Malaria
	Know before you go!
	Disease profile
	Transmission
	Geographic distribution
	Symptoms
	Treatment
	Prevention & precautions
	- Avoiding    Mosquitoes
	- Antimalarial    medication
	- Children and    DEET
	Some things to think about
	Travel Health Advisories

Malaria

Updated: February 2005

Know before you go!

Infectious diseases not necessarily common in Canada can occur and may even be widespread in other countries. Standards of hygiene and medical care may differ from those at home. Before departure, you should learn about the health conditions in the country or countries you plan to visit, your own risk of disease and the steps you can take to prevent illness.

The risk is yours
Your risk of acquiring a disease depends on several factors. They include: your age, gender, immunization status and current state of health; your itinerary, duration and style of travel (e.g., first class, adventure) and anticipated travel activities (e.g., animal contact, exposure to fresh water, sexual contact); as well as the local disease situation.

Risk assessment consultation
Public Health Agency of Canada strongly recommends that your travel plans include contacting a travel medicine clinic or physician 6 to 8 weeks before departure. Based on your individual risk assessment, a health care professional can determine your need for immunizations and/or preventive medication (prophylaxis) and advise you on precautions to avoid disease. We can help you locate a travel medicine clinic closest to your home.

Some facts from the experts
The information below has been developed and is updated in consultation with The Public Health Agency of Canada Committee to Advise on Tropical Medicine and Travel (CATMAT). The recommendations are intended as general advice about the prevention of malaria for Canadians travelling internationally.

Malaria is an acute flu-like illness caused by one of four species of parasite of the genus Plasmodium, a parasite: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae. Infection with P. falciparum can be fatal. Infection with P. vivax and P. ovale is not fatal; however, these strains have the ability to remain dormant in the liver for many months and can delay symptoms of malaria from appearing for several months after the traveller has been exposed. Relapses of malaria infection can also occur with these strains.

The disease is most commonly transmitted to humans through a bite of an infected mosquito, specifically the female Anopheles mosquito, a dusk-to-dawn biter. While rare, the parasite can also be transmitted by transfusion with infected blood, or by shared needle use, or from a mother to her unborn child.

Malaria is endemic (i.e., constantly present) in most of sub-Saharan Africa; in large areas of the Middle East, South Asia, South East Asia, Oceania, Haiti, Central and South America; and in parts of Mexico, North Africa and the Dominican Republic. From time to time in endemic areas, the number of malaria cases can increase dramatically to the epidemic level.

Malaria is not foreign to Canada. The number of imported cases of malaria varies from year to year, and is generally around 400 cases annually with a high of 1,036 reported cases in 1997. However, it is estimated that only 30% to 50% of cases are reported to public health agencies. Therefore, the true number of imported cases into Canada is likely to be higher.

Ten percent of the Canadian population travels to international destinations (excluding the United States) annually, and many travel through malaria-endemic areas. Due to the anticipated increase in Canadians travelling and the changing geographic distribution of malaria worldwide, the rate of imported malaria in Canadians is likely to increase.

Malaria is endemic (i.e., constantly present) in most of sub-Saharan Africa; in large areas of the Middle East, South Asia, South East Asia, Oceania, Haiti, Central and South America; and in parts of Mexico, North Africa and the Dominican Republic. From time to time in endemic areas, the number of malaria cases can increase dramatically to the epidemic level.

Malaria is not foreign to Canada. The number of imported cases of malaria varies from year to year, and is generally around 400 cases annually with a high of 1,036 reported cases in 1997. However, it is estimated that only 30% to 50% of cases are reported to public health agencies. Therefore, the true number of imported cases into Canada is likely to be higher.

Ten percent of the Canadian population travels to international destinations (excluding the United States) annually, and many travel through malaria-endemic areas. Due to the anticipated increase in Canadians travelling and the changing geographic distribution of malaria worldwide, the rate of imported malaria in Canadians is likely to increase.

Symptoms of malaria include fever and flu-like symptoms such as headache, nausea, vomiting, muscle pain and malaise. Rigors (severe shakes or muscle spasms) and chills often occur. Acute infection can cause enlargement of the spleen and make the liver tender. Cerebral malaria, which may occur with P. falciparum infection, affects the brain, and its symptoms include personality change, confusion, lethargy and seizures.

The severity of the illness varies depending on which species of the malaria parasite is responsible for the infection. Of the four species causing malaria, P. falciparum leads to the most serious illness. Severe falciparum malaria can cause seizures, coma, kidney failure and respiratory failure, which can lead to death.

Because the symptoms of malaria are non-specific, an accurate diagnosis is not possible without a blood test.

Fever occurring in a traveller within three months of departure from a malaria-endemic area is a medical emergency and should be investigated urgently with thick and thin blood films. These tests should be repeated 12 to 24 hours later if symptoms persist.

A traveller must seek medical attention as soon as possible for unexplained fever that arises during or after travel to an area where malaria occurs. The traveller should request that a blood film (thick and thin films) be examined for malaria parasites. Progression from asymptomatic infection to severe and complicated malaria can be extremely rapid, with death occurring within 36 to 48 hours.

Treatment for malaria depends on several factors: the species of malaria causing infection, severity of infection, the age of the infected individual, and the pattern of drug resistance to malaria treatment in the area where the individual acquired the infection.

If identified early and treated appropriately, almost all malaria can be completely cured. However, even short delays in the diagnosis of malaria can make treatment more difficult and less successful.

There are two important measures to prevent malaria infection: avoiding mosquito bites and using antimalaria medication.

Recommendations

Personal measures to avoid mosquitoes
Any measure that reduces exposure to dusk-to-dawn biting mosquitoes during their feeding will also reduce the risk of acquiring malaria. These measures include:

Protective clothing

• Wear clothing that reduces the amount of exposed skin.
• Wear light-coloured, long-sleeved shirts, long pants, socks and shoes when outdoors between dusk and dawn (note: dark colours attract mosquitoes).
• Impregnate all clothing with 0.5% permethrin to make them repellant.
  

Screens and bed nets

• Sleep inside screened areas, under a mosquito net or in an air-conditioned room.
• Use bed nets that are rectangular in size, impregnated with permethrin every six months and tucked tightly under the mattress before dusk (note: treated bed nets are available in Canada).

Insect repellent

• apply DEET-containing insect repellent to exposed skin when outdoors between dusk and dawn.

Of the insect repellents registered in Canada, those containing 'N, N diethyl-m-toluamide' (DEET) are the most effective. Although the concentration of DEET varies from product to product, repellency rates are largely equivalent. In general, higher concentrations protect for longer periods of time, but there is little advantage in the duration of repellence with DEET concentrations greater than 50%, and there may be additional risk of toxicity with higher concentrations. New micro-encapsulated products containing 33% DEET are registered in Canada, and they should provide up to eight hours of protection.

Antimalarial medication (prophylaxis)
The Public Health Agency of Canada strongly recommends travellers obtain an individual risk assessment with a travel medicine physician to determine both their risk of exposure to malaria and their need for appropriate preventive anti-malarial treatment as determined by their travel itinerary and medical history.

While no vaccine is available, there are several drugs for the prevention of malaria. Antimalarial medications decrease the risk of developing symptomatic malaria; however, they do not provide 100% protection against the disease. In most cases, antimalarial medication must be taken both before and after travel. As with all drugs, these drugs can have potential side effects and contraindications. With an individual risk assessment the appropriate preventive anti-malarial medication for each traveller can be determined. Each drug has its own dosing regime that should be strictly followed.

Multi-drug resistant strains of malaria are now common in several regions of the world. Because of these strains, medications for the prevention and/or treatment of malaria will differ. For instance, there is widespread resistance of P. falciparum to the antimalarial drug cholorquine in all malarious areas except the Caribbean, Central America (west of the Panama Canal) and parts of the Middle East.

There are many misconceptions about malaria. The prevention of malaria in travellers through the use of prophylactic drugs (including mefloquine) does not lead to the development of drug-resistant malaria parasites. When preventive drugs are appropriately used, they can actually reduce the disease's resistance to treatment by lowering the overall number of cases of malaria.

Travellers may receive conflicting information about antimalarial drugs while they are overseas. However, it is essential that travellers who have been prescribed medication continue to take it according to directions unless they experience moderate to severe adverse effects. In such cases, travellers should seek medical help promptly.

Children and DEET
In rare instances, application of insect repellents with DEET has been associated with seizures in young children (14 cases have been reported in over 30 years of DEET use and billions of applications every year). The actual concentration of DEET varies among repellents and can be as high as 95%. However, repellents with DEET concentrations of 10% are very effective and should last 3 to 4 hours. For children, DEET in a concentration of not more than 10% should be applied sparingly to exposed surfaces only and washed off after children come indoors.

The likelihood of adverse reactions can be minimized by the following precautions:

• Apply repellent sparingly and only to exposed skin.
• Avoid applying high concentration products.
• Avoid applying repellents to portions of children's hands that are likely to contact the eyes or mouth.
• Never use repellents on wounds or irritated skin.
• Wash repellent-treated skin after children come indoors. If a reaction to insect repellent is suspected, wash treated skin and seek medical attention.

In Canada, DEET products are not recommended for use in children less than 2 years of age. The risk of DEET use vs. the risk of exposure to life-threatening mosquito-borne diseases must be assessed by an individual's physician or travel medicine practitioner.

If an individual is prescribed an antimalarial medication, it is important that it be taken as directed in order to maximize the protective effect.

If a traveller develops a fever within three months after returning from an area where malaria occurs, he/she should seek medical advice immediately and advise the physician of his/her recent travel itinerary.

For more information...

• Malaria - Frequently Asked Questions
• For maps of malaria-endemic areas and other information about malaria, visit CATMAT's Canadian recommendations for the prevention and treatment of malaria among international travellers as published in the Canada Communicable Disease Report - Supplement (Vol. 30, June 2004).
• To learn more about the misconceptions about malaria and mefloquine, click here
• Table of Malaria Risk by Geographic Areas in Countries with Endemic Malaria, as published in the Canada Communicable Disease Report - Supplement (Vol. 30, June 2004).
• Country list: vaccination requirements and malaria situation (WHO)
• For more Know before you go! information, click here.