What Is Malaria?

Malaria is a parasitic infection of the red blood cells caused primarily by Plasmodium falciparum and P. vivax. It is transmitted through the bite of Anopheles mosquitoes, which generally feed between dusk and dawn. Malaria occurs in approximately 90 countries, mostly in Africa, but also in Central and South America, South Asia, Southeast Asia, the Middle East, and South Pacific islands.

Where Is Malaria a Risk?

Risk is much higher in sub-Saharan Africa, eastern Indonesia, and Papua New Guinea than anywhere else. In most parts of the world, malaria is a rural disease with minimal or no risk in urban areas. However, in sub-Saharan Africa and South Asia, malaria risk occurs in both rural and urban areas. Malaria does not occur above 2,500 m elevation, during dry seasons, or among persons who stay in air-conditioned and screened accommodations.

Risk Factors for Travellers

Risk varies greatly within a country depending on the intensity of transmission, your itinerary, season, duration and type of travel, location (urban vs. rural), and where you spend the evening and nighttime hours. Short-stay travellers visiting urban centres and staying in air-conditioned hotels will be at much lower risk than long-stay, adventurous travellers in rural areas.

Even brief exposure — such as a single overnight stay in a malarious area or a nighttime train trip through a malarious area — requires that protective measures be taken, including insect precautions and possibly a full course of antimalarial medication.

Adults who grew up in malarious areas should be aware that immunity to malaria disappears within 6 months of the last exposure. Risk is the same as for first-time travellers.

Symptoms

Symptoms most commonly develop within 10 to 14 days after exposure, but can appear weeks, months, or even a few years after leaving a malarious area. Symptoms always include fever and influenza-like illness (chills, sweats, muscle aches, headache). Vomiting, abdominal pain, diarrhea, cough, and jaundice may also occur. Because malaria symptoms can mimic almost any other fever-causing infection, anyone who develops fever after travel to a malarious area must be tested promptly.

Consequences of Infection

P. falciparum malaria can progress to shock, lung and kidney failure, coma, and death without immediate and proper treatment — it is a medical emergency. P. vivax rarely causes severe disease but can persist dormant in the liver for many months and relapse periodically until treated. Malaria is always completely curable when the appropriate drug is used promptly.

Antimalarial Medications

No vaccine is available for malaria prevention in travellers. Prevention relies on prescription antimalarial medication, personal protective measures, and prompt medical evaluation of any fever during or after travel. Four equally effective options are available:

Atovaquone-Proguanil (Malarone)

One tablet (250 mg/100 mg) taken once daily with food or milk. Start 1-2 days before entering a malaria risk area, take daily while in the risk area, and continue for 1 week after leaving. Best option for short trips under 2-3 weeks due to the short post-travel course. Side effects are uncommon but may include nausea and stomach upset. Not suitable for pregnant women or those with severe kidney failure.

Doxycycline

One 100 mg tablet taken once daily. Start 1-2 days before entering a malaria risk area, take daily while in the risk area, and continue for 4 weeks after leaving. Take with food and a full glass of water; do not lie down for 30 minutes after taking. May cause sun sensitivity — use SPF 30-50 sunscreen. Do not take antacids or Pepto-Bismol concurrently. Not suitable for children under 8 years or pregnant women.

Mefloquine

One 250 mg tablet taken once weekly. Start 2-3 weeks before entering a malaria risk area (to assess tolerability before departure), take weekly while in the risk area, and continue for 4 weeks after leaving. Preferred for long-stay travel over 6 months due to once-weekly dosing and lower cost. Do not use in Southeast Asia due to resistance. Can cause neuropsychiatric side effects (anxiety, depression, vivid dreams) — stop immediately and seek alternatives if these occur. Not suitable for persons with epilepsy, cardiac conduction abnormalities, or psychiatric history.

Tafenoquine (Arakoda)

Requires a G6PD blood test before first use — a single normal test is valid for life. Adult dose is two 100 mg tablets (200 mg total) taken once weekly. Loading dose: take once daily for 3 consecutive days before entering a malarious area. Maintenance dose: take once weekly while in the malarious area. Terminal dose: take one dose 7 days after the last maintenance dose after leaving. Cannot be used for longer than 6 months. Not suitable for persons under 18, pregnant women, those with G6PD deficiency, or those with a history of psychotic disorders.

Personal Protective Measures

Anopheles mosquitoes bite between dusk and dawn. Combine antimalarial medication with these measures:

• Wear clothing that covers as much skin as practicable during evening and nighttime hours
• Apply DEET (30-35%) or picaridin (20%+) to all exposed skin; apply sunscreen first (SPF 30-50), then repellent on top
• Treat outer clothing, boots, tents, and sleeping bag liners with permethrin in high-risk areas
• Sleep under a permethrin-impregnated bed net when at high malaria risk if not in a sealed, air-conditioned room
• Use spatial repellents (aerosol sprays, vaporizer devices, or pyrethroid coils)

When to Seek Medical Attention

Any fever or flu-like illness during or after travel to a malarious area — even months or years later — requires immediate medical evaluation. Request thick and thin blood films or a malaria rapid diagnostic test, and inform your healthcare provider of your travel history. One negative test does not rule out malaria; if symptoms persist, repeat testing 12 to 24 hours apart is needed.

Get Your Antimalarial Prescription

Our ISTM-certified travel medicine physicians assess your complete itinerary, determine your malaria risk by area, and prescribe the most appropriate antimalarial medication. Book your virtual consultation online — available evenings and weekends.

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