Malaria Flashcards
Describe the lifecyle of malaria
Malaria is spread by female Anopheles mosquitoes, usually at night. A feeding mosquito sucks up infected blood.
When that mosquito bites someone, the sporozoites are injected. These sporozoites travel to the liver of the newly infected person.
The malaria parasites mature in the liver into merozoites, which enter the blood and infect red blood cells.
In red blood cells, the merozoites reproduce, after which the red blood cells rupture, releasing loads more merozoites into the blood and causing haemolytic anaemia.
Which is the most common form of Plasmodium that causes malaria in humans? [1]
Which forms of Plasmodium cause malaria that can relapse in humans after months or years [1] or 2-3 years [1]
Plasmodium falciparum: Most common
Plasmodium vivax: has a dormant liver stage, relapses months - years later (< 2-3 yrs). Merozoites lie dormant as hypnozoites
Plasmodium ovale: dormant liver stage, which means disease can relapse with 2-3 years of onset. Merozoites lie dormant as hypnozoites
How often does rupture and release of merozoites occur in P.vivax and P. ovale? [1]
What symptom does this cause? [1]
What is the name for this? [1]
P. vivax and P. ovale:
- rupture and release of merozoites occurs every 48 hours
- causing a fever spike every other day.
- A fever every 48 hours is referred to as tertian malaria P. falciparum has more frequent (“subtertian“) or irregular fever spikes, and P. malariae has spikes every 72 hours (“quartan“).
How often does rupture and release of merozoites occur in P. falciparum? [1]
What symptom does this cause? [1]
What is the name for this? [1]
P. falciparum:
- rupture and release of merozoites occurs < 48hrs
- subtertian: irregular fever spikes
Describe the typical presentation of malaria [7]
- Fever (up to 41ºC) with sweats and rigors
- Fatigue
- Confusion
- Myalgia (muscle aches and pain)
- Headache
- Nausea
- Vomiting
State 3 signs of malaria [3]
Pallor (anaemia)
Splenomegaly
Jaundice (due to haemolysis)
TOM TIP: The most characteristic symptom of malaria is the fever, which spikes very high every 48 hours. In someone with an unexplained fever, consider whether they have travelled somewhere with malaria present. Even exposure several years ago may be relevant, as P. vivax and P. ovale can lie dormant for up to 4 years.
How do you diagnose malaria? [2]
malaria blood film:
- A malaria blood film will show the parasites, the concentration (as a percentage) and the type.
Three negative samples taken over three consecutive days are required to exclude malaria due to the parasites being released from red blood cells into the blood every 48-72 hours.
The sample may be negative when the parasites are not released but positive a day or two later when the red blood cells rupture and release the parasites.
What is the protocol with admissions and Falciparum malaria? [1]
The local infectious diseases team will advise on management. All patients with falciparum malaria are admitted.
What determines the treatment of malaria? [2]
The treatment of malaria depends on the species and whether it is uncomplicated or severe.
What determines if malaria is uncomplicated or complicated? [3]
Criteria for uncomplicated malaria includes:
* Parasitaemia < 2%
* No schizonts on film
* No clinical complications
Describe the management plan of uncomplicated P. falciparum malaria [2]
First-line options:
* Riamet (Artemether + lumefantrine): four tablets orally at 0, 8, 24, 36, 48 and 60 hours,
OR
* Malarone (atorvaquone + progunail): 4 tablets daily for 3 days
Second-line options:
* Quinine sulphate (600 mg TDS) + Doxycycline (200 mg OD): 7 days, OR
* Quinine sulphate (600 mg TDS) + Clindamycin (450 mg TDS): 7 days
Describe the management plan of complicated P. falciparum malaria [3]
First-line options:
* Artesunate: 2.4 mg/kg intravenous at 0, 12, 24 hours then once daily. Always follow local guidelines on prescribing.
* If unavailable, may require quinine initially until artesunate is acquired.
Second-line options:
* Quinine dihydrochloride: Requires dose adjustment in renal and hepatic impairment and cardiac monitoring duration administration. Follow local guidelines.
Follow-on therapy (once improved and able to tolerate oral tablets):
* Riamet (Artemether + lumefantrine): four tablets orally at 0, 8, 24, 36, 48 and 60 hours, OR
* Doxcycline: 200 mg once daily for 7 days, OR
* Clindamycin: 450 mg three times a day for 7 days (preferred in pregnancy)
TOM TIP: Remember artesunate and quinine as treatment options for your exams, as these are the most likely to be relevant. Remember that Plasmodium falciparum is the most common and severe cause, and these patients should be admitted for artesunate treatment and monitoring for complications.
What is a common side effect of artesunate treatment? [1]
haemolysis is a common side effect
