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A 25-year-old student who returned 7 days ago from a 3-week trekking holiday in a remote area of Sierra Leone presents to A&E with a fever.
1. What are your immediate concerns
Malaria is the most important cause of fever in a traveller returning from an endemic area; however, in this case the traveller has visited a rural area where Lassa and other viral haemorrhagic fevers occur, so this has to be considered. The patient should be isolated in the A&E department while blood films or samples for malaria are processed. It is important to tell the laboratory handling the films that the patient has been in a viral haemorrhagic fever area. If these films are negative, specialist advice from communicable disease experts (Health Protection Agency in the UK, Center for Disease Control in the USA) should be sought regarding how to proceed
2. In this case malaria films are positive. Should you do any other investigations?
Multiple infections are possible, so a full sepsis workup should still be carried out. This should include blood cultures, urine analysis and stool culture, swabs of any wounds, and sputum culture if present. A full blood count, C-reactive protein and chest X-ray should be performed.
3. What are the key steps in the pathogenesis of malaria?
Infections are contracted when a female Anopheles mosquito injects sporozoa into the blood stream. These infect hepatocytes and are released to infect red blood cells (RBCs) causing subsequent release of cytokines and the development of fever. RBCs develop projections and adhere to capillary walls causing endothelial damage. Gametocytes are taken up by another mosquito and develop into sporozoites in the mosquito before being injected into another host.
4. How could this infection be prevented?
There are two arms to the prevention of malaria. Firstly antimalarial prophylaxis, which must be tailored to take into account the sensitivities of the malaria parasites in different geographic areas, and secondly efforts to prevent mosquito bites – insect repellent lotion, covering of arms and legs at night and sleeping under insect-repellent impregnated mosquito nets..
5. What complications can develop?
Severe malaria can be complicated by cerebral malaria, circulatory shock, acute haemolysis and renal failure, hepatitis and pulmonary oedema. Plasmodium falciparum is the species associated with severe complications because of its ability to produce a heavy parasitaemia.