium ?
Plasmodium falciparum
Which 5 species of plasmodium infect humans?
‘Know false, opaque vexing malaria’
P. knowlesi
P. falciparum
P. ovale
P. vivax
P. malariae
Describe the life-cycle of malaria
- Anopheles mosquitos feed on plasmodium infected blood
- Plasmodium reproduce sexually in the gut of mosquitos to make malaria spores (sporozoites)
- Anopheles mosquito bites a human so sporozoites enter their blood
- Sporozoites travel to human liver where they can lie dormant for years as hypnozoites if they are p.vivax or p.ovale
- Sporozoites mature into merozoites in the liver
- Merozoite cells overload the hepatocytes causing them to rupture
- Merozoites infect RBCs
- Merozoites rupture RBCs causing (haemolytic anaemia) and get released into blood to infect more RBCs
Incubation period malaria
1-4 weeks after exposure, although can lie dormant for 4 years if p.vivax/ ovale
How to exclude malaria as a diagnosis?
3 negative blood films over 3 consecutive days sent in EDTA (purple bottle)
Malaria management
Admit everyone with p. falciparum, if pregnant, under 18 or over 65 (if not admitting must get immediate advice from an infectious disease consultant)
1st line uncomplicated malaria: Artemether with lumefantrine
1st line for complicated malaria (requiring HDU/ ITU admission): IV Artesunate
Be aware quinines and doxycycline also play a role
Be aware different drugs are used in pregnancy
Inform public health england
Tell patient to notify close contacts/ who they travelled with
Inform patient an acute episode of malaria will not protect them from future attacks - need to avid mosquito bites/ get prophylactic treatment advice
Relapses of malaria can occur - must report fever
Complications malaria
Trophozoites (ball that sporozoite forms) makes RBCs sticky causing capillary occlusion in brain (coma), kidneys (renal failure) lungs (pulmonary oedema)
Cerebral malaria
Seizures
Reduced consciousness
Acute kidney injury
Black water fever - dark urine due to Hb release in blood
Disseminated intravascular coagulopathy (DIC)
Severe haemolytic anaemia
Multi-organ failure and death
What advice should give to patients travelling to malaria endemic areas
No method is 100% effective alone
Use mosquito spray (e.g., 50% DEET spray)
Use mosquito nets and barriers in sleeping areas
Seek medical advice if symptoms develop
Take antimalarial medication as recommended
Which anti-malarial medication option for prophylaxis has the least side effects?
Which patient group can not take it?
How long is it taken for?
Proguanil with atovaquone (Malarone)
Note can not be given in pregnancy
It is taken from two days before, until seven days after travel to an endemic area.
What is the only effective drug for the eradication of hypnozoites (dormant parasites which persist in the liver after treatment of P. vivax and P. ovale)?
Primaquine
Why is screening required before primaquine treatment?
It can cause fatal haemolysis in cause G6PD deficient individuals, so anyone requiring primaquine for hypnozoites has to be screened first
Prophylaxis options malaria
- Daily malarone (proguanil with atovaquone)
- Daily doxycycline
- Weekly mefloquine / chloroquine
DDx malaria
Dengue
Acute viral hepatitis
Haemolytic anaemia
Signs Malaria
Signs:
Haemolytic anaemia - pallor and jaundice
Splenomegaly - infected RBC get phagocytosed, splenic rupture can occur
Hepatomegaly
Renal abnormalities
Confusion
Hypoglycaemia
