What is malaria?

Malaria is a serious disease caused by a parasitic infection of the red blood cells, and can sometimes be fatal. Malaria is contracted through the bite of the infected Anopheles mosquito. Symptoms include fever and flu-like illness, and relapses may occur. Malaria is a common problem in areas such as Asia, Africa, and Central and South America, and can also occur in parts of the Middle East, Europe and the South Pacific. See your doctor before travelling to malaria risk areas, for antimalarial medication. Also use general mosquito prevention measures such as suitable clothing and insect repellents.

Five types of malaria

There are five kinds of malarial parasite that can infect humans:

• Plasmodium falciparum (can be life-threatening)
• Plasmodium vivax
• Plasmodium ovale 
• Plasmodium malariae
• Plasmodium knowlesi.

Bite injects parasites into blood

It is well known that malaria is contracted by the bite of mosquitoes. When an infected Anopheles mosquito bites you, it injects the malaria parasites into your blood. These parasites then travel through the bloodstream to the liver where they multiply. During this time, when the parasites are in the liver, you will not yet begin to feel ill.

The parasites then leave the liver and enter the red blood cells where the parasites grow and then burst the red blood cells, allowing them to move to another blood cell. At this stage, the parasites release toxins into the bloodstream and you will begin to feel ill.

How common is malaria?

According to the World Health Organization (WHO), malaria is a risk in tropical and subtropical areas of over 100 countries, and an estimated 30,000 international travellers become ill with malaria each year. The WHO's World Malaria Report 2010 estimates there were 225 million cases of malaria worldwide in 2009, of which there were 781,000 deaths, mostly in African children.

Malaria is a common problem in areas of Asia, Africa and Central and South America, but can also be found in parts of the Middle East, Europe and the South Pacific. Unless precautions are taken, anyone living in or travelling to a country where malaria is present can contract the disease.

See www.safetravel.govt.nz for updates on malaria and other disease alerts before travelling.

What are the symptoms of malaria?

The symptoms of malaria consist of fever and flu-like illness, including shaking, chills, headache, muscle aches, tiredness and a general feeling of illness. Because the symptoms are so general, malaria is often misdiagnosed. Nausea, vomiting and diarrhoea may also be present.

Malaria can also cause anaemia and jaundice (yellowing of the eyes and skin) because of the damage to the red blood cells.

If not promptly treated, the most serious form of malaria (Plasmodium falciparum) may cause kidney failure, seizures, mental confusion, coma and death.

How quickly do symptoms appear?

For most people, the symptoms of malaria will begin seven days to four weeks after the mosquito bite. However, the incubation period may be longer if you have taken an inadequate course of malaria prevention medications.

Two kinds of malaria (Plasmodium vivax and Plasmodium ovale) can cause relapses and some parasites may remain dormant in the liver for up to two years after you have been bitten by a mosquito.

How is malaria diagnosed?

Malaria is diagnosed by checking the blood for the malarial parasites. If you become ill with a fever or flu-like illness while travelling in high-risk areas and up to one year after returning home, you should immediately seek medical attention. You need to tell your doctor that you have been travelling in countries where malaria is a risk.

While a single positive blood test result is proof you have malaria, a single negative test is insufficient to exclude it. If you or your doctor strongly suspect you have malaria, at least three negative blood tests are required to prove you don't have it.

How is malaria treated?

Malaria is treated with certain types of prescription drugs. However, the type and length of treatment depends on which kind of malaria is diagnosed, where you were infected, how old you are, and how ill you were at the start of the treatment.

Prevention

Before leaving for an area where malaria is a risk, visit your doctor to find out about antimalarial medication. Normally, antimalarial medications are taken at least one week before you travel and continued for two to four weeks after you return. Also practice mosquito prevention measures to avoid getting bitten.

• The most active time for the mosquitoes that transmit malaria is from dusk till dawn and you should try to avoid going outside during this time, if possible.
• Wear long-sleeved shirts and long pants in light colours when going outside after dusk.
• Use mosquito repellents containing DEET (N,N-diethyl m-toluamide). However, do not apply these repellents on the hands of children who may wipe their hands on their eyes or put their hands in their mouths.
• Aim to stay in an air-conditioned or screened room, but otherwise sleep under a mosquito bed net that has been treated with permethrin insecticide.
• Use insect sprays containing pyrethrum in your living and sleeping areas. Lighting a ‘mosquito coil’ may also be effective.

It is still possible to get malaria even after using all the prevention measures, so if you experience any of the symptoms of malaria seek medical attention as soon as possible.

Related topics

See also Malaria - precautions when pregnant or breastfeeding and Travel vaccinations

Original content from myDr. Edited by everybody, November 2011.