Malaria, a parasite infection transmitted by the nocturnal anopheles mosquito, is a leading cause of illness and death in the tropics. For the non-immune traveller, malaria poses a serious threat because of the rapid development of disease, drug-resistant strains, and the inherent limitation of medications for both prevention and treatment.


Symptoms will not be apparent for a minimum of one week after exposure (incubation period). Malaria can, however, develop weeks or months after leaving a malaria zone. The most consistent symptom is a high fever. Other symptoms include a severe headache and muscle pains, similar to the common “flu.”

If you have travelled to the tropics it is wise to assume that any flu-like illness is malaria for at least 3 months following your return.


No preventive treatment offers absolute protection. Drugs alone can no longer be relied upon for absolute malaria prevention.

  1. Protect yourself from mosquito bites.
    • Wear clothing that covers your arms and legs from dusk to dawn.
    • Apply mosquito repellent to exposed skin (DEET).
    • Reduce outdoor activity in the evenings.
    • Screen your bed with a nylon, insecticide-treated net.
    • Treat clothing with permethrin, a colourless, odourless, tasteless mosquito toxicant (not licensed for this purpose in Canada)
  2. Preventive treatment
    • Antimalarial drugs are prescribed to reduce the infection rate and the threat of death.
      • Atovaquone/proguanil (Malarone) and primaquine act during the incubation (liver) phase of the infection
      • Chloroquine, doxycycline, and mefloquine will only act during the phase when the red blood cells become infected.
    • Take only as prescribed prior to your arrival in a malaria region, continuing throughout your stay, and following your departure from the area of risk.
    • See table for details.
Drug Adult Dose Pediatric Dose Side effects

Start 1 day prior to entering malarial area and continue until 7 days after departure
1 tablet daily 11-20 kg: 1 pediatric tablet daily
> 20 - 30 kg: 2 pediatric tablets daily (as single dose)
> 30-40 kg: 3 pediatric tablets daily (as single dose)
> 40 kg: 1 adult tablet daily
Frequent: nausea, vomiting, abdominal pain, diarrhea, mouth ulcers

Rare: seizures, rash, hepatitis

Note: 1 tablet = 155 mg of base

Start 1 week prior to entering malarial area and continue until 4 weeks after departure
310 mg base once weekly Once weekly dose

< 15 kg: 5 mg base/kg
15 - <20 kg: 1/2 tablet
20-<25 kg: 3/4 tablet
25-<35 kg: 1 tablet
35-50 kg: 1 1/2 tablets
> 50 kg: 2 tablets
Frequent: nausea, headache

Occasional: rash

Rare: nail and mucous membrane discoloration, hair loss, photophobia, nerve deafness, psychosis, and seizures

Start 1 day prior to entering malarial area and continue until 4 weeks after departure
1 tablet (100 mg) once daily 2 mg base/kg once daily (max 100 mg daily) Frequent: Gastrointestinal upset, vaginal yeast infections, photosensitivity

Rare: Allergic reactions, esophageal ulceration
(Lariam, Apo-Mefloquine)

Start at least 1 week (preferably 2-3 weeks) prior to entering malarial area and continue until 4 weeks after departure
250 mg once weekly Once weekly:
5-10 kg: 1/8 tablet
> 10-20 kg: 1⁄4 tablet
> 20-30 kg: 1⁄2 tablet
> 30-45 kg: 3⁄4 tablet
> 45 kg: 1 tablet
Frequent: Dizziness, headache, sleep disorders, vivid dreams, nausea

Occasional: Confusion, hallucinations, forgetfulness, restlessness, emotional problems (including anxiety, agitation, mood changes)

Rare: Suicidal ideations, seizures, psychosis

Start at least 1 day prior to entering malarial area and continue until 7 days after departure
30 mg base daily 30 mg base daily Occasional: Gastrointestinal upset

Rare: damage to red blood cells in G6PD deficient individuals

* Can only be prescribed after determining that the G6PD level is normal; prescribing physician will order this test unless previously documented to be normal.


  • If a fever develops, seek prompt medical attention. It is impossible to make an accurate diagnosis based on symptoms alone. Delays before beginning appropriate therapy can have serious or even fatal consequences.

For More Information

Public Health Agency of Canada:

World Health Organization:

Committee to Advise on Tropical Medicine and Travel:

World Health Organization:

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Since 1936, International Medical Services (IMS) has strategically promoted safety and travel illness prevention. We have extensive experience sending short and long term expatriates to every continent and major travel destination (including Antarctica).

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