Malaria is a parasitic disease caused by one of four species of the protozoan Plasmodium - Plasmodium falciparum, P. vivax, P. ovale and P. malariae. It affects millions of people worldwide in tropical regions, and causes up to 3 million deaths annually. It is one of the three most lethal infectious diseases globally.

All malaria may cause:

• fever
• chills
• headache
• nausea
• sweating as fever subsides

These symptoms can cycle for a period of time.  

Untreated malaria can result in:

• enlargement of the spleen
• anemia
• decrease in the count of blood platelets

Severe malaria symptoms are more common with falciparum disease and may cause:

• severe anemia
• jaundice
• kidney  failure
• hypoglycemia
• respiratory distress
• coma (when the brain is affected)
• bleeding problems and shock

The incubation period is 9-18 days.

The infectious agents, P. falciparum, P. vivax, P. ovale and P. malariae are spread by the Anopheles species of mosquito. Human beings are the primary reservoir, but P. malariae can also be found in African apes and perhaps South American monkeys.  

Infection can also occur through blood transfusion, organ transplant, unsterilized  medical instruments and from mother to infant in the womb.  

Complications of falciparum malaria are mentioned above. The fatality rate for falciparum malaria, if caught early, is ~ 0.1 per cent. If treated in the later stages, this rises to 15 to 20 per cent. 

Malaria caused by P. vivax, P. ovale  and P. malariae is less frequently  life-threatening.  

Malaria is confirmed by one of the following:

• microscopic examination of blood smears
• testing for parasite antigens (rapid tests are available in some countries)
• using the PCR test (not always available)  

There are several treatments in use throughout the world for malaria.  Choice of drugs depends on the type of malaria and on the pattern of resistance in the part of the world where it was acquired.  Your physician will prescribe the appropriate medication in consultation with a specialist.    

If you are travelling to a malaria-risk area, there are things you need to do before you travel, while you are away, and when you return. 

Avoid being bitten by mosquitoes. The following measures can reduce your chance of infection by 90% or more: 

• If taking part in outdoor activities between dusk and dawn, use insect repellent on all exposed skin (one containing 30% concentration of DEET if possible, for longer lasting protection). Children should use no more than 20% DEET. Follow application instructions carefully. You may need to repeat application every 3-4 hours, especially in hot and humid climates. The repellent should be washed off once indoors as it may be absorbed through the skin.
• Wear light coloured clothing and long sleeves, trousers and socks.   (Clothing can also be treated with insect repellant prior to use.)
• Sleep in places with screened windows and doors, or places which have air conditioning (so you can close the windows and doors without being too hot and uncomfortable).
• Sleep under an intact, small-mesh mosquito net which has been sprayed with a permethrin or deltamethrin (insecticide) preparation. Tuck mosquito net under the mattress before nightfall. The mosquito net is particularly important if you cannot stop mosquitoes from entering your room.
• Use insecticidal spray indoors in the evening.
• Use non-perfumed cosmetics and toiletries. Mosquitoes are attracted to scented products.

Before you travel, seek advice from your local travel clinic or family doctor at least one month before your departure. They will advise you of the malaria risk in the area you're planning to visit. 

• If anti-malaria medications are recommended, you will get a prescription.
• Make sure you are aware of the possible side-effects of the prescribed anti-malaria medication, and that you know how to take the medication correctly.
• While you are away, take your anti-malaria medication for the entire time you are in the malaria-risk area and as long afterward as recommended on your prescription. 

Even when taking all of these measures, there is a small chance of developing the disease. If you develop a fever (up to 6 months after your return) or other symptoms such as persistent headaches or muscle aches, consult your doctor and tell him/her about your travels. Early diagnosis can prevent serious complications. 

The effects of malaria are more severe in children, pregnant women and their developing babies. Pregnant women and infants should not take certain anti-malaria medications. Therefore, pregnant women and infants should avoid travel to areas where these medications are required for malaria prevention (areas of chloroquine-resistant malaria). If travel is required, pregnant women and women with infants should visit a local health unit travel clinic or their family doctor to find out if there is a medication they can take safely for their trip. If travel is required, extra precautions are necessary to protect pregnant women and infants from mosquito bites.

Reference:
Control of Communicable Diseases Manual, Heymann, 2008