Malaria Flashcards
Give examples of malaria parasites.
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium knowlesii
Where is malaria most common?
In Sub-saharan africa and south east asia.
Most common malaria species in Sub-saharan africa.
Plasmodium falciparum
Most common malaria species outside of sub-saharan africa.
Plasmodium vivax
Explain the malaria lifecycle.
Depends on the human and the mosquito.
Sporozoites are transferred to a person via a mosquito. The sporozoites then travel to the liver via the blood and mature in the liver.
In the liver schizonts are formed containing 30000 merozoite offspring.
If the species is able to be dormant in the liver such as vivax and ovale the merozoites can be released from the liver weeks, months or years after initial infection leading to recurrent disease.
The rupture of schizonts releases merozoites which will then enter the RBCs. In the RBCs the merozoites form larger trophozoites and erthrocytic schizonts.
The rupture of a erthrocytic schizont produces the clinical manifestations of malaria.
Clinical presentation of malaria. (Mainly falciparum)
Presentation most commonly occur within 3 months of return from an endemic area.
Non-specific symptoms such as;
Abrupt onset of rigors
Fever
Headache
Malaise
Myalgia
Diarrhoea
N+V
Cough
Fever pattern
Explain fever pattern in malaria.
Only occur if rupture of infected RBCs is synchronised.
Alternate day for falciparum, vivax and ovale.
Every 3rd day for malariae.
However most patients have no specific fever pattern.
Examination findings of malaria.
Fever
Jaundice, confusion, hepatosplenomegaly and seizures if severe disease.
Diagnosis of malaria.
Immediate blood testing is mandatory in the UK.
- Microscopy of thick and thin blood film/smear.
- Rapid diagnostic test (RDT) to detect parasite antigen. This is used for initial screen if expert microscopy is unavailable such as out of hours. It is used in addition to, not instead of blood film.
If malaria is suspected but blood film is negative then repeat at 12-24h and after further 24h.
Malaria is unlikely if three expert serial blood films are negative.
Differentials of malaria.
Dengue
Typhoid
Hepatitis
Meningitis/Encephalitis
HIV
VHF
Why do you need to be cautious of ruling out malaria in pregnant women?
Thick films can be negative despite parasites in the placenta.
What is additional information regarding RBCs should be given if the malaria is falciparum?
The estimated % of parasitised RBCs.
This is because the percentage is an estimation of the severity of disease and can give a prognosis of outcome and complications.
2% = chance of severe disease
10% = severe disease
Other investigations to be done in malaria.
FBC (anaemia and thrombocytopenia)
Crea
Urine output (AKI)
Clotting (DIC)
Glucose (hypo)
ABG/Lactate (acidosis)
Urinalysis (haemoglobinuria)
LFTs
Features of severe falciparum malaria.
Impaired consciousness/seizures
AKI
Shock
Hypoglycaemia
Pulmonary oedema/ARDS
Hb <80 g/L
Spontaneous bleeding or DIC
Acidosis
Haemoglobinuria
Parasitaemia > 10%