Malaria is an infectious disease, widespread in tropical countries. Young children, pregnant women, travellers and people living in poverty-stricken areas are most at risk of serious illness and death from malaria. Approximately 1 million people die every year from the disease. Most of these deaths occur among children living in Africa. In the UK alone, over 2000 people each year return from a malarial zone to find they have been infected.
What Parasite Causes Malaria?
Malaria is caused by the Plasmodium parasite. Five species of Plasmodium are known to infect humans, including Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium knowlesi.
Plasmodium vivax is the most common cause of malaria, but the Plasmodium falciparum parasite is the most serious, infecting large numbers of red blood cells and potentially causing severe anaemia. Plasmodium falciparum infection can kill you within a few hours of the first symptoms and requires urgent medical attention. The Plasmodium falciparum parasite is common in African countries south of the Sahara desert.
The Plasmodium parasite is transmitted to humans by the Anopheles mosquito. When a female Anopheles bites a human infected with malaria, she takes in malaria parasites along with her blood meal. Then, when she bites another human, she injects the parasites into his or her bloodstream and they travel in the blood to the liver. They remain in the liver for a while before re-entering the bloodstream and invading red blood cells. Once inside the red blood cells, the parasites multiply.
Forty-eight to 72 hours later, the invaded red blood cells rupture and the parasites invade yet more red blood cells. Signs and symptoms of malaria occur alongside the cyclical rupturing of the red blood cells.
Signs and Symptoms of Malaria
Signs and symptoms of malaria typically begin within 7 to 30 days (known as the “incubation period”) of being bitten by an infected mosquito. However, Plasmodium vivax and Plasmodium ovale can stay dormant in the liver for many months or years, in which case symptoms may begin much later.
Malaria has flu-like symptoms including recurring bouts of fever, sweating (caused by a drop in body temperature), shaking chills and tiredness. Other signs of infection include headaches, nausea, vomiting, diarrhoea, jaundice and muscle pain. Symptoms can range from mild to severe.
Malaria can usually be treated with the correct and prompt treatment, but in severe cases there may be complications, such as:
Anaemia caused by damage to red blood cells
Low blood pressure
Kidney or liver failure
Problems with blood clotting
Premature birth or a low birth-weight baby if the disease is contracted during pregnancy
A ruptured spleen and internal bleeding
Respiratory failure caused by fluid build-up in the lungs
Non-Falciparum and Falciparum Malaria Treatment
Suspected malaria infection should be treated as a case of emergency. With the correct diagnosis and prompt treatment, a full recovery is likely. A blood test confirms parasites are in the blood and determines which species of Plasmodium is being treated.
Malaria treatment can be given orally, by injection or intravenously. The type of treatment needed depends on the severity of infection, which species of Plasmodium is the cause and if the patient took antimalarial tablets (prophylaxis).
Due to variations in drug-resistance between different strains of malaria, the treatment given also depends on where the patient contracted the infection. For example, United States treatment guidelines state that Plasmodium falciparum infection can be treated with chloroquine, if it was acquired in one of the few parts of the world where the Plasmodium falciparum parasite is not yet resistant to chloroquine.
Non-falciparum malaria is usually treated by orally administered chloroquine. Plasmodium vivax and Plasmodium ovale have dormant liver stages that can become active again many months or years later, therefore infection with these parasites requires additional primaquine treatment to prevent relapses.
Falciparum malaria treatment includes medicines such as quinine tablets or atovaquone-proguanil. If infection is acute (most likely caused by Plasmodium falciparum), quinine treatment may initially be given intravenously before being administered orally.
Chloroquine and proguanil antimalarial tablets can be bought over the counter from a pharmacist without a prescription. Chloroquine and proguanil are often taken together.
Two 250mg chloroquine tablets should be taken each week (on the same day) spent in a malaria risk zone, whether staying or just passing through, and two tablets should be taken one week beforehand, (also on the same day). This regime must be continued for four weeks upon return. Children aged 1-4 should have half a chloroquine tablet, children aged 5-8 should have one tablet, and children aged 9-14 should take one and a half tablets.
Two 100mg proguanil tablets should be taken each day spent in a malarial zone, whether staying or just passing through, and two tablets should be taken each day one week beforehand. This regime should be continued for four weeks upon return. Children aged 1-4 should have half a proguanil tablet, children aged 5-8 should have one tablet, and children aged 9-14 should take one and a half tablets.
Unfortunately, Plasmodium parasites have built up resistance to chloroquine and proguanil in many countries. For example, the Plasmodium falciparum parasite has become increasingly resistant to chloroquine in many parts of Africa, such as Kenya, Gambia and Nigeria. There are other anti malaria tablets available on prescription that may be more appropriate depending on the country you are visiting.
Ask a pharmacist, travel clinic or doctor about the right malaria prevention measures to take. Obtain your antimalarials from a reliable source before travelling, as there is a danger of being sold fake tablets elsewhere. The best protection against infection is to avoid bites from infected mosquitoes. Sleep under an insecticide-treated net, use an effective insect repellent and cover your skin with clothing. Fly screens and air conditioning are other useful weapons against biting insects.
If you experience a high fever while staying in an area with a high risk of malaria, or up to one year after returning home, seek medical help immediately. Severely infected individuals, children and pregnant women with the disease must be monitored closely.