MALARIA Flashcards
What are the four species that cause malaria?
Plasmodium falciparum
Plasmodium ovale
Plasmodium vivax
Plasmodium malariae
What is the name of the vector that is responsible for transmitting malaria?
The female Anopheles mosquito
What do we call the stage of the plasmodium life cycle where human are infected via the bite of the mosquito?
Sporozoites
Where do the sporozoites of plasmodium travel to when a human is bitten by the mosquito?
The liver
What stage of the plasmodium life cycle occurs in the human liver?
Asexual reproduction
What do we call the stage of the plasmodium life cycle which gets released into the blood from the liver in malaria?
Merozoites
At what stage of the life cycle of plasmodium does the patient start feeling fever?
When the merozoites are released into the blood stream from the hepatocytes
What happens to the merozoites of plasmodium in the blood stream during a malaria infection?
They infect red blood cells to further reproduce asexually. Each release of new merozoites causes a spike in fever, which gives malaria the characteristic cyclical spikes in fever.
Which species of plasmodium parasite can lay dormant in the liver leading to relapse of malaria?
P. vivax
P. ovale
Which species of plasmodium parasite can lay dormant in the blood stream leading to relapse of malaria?
P. malariae
What is the incubation period for P. falciparum parasite?
7-14 days
What is the incubation period for P. ovale parasite?
10-18 days
What is the incubation period for P. vivax parasite?
10-17 days
What is the incubation period for P. malariae parasite?
18-42 days
What is the time between each fever cycle (typical of malaria) of P. falciparum?
36-48 hours
What is the time between each fever cycle (typical of malaria) of P. ovale?
36-48 hours
What is the time between each fever cycle (typical of malaria) of P. vivax?
36-48 hours
What is the time between each fever cycle (typical of malaria) of P. malariae?
72 hours
Which red blood cells does P. falciparum tend to infect?
All of them especially the younger ones
Which red blood cells does P. ovale tend to infect?
Reticulocytes
Which red blood cells does P. vivax tend to infect?
Reticulocytes
Which red blood cells does P. malariae tend to infect?
Older cells
What is the mortality rate for someone infected with P. falciparum?
20%
What are P. ovale, P. vivax and P. malariae collectively called?
Benign malarias
How might someone with malaria present?
Travel history Periodic chills Rigors Periodic high fevers Drenching sweats Vomiting
Prodrome: Headache Malaise Myalgia Anorexia
What species of malaria is now considered resistant to chloroquine in many parts of the world?
P. falciparum
Can people from endemic areas build immunity to malaria?
Yes
Does the immunity to malaria built up in those from endemic areas last forever?
No, if they live somewhere else for a few years they will lose their immunity, but may travel without knowing this.
What might you notice on examination of someone with malaria?
Fevers up to 41 degrees Conjunctival pallor - anaemia Jaundice - haemolysis Hepatomegaly Splenomegaly
Which species of plasmodium is most likely to cause splenomegaly? Why?
P. malariae - chronicity of disease
Which species of plasmodium causes cerebral malaria?
P. falciparum
What are the features of cerebral malaria?
Unrousable coma
Rapid decline from reduced consciousness to coma and then death
Many suffer fits
On examination may elicit upper motor neuron pattern and nystagmus.
What investigations should be ordered for someone with suspected malaria?
Blood film FBC U&E's Lactate dehydrogenase Bilirubin Glucose levels Urine dipstick ECG LP
What might the blood tests of someone with malaria show?
Anaemia Thrombocytopenia Renal impairment Raised bilirubin - haemolysis Raised lactate dehydrogenase - haemolysis
What might be seen on a blood film of someone with malaria?
Schizont - cell with replicating parasites
Parasites themselves
From a blood film, how might you determine the severity of malaria?
Presence of a schizont indicates severe malaria
Parasitaemia of more than 2% indicates severe malaria
How many blood films would you need to take from a patient to confirm that a patient does not have or no longer has malaria?
Three films on consecutive days
Why is it important to check glucose level in a malaria patient?
Hypoglycaemia will complicate P. falciparum
Hypoglycaemia is a possible side effect of quinine
What might the urine dipstick of someone with malaria reveal?
Haemoglobinuria
Why is an ECG important in someone with malaria?
Quinine can induce arrythmias and conduction defects
Why would you perform an LP in someone with suspected cerebral malaria?
To rule out bacterial meningitis
What is the gold standard treatment for malaria caused by P. falciparum or by unknown cause?
Artemisinin combination therapy (ACT):
Artemether-lumefantrine
Artesunate-amodiaquine
Dihydroartemisinin-napthoquine
Atovaquone-proguanil (Malarone)
These are now accepted to be better than quinine, doxycycline or clindamycin
What drug can be used to treat malaria known to be caused by non-falciparum malaria?
Chloroquine + Primaquine
Always use different drug to prophylaxis though
What prophylactic drugs can be given to travellers to protect them against malaria?
Chloroquine - not useful in a lot of areas of resistance Quinine Doxycycline Mefloquine Malarone
What are the side effects of mefloquine?
Neuropsychiatric side effects
Other than anti-malarial agents, what other treatment do malaria patients need?
Supportive care - fluids
Paracetamol for fever
Blood transfusions - platelets and red cell
ITU - especially if cerebral malaria
What are the complications of falciparum malaria?
Cerebral malaria Septic shock ARDS (adult respiratory distress syndrome) AKI DIC Severe anaemia and thrombocytopenia Hypoglycaemic Hyperpyrexia
What are the side effects of doxycycline?
Sun sensitivity
What are the side effects of chloroquine?
Headache
Psychosis
Retinopathy
What are the side effects of quinine?
Retinopathy Optic atrophy Lichnoid planus (skin reaction) Thrombocytopenia Tinnitus
What are the side effects of primaquine?
Haemolysis in those with G6PD deficiency.
Why do we give primaquine to patients with non-falciparum malaria (ovale and vivax, not malariae)?
Destroys the liver hypnozoites to prevent relapse
