Malaria is a serious and potentially life-threatening infection caused by the Plasmodium parasite. It is transmitted through the bite of an infected female Anopheles mosquito, which is most active between sunset and sunrise. The risk of contracting the disease also depends on the season of travel, altitude, specific location, length of stay and type of travel. After a human is bitten, the parasite (Plasmodium) makes its way to the liver for the first phase of its development. It then leaves the liver and invades the red blood cells. Certain types of malaria remain dormant and can cause relapses years later.
The clinical presentation of malaria is based on the species of Plasmodium involved. Generally speaking, the symptoms are similar to those of the flu and include the following:
- high fever;
- chills, excessive sweating;
- nausea, vomiting, diarrhea;
- headache, dizziness;
- muscle and joint pain.
Symptoms can last several hours, alternating with symptom-free periods (cycle). If the initial infection is not treated and, depending on the parasite involved, the disease may recur. Symptoms usually appear within 1 to 2 weeks of the mosquito bite but, in some cases, may only occur several months later. If you have travelled to an area where malaria is present and if you experience fever or flu-like symptoms within the year following your return, see a doctor as soon as possible.
People travelling to areas where malaria is present can take preventive drugs. Given the possibility of drug-resistance, the drugs prescribed may vary based on the destination. Currently, there is no vaccine available against malaria.
Because no antimalarial drug is 100% effective, additional measures are recommended:
- avoid activities outside between sunset and sunrise;
- use an insect repellent that contains DEET or icaridin;
- avoid scented products;
- if sleeping in a screened and air-conditioned room is not an option, sleep under an insecticide-treated (permethrin) bednet;
- consider wearing insecticide-impregnated (permethrin) clothing;
- reduce length of stay in areas at risk and avoid travel during peak seasons;
- wear long, light-coloured clothing.
For more information:
Essential Information for Canadians Abroad