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Malaria

Malaria is a serious and sometimes fatal disease caused by a type of parasite called Plasmodium which are spread in the saliva of infected female Anopheles mosquitoes. Malaria is widespread in many tropical and subtropical countries, being present in more than 100 countries, including large areas of: Africa, Asia, Central and South America, parts of the Middle and Far East and some Pacific Ocean Islands.

There are 4 types of malaria that commonly affect humans: Plasmodium falciparum which is responsible for the vast majority of malaria deaths, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae. There is a 5th type, Plasmodium knowlesi, which is a parasite that usually infects monkeys, although it is emerging in South East Asia as a threat to humans, and in 2006 the first case was reported in the UK[60, 61, 62].


How is it contracted?
People acquire malaria after being bitten by an infected mosquito which usually feeds at night, between dusk and dawn. When an infected mosquito bites, the parasite enters the bloodstream as the mosquito takes a blood feed. The incubation period varies depending on the Plasmodium species causing the infection. During this incubation period, the parasite undergoes an initial period of development in the liver, after which it infects red blood cells. The incubation period for P. falciparum, is 7 to 14 days, while for P. vivax and P. ovale infection it is typically 12 to 18 days, but this can sometimes be for as long as several years [60].

Who is at risk?
The risk is particularly high in sub-Saharan Africa, in rural areas and at times of high seasonal rainfall. The majority of cases occur in children and 14% of children aged 2-10 years in sub-Saharan Africa had malaria in 2013 [63]. Pregnant women and the elderly are also at increased risk. There currently is no vaccination against malaria, though several are being developed, but partial resistance can develop in those who have recently survived an infection, although this dissipates over months to years with no ongoing exposure to malaria. Re-infection typically causes milder symptoms.

Signs and symptoms
Symptoms usually begin 10-15 days after being bitten and typically include shivering, fever, joint pain, vomiting, jaundice and convulsions. The classic symptom of malaria is a sudden feeling of coldness followed by fever and sweating. In severe cases, malaria can progress extremely rapidly and induce a coma and even death within hours or days. Complications from the disease are almost more frequently associated with P. falciparum infection, and can include: impaired consciousness or seizures, fluid in the lungs or acute respiratory distress syndrome, renal damage, rupture of the spleen, multiple organ failure and ultimately death. 

Outcome
When properly treated, people with malaria can usually expect a complete recovery although it can take a long time to get back to normality. Severe malaria can progress extremely rapidly and cause death within hours or days, with fatality rates reaching 20%, even with intensive care treatment. 

Treatment
There is a risk of rapid death, so people with suspected malaria are usually admitted to hospital although some patients are treated on an outpatient basis.  The recommended treatment for malaria is a combination of antimalarial medications that includes an artemisinin. Uncomplicated malaria may be treated with oral medications whilst intravenous administration is the recommended treatment for severe malaria.

Recommendations for Travellers
There is a significant risk of getting malaria to anyone travelling to an affected area. It is very important you take precautions to prevent it. Avoiding malaria involves several steps, known as the ‘ABCD’ of malaria prevention:

— Awareness of risk: know your risk of malaria before travelling.
— Bite prevention: avoid bites as much as possible.
— Chemoprophylaxis: take the right antimalarial tablets and complete the course to avoid reactivation of the disease.
— Diagnosis: get immediate medical help for symptoms (usually high fever 38C or greater).

Recommended preventative medicines for malaria will vary depending on destination and other factors. Travellers must always, through discussion with their GP, or travel health specialist make sure they use a drug which they can tolerate and one which is appropriate for their destinations as resistance occurs and no drug is 100% effective.

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Malaria. Here’s the point...

Malaria chemoprophylaxis ('malaria tablets') do not give complete protection and with no vaccine available at present, mosquito bite avoidance is key to disease prevention. In the UK, approximately 1,500 travellers are diagnosed with malaria each year and there have been between 2-10 deaths from malaria each year since 2005 [66]