What is malaria?

Malaria is an infection of the blood that is carried from person to person by mosquitoes. The disease has been recognized for thousands of years and once was found almost everywhere except in the most northern areas of the world.  However, it remains a serious problem in much of the tropical and subtropical world.

Millions of people continue to be infected every year and close to one million of them die.

Malaria symptoms

With malaria you develop a high fever, which comes and goes every other day or few days. How often a fever returns varies with each species of malaria.

• Many infections do not show this classic pattern of returning fevers at all. In many people the infection will seem more like flu with high fever and body aches.
• People also will complain of headache, nausea, shaking chills (rigors),sweating and weakness.
• As the infection progresses the fevers get less severe and you seem to recover. However, the infection can remain in many people for several years, particularly for those with a long history of exposure to malaria.
• These people can develop some immunity and may be infected for many years while only rarely having symptoms.

The different types of malaria each bring on their own complications.

• P falciparum: You can develop severe haemolytic anaemia (the red blood cells actually break down), kidney failure, coma and death. Treatment is a medical emergency. Drug resistance has become widespread. Current information on disease patterns, prevention for travellers and drug resistance can always be found through a travel health clinic or your GP surgery.
• P ovale: This species also can cause anaemia, but this infection is rarely life threatening.
• P vivax: You can develop anaemia and rupture of the spleen, which can become life threatening. People with P vivax or P ovale may relapse several months after the initial illness because of the persistence of dormant forms (called hypnozoites) remaining in the liver. These should be eradicated with medical treatment.
• P malariae: This infection is rarely life threatening, but a long-standing disease can lead to kidney failure. If untreated, this infection can last throughout your life.

Malaria causes

Malaria is caused by protozoan of the genus Plasmodium.

• Infection begins with a bite from an infected mosquito.
• The parasite travels from the mosquito to your liver, where the parasite begins to reproduce.
• The parasite leaves the liver and travels to the bloodstream, where it infects red blood cells. The parasite reproduces in the red blood cells, which destroys the cells and releases more parasites into the bloodstream.
• If another mosquito bites an infected person, that mosquito can then carry the infection to someone else.

There are four species of Plasmodium that infect humans:

• P vivax – Most common in India and Central and South America but found worldwide. It has an incubation period of 8-13 days. Infections can sometimes lead to life-threatening rupture of the spleen. In people treated only with chloroquine, this type of malaria can hide in the liver and return later.
• P ovale – Rarely found outside Africa. This form of malaria has an incubation period of 8-17 days and can hide in the liver of partially treated people and return later.
• P malariae – Found worldwide but less common than the other forms. This form of malaria has an incubation of 2-4 weeks. If untreated, the infection can last many years.
• P falciparum – Common worldwide, this is the most life-threatening form of malaria. This parasite has an incubation period of 5-12 days. Resistance to many of the medicines used to treat or prevent malaria is increasing.
• Although most people acquire malaria through mosquito bites, in some foreign countries the disease can have other sources.
  • Every year a handful of people are infected through blood transfusions or organ transplants.
  • IV drug users can develop malaria from sharing needles.
  • Each year a few babies are born to mothers who did not know they were infected. The babies then develop malaria.

When to seek medical care

People who recently have traveled to a country in which malaria exists and who develop a high fever or other symptoms that may be malaria should seek immediate medical attention at the GP’s surgery or at a hospital.

Examinations and tests

A healthcare professional will perform blood tests to determine if you have malaria and, if so, which type.

Malaria treatment

• Your doctor will prescribe a medicine or a combination of medicines straight away, depending on the type of strain and where you were infected.
• In much of the world, malaria is treated at home with oral medication and fluids. Severe infections require IV drug therapy.
• The most important aspect of home care is to make sure you drink lots of fluids and not to become dehydrated.

Next steps follow-up

• People infected with P vivax or P ovale will need to take chloroquine for several weeks after being treated in order to kill the parasites hiding in the liver.
• Report any recurrent fever or symptoms to your doctor because treatment failures are fairly common, and additional treatment will be indicated.
• Do not donate blood for several years after having been exposed to malaria.

Prevention

• For people travelling to areas where malaria exists, prevention is perhaps the most important aspect of managing the disease. Seek advice well before you travel, because some medications need to be started before you travel. DEET, or diethyltoluamide, is one of the most commonly used repellents that the NHS says is effective in sprays, roll-ons, sticks and creams. However, London School of Hygiene and Tropical Medicine researchers have found mosquitoes are able to ignore the smell of one of the most popular insect repellent ingredients a few hours after first being exposed to it, highlighting the importance of taking additional precautions such as the use of mosquito nets.
• Several medications are used to prevent infections during foreign travel. The pattern of resistance to these medications is constantly changing.
• In some parts of the world, P falciparum is resistant to all these medications.