Malaria Flashcards
what is the definition of malaria?
Protozoan infection caused by Plasmodia spp.
what is the epidemiology of malaria?
300-500 million cases per year (80% Africa)
700,000 - 2.7 million deaths a year (more than 90% African)
Cause of 50% of fever in African children under 5
50% of world population at risk
Increasing incidence
what is the aetiology of malaria?
4 species cause human disease: • P. falciparum (most common) • P. ovale • P. vivax • P. malariae - Transmitted by the bite of the FEMALE ANOPHELES MOSQUITO
what are the risk factors for malaria?
travel to endemic area
inadequate or absent chemoprophylaxis
insecticide-treated bed net not used in endemic area
settled migrants returning from travel to endemic area
what is the pathophysiology of malaria?
Pathology is related to anaemia, cytokine release and in the case of P.falciparum - widespread organ damage due to impaired microcirculation
• The anaemia is due to:
- Haemolysis of infected red cells
- Haemolysis of non-infected red cells (Blackwater fever - when malaria is left to go untreated results in dark coloured urine)
- Splenomegaly
- Folate depletion
• In P.falciparum malaria:
- Red cells contains schizonts adhere to the lining of capillaries in the brain, kidneys, gut, liver and other organs
- As well as causing mechanical obstruction, these schizonts can rupture, releasing toxins and stimulating further cytokine release
what are the key presentations of malaria?
presence of risk factors for acquiring malaria
presence of risk factors for severe disease
fever or history of fever
what are the signs of malaria?
Recent travel to endemic area
what are the symptoms of malaria?
weakness Arthralgia - Chills & sweats - Headache - Myalgia - Fatigue - Nausea & vomiting - Diarrhoea
what are the first line investigations for malaria?
Giemsa-stained thick and thin blood smears:
Thick film:
• Sensitive but low resolution (difficult to interpret and speciate the parasite but have a higher yield)
• Tells you is malaria is present
- Thin film:
• Can identify morphological features and quantification of parasitaemia
• Tells you type and parasite count, above 2% = severe
• Identification of species on thin film - trophozoite most commonly used
- 3 separate films should be examined before malaria is declared unlikely
rapid diagnostic tests (RDTs)
FBC
clotting profile
what are the gold standard investigations for malaria?
polymerase chain reaction (PCR) blood for malaria
chest x-ray
blood culture
urine culture
what are the differential diagnoses for malaria?
Dengue fever
Zika virus infection
Chikungunya virus
how is malaria managed?
IV ARTESUNATE (gold standard) • or IV QUININE (second best since causes hypoglycaemia so monitor sugar levels • Uncomplicated falciparum malaria: - ORAL RIAMET - or ORAL QUININE - Add Doxycycline as 2nd agent to treat undiscovered/untreated malaria • Non-falciparum malaria: - ORAL CHLOROQUINE • P.vivax & P.ovale malaria: - PRIMAQUINE for hypnozoite clearance
how is malaria monitored?
Patients on treatment for severe malaria should have one set of blood smears (thick and thin smear) performed every 12–24 hours until a negative result (no Plasmodium parasites are detected) is reported
what are the complications of malaria?
cerebral malaria, pulmonary oedema, acute renal failure, severe anaemia, and/or bleeding
what is the prognosis of malaria?
If malaria is identified promptly, appropriate treatment is given, and no organ dysfunction has occurred, most people make a rapid and complete recovery. If malaria treatment is delayed or inappropriate, severe or fatal malaria can develop. Untreated severe malaria is fatal in the majority of cases.
