Public Health Agency of Canada
Symbol of the Government of Canada

November 2004
For Immediate Release

Frequently Asked Questions

Malaria

Malaria is a common and life-threatening disease in many tropical and subtropical areas. The World Health Organization (WHO) reports that malaria is currently endemic (i.e., constantly occurring) in over 100 countries, which are visited by more than 125 million international travellers annually. According to the WHO, many international travellers fall ill with malaria each year while visiting countries where the disease is endemic, and well over 10,000 travellers fall ill with malaria after returning home.

Q. What is malaria?

Malaria is an acute flu-like illness caused by one of four species of parasite of the genus Plasmodium: Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. Infection with P. falciparum can be fatal. Infection with P. vivax and P. ovale, while not fatal, can remain dormant in the liver for many months, thus delaying symptoms for several months or causing relapses of malaria infection.

Q. How do you get malaria?

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.

When an Anopheles mosquito ingests blood from a malaria-infected person, malaria parasites develop in the mosquito and migrate into the mosquito's salivary glands. When the infected mosquito bites another human, malaria can be transmitted to that individual.

While rare, the malaria parasite can also be transmitted by transfusion with infected blood, by shared needle use, or from a mother to her unborn child.

Q. Where is malaria found in the world?

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

Canadian travellers do get infected with malaria. 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.

Q. What are malaria's symptoms?

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 with symptoms such as 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 and can cause seizures, coma, kidney failure and respiratory failure, which can lead to death.

You must seek medical attention as soon as possible for any unexplained fever that arises during or after travel to an area where malaria occurs. Progression from malaria infection with no symptoms to severe and complicated malaria can be extremely rapid, with death occurring within 36 to 48 hours. The symptoms of malaria are non-specific, so an accurate diagnosis is not possible without a blood test. You should request that a blood film (thick and thin films) be examined for malaria parasites.

Q. How is malaria treated?

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

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.

Q. What preventive measures can be taken?

The Public health Agency strongly recommends that you obtain an individual risk assessment with a travel medicine physician or your family physician to determine both your risk of exposure to malaria and your need for appropriate preventive anti-malarial treatment as determined by your travel itinerary and medical history.

In general, two important measures can help prevent malaria infection: avoiding mosquito bites and using EFFECTIVE antimalaria medication.

1) Prevent bites

  • Avoid mosquitoes by staying in an insect-proof area during the period of the day when mosquitoes bite.
  • Prevent the bites of mosquitoes through physical barriers, such as clothing and bed nets, and chemical barriers such as the use of repellents and insecticides.
  • Wear long-sleeved shirts (tightly weaved material, sleeves down, buttoned/zipped up, tucked into pants) and long pants (tucked into socks or footwear).
  • Light-coloured clothing may be less attractive to some mosquitoes and make mosquitoes more noticeable.
  • Sleep under a mosquito net. The treatment (impregnation) of mosquito netting with insecticide (e.g., permethrin) substantially increases the protection of the net.
  • Use DEET-based products as repellents. The higher the concentration of DEET in the repellent formulation, the longer the duration of protection. However, this relation reaches a plateau at about 30% to 35%. DEET formulations that are "extended duration" (ED), or microencapsulated, provide longer protection times, likely with less DEET absorption. ED DEET is also more cosmetically acceptable. Formulations over 30% are not currently available in Canada, although they are available internationally, including in the United States. It should be noted, however, that products sold outside Canada have not been evaluated by Health Canada. Most repellents containing "natural" products are effective for shorter durations than DEET and for this reason are not considered the preferred products for protecting against mosquito bites.
  • Children travelling to malaria-endemic areas are at special risk, and extra diligence is recommended. Alternative personal protective measures, such as insecticide-impregnated mosquito nets, should be the first line of defence, especially for infants less than 6 months of age. Portable mosquito nets, including self-standing nets, placed over a car seat, a crib, playpen, or stroller provide an insect-protected environment for infants. However, as a complement to the other methods of protection, the judicious use of DEET should be considered for children of any age. Recent medical literature from Canada suggests that DEET does not pose a significant or substantial extra risk to infants and children.

2) Use antimalaria medication

While no vaccine is available, effective antimalarial medications decrease the risk of developing symptomatic malaria. However, they do not provide 100% protection against the disease. The type of antimalarial medication you should use depends, in part, on the areas you will visit. The Public Health Agency provides guidance on the range of antimalarial drugs available in its publication, Canadian Recommendations for the Prevention and Treatment of Malaria Among International Travellers.

  • In most cases, you must take antimalarial medication both before and after travel.
  • Each drug has its own dosing regime that you must strictly follow. With an individual risk assessment, you can receive the appropriate preventive anti-malarial medication for your needs.

Remember: If you develop a fever during travel to a malaria-endemic area or within three months after returning from an area where malaria occurs, seek medical advice immediately and advise the physician of your recent travel itinerary.

Travel Health