Malaria Prevention
Clinical Snapshot
Malaria is caused by 5 species of Plasmodium protozoa — P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi — transmitted through the bite of an infected female Anopheles mosquito, which feeds mainly between dusk and dawn.[1] P. falciparum causes the most severe disease, including cerebral malaria, and can progress rapidly to death without prompt treatment; P. vivax and P. ovale form dormant liver-stage hypnozoites that can cause relapse months to years after the original exposure, even after a fully completed course of most chemoprophylaxis agents.[2] No chemoprophylaxis regimen is completely protective and no malaria vaccine is licensed for routine traveller use in Canada, so prevention always combines a destination-appropriate drug regimen with rigorous mosquito-bite avoidance — and every traveller must understand that fever during or after travel to an endemic area is a medical emergency requiring urgent testing, not presumptive self-treatment.
Recognize the Condition
Typical presentation
Fever is the cardinal symptom and may be accompanied by chills/rigors, headache, myalgia, fatigue, nausea, vomiting, or diarrhea — a presentation easily mistaken for a nonspecific viral illness or another travel-associated infection (dengue, typhoid, and traveller's diarrhea all overlap symptomatically). Malaria must always be actively tested for and excluded first in a febrile returned traveller given its potential lethality, regardless of what else is on the differential.[1]
Classic cyclical fever patterns (every 48 or 72 hours) are unreliable, especially early in infection or in a partially immune or partially treated patient, so their absence never excludes malaria. Incubation is typically 7 days or more after the infective bite for P. falciparum (rarely under 6 days), but can be substantially longer for other species, and P. vivax/P. ovale hypnozoites can cause symptomatic relapse many months to several years after the traveller has left the endemic area and completed a full course of chemoprophylaxis — agents other than primaquine (and, where available, tafenoquine) do not eliminate this dormant liver stage.[2]
The 5 Plasmodium species that infect humans
P. falciparum
The most dangerous species and the cause of essentially all malaria deaths. Causes cerebral malaria, severe anemia, acute kidney injury, and multi-organ failure. No dormant liver stage.
P. vivax
Widely distributed outside sub-Saharan Africa. Forms dormant liver hypnozoites that cause relapse; usually — though not always — less immediately severe than falciparum.
P. ovale
Less common; also forms hypnozoites and can relapse. Concentrated in West Africa.
P. malariae
No hypnozoite stage, but can persist at very low, sometimes undetectable parasitemia for years and recrudesce.
P. knowlesi
A zoonotic species acquired from long-tailed and pig-tailed macaques in Southeast Asia; can progress to severe disease as quickly as P. falciparum because of its short, 24-hour replication cycle.
Risk Factors
- Travel to a malaria-endemic destination without pretravel consultation, or without chemoprophylaxis when it is indicated.
- Nonadherence to a prescribed chemoprophylaxis regimen, including stopping it early after returning home.
- Travel to West Africa or Oceania, which carry the highest transmission risk; travel to other parts of sub-Saharan Africa, South Asia, or South America, which carry intermediate risk.
- Visiting friends and relatives (VFR travellers) — this group is disproportionately affected, in part because pretravel consultation rates are lower and in part because partial immunity acquired in childhood wanes within a few years of leaving an endemic area and does not reliably protect against infection or severe disease on a return visit.
- Rural travel, travel during peak transmission season, and travel to lower-altitude areas within an endemic country, all of which raise risk compared with urban or high-altitude travel in the same country.
- Long-term travel or expatriate living in an endemic area, which raises cumulative exposure and the risk of running out of a reliable medication supply.
- Pregnancy, which increases both the likelihood of being bitten (Anopheles mosquitoes are more attracted to pregnant than nonpregnant people) and the severity of infection if it occurs.
- Young children, particularly under 5 years of age, who are at disproportionately higher risk of severe disease and death from P. falciparum malaria.
- Inconsistent or absent bite-prevention measures during exposure hours (dusk to dawn).
Red Flags & Refer
Any of the following is a medical emergency:
- Fever during travel, or at any time within 1 year of leaving a malaria-endemic area — especially within the first 3 months — must be treated as malaria until proven otherwise, regardless of chemoprophylaxis adherence and regardless of how mild the symptoms seem. Obtain an urgent thick and thin blood smear and, where available, a rapid diagnostic test the same day; do not wait for a scheduled outpatient visit.[3]
- A single negative blood smear or rapid test does not rule out malaria — if clinical suspicion remains, repeat testing at intervals over the next 48 hours rather than reassuring the patient after one negative result.[2]
- Any sign of severe/complicated malaria needs immediate hospitalization for parenteral therapy: impaired consciousness, seizures, or other neurologic signs (cerebral malaria); respiratory distress; jaundice; oliguria or acute kidney injury; spontaneous bleeding; severe anemia; hypoglycemia; circulatory collapse or shock; or a high parasite density on smear.
- Fever after malaria-endemic travel in a pregnant patient needs the same urgent testing plus immediate combined infectious disease/obstetric involvement, given the elevated maternal and fetal risk of malaria in pregnancy.
- A traveller requesting standby emergency malaria medication, or chemoprophylaxis, without any documented pretravel risk assessment should be referred for a proper travel-medicine consultation rather than dispensed to empirically.
Assessment & Diagnosis
Pretravel risk assessment
Take a detailed itinerary — specific countries, regions or cities, dates of travel, urban versus rural exposure, elevation, and planned accommodations and activities — since malaria risk varies substantially within a single country and even within a single region by season.[1]
Verify current destination-specific risk and resistance patterns against the Public Health Agency of Canada or CDC's country-by-country malaria pages before every trip, since risk areas and resistance patterns are revised periodically and are more precise than any static reference table.[2]
Also collect: age and weight (for pediatric dosing), pregnancy/breastfeeding status, current medications and known drug interactions, seizure or psychiatric history, cardiac conduction history, renal function, known G6PD status, and drug allergies — all of these can change which chemoprophylaxis agent is appropriate.
Post-travel diagnostic testing
Thick and thin blood smear microscopy remains the reference standard: the thick smear is more sensitive for detecting parasites, and the thin smear allows species identification and quantification of parasite density, both of which guide treatment intensity and monitoring.[4]
A rapid diagnostic test (RDT) can support same-day triage where microscopy is not immediately available, but does not replace microscopy for species confirmation and parasite density.
If the first test is negative but clinical suspicion remains, repeat smears at intervals over the next 48 hours rather than excluding malaria after a single negative result — early or low-density parasitemia can be missed on an initial smear.[2]
When testing is not indicated
Routine pretravel or post-travel malaria testing in an asymptomatic traveller is not indicated — testing is reserved for travellers who develop fever or other compatible symptoms during or after travel.
Treatment Targets
- Accurately assess destination- and itinerary-specific malaria risk before every trip to an endemic area.
- Select an effective chemoprophylaxis regimen matched to the destination's resistance pattern and to the traveller's individual factors (pregnancy, age/weight, G6PD status, seizure/psychiatric history, renal function, drug interactions).
- Maximize protection against mosquito bites as a mandatory adjunct to, never a substitute for, chemoprophylaxis.
- Ensure travellers to remote areas have a standby emergency treatment plan when medical care will not be reachable within 24 hours of fever onset.
- Ensure every traveller understands that fever during or after travel is a medical emergency requiring immediate malaria testing.
Choose Initial Treatment
Step 1 — confirm chemoprophylaxis is actually needed
Before recommending any drug, confirm the itinerary genuinely includes malaria-transmission risk — many popular destinations (much of Asia outside South/Southeast Asia, most of the Caribbean, and many high-altitude or purely urban itineraries) carry negligible or no risk and need only bite-prevention counselling, not chemoprophylaxis. Verify the current destination-specific recommendation via the Public Health Agency of Canada or CDC country pages before every trip, since resistance patterns and risk areas are revised periodically.[2]
Step 2 — select the agent by destination resistance pattern
Destination determines the resistance pattern, which determines which agents are appropriate for that trip:[2]
Chloroquine-sensitive destinations
Includes Central America north of the Panama Canal, Haiti, the Dominican Republic, and limited parts of Mexico — always confirm the current country/region list before travel, since this changes.
Preferred atovaquone-proguanil.
Alternative hydroxychloroquine — chloroquine itself is no longer commercially available in Canada, so hydroxychloroquine is used in its place and has comparable efficacy in these destinations.
Chloroquine-resistant destinations
The majority of malaria-endemic destinations, including the Indian subcontinent, most of Asia, South America, and sub-Saharan Africa.
Preferred atovaquone-proguanil.
Alternative mefloquine or doxycycline.
Chloroquine- and mefloquine-resistant destinations
Limited to specific border areas of the Greater Mekong Subregion — parts of Cambodia, Laos, Myanmar, Thailand, and Vietnam, and the Yunnan and Guangxi Zhuang regions of China — mefloquine remains effective across much of the rest of these countries, so confirm the exact current border-area boundaries before travel.
Preferred atovaquone-proguanil.
Alternative doxycycline.
Avoid mefloquine specifically in this region — resistance is established here.
Step 3 — when several agents are suitable for the same destination
Preferred atovaquone-proguanil over mefloquine or doxycycline whenever more than one option is medically suitable for the traveller — this is CATMAT's current (May 2025) discretionary recommendation, based on fewer treatment discontinuations and fewer non-serious neuropsychiatric side effects with atovaquone-proguanil than with mefloquine, alongside comparably high protective efficacy across all 3 agents.[2]
The same atovaquone-proguanil preference now applies even in chloroquine-sensitive destinations — CATMAT suggests atovaquone-proguanil over hydroxychloroquine, mefloquine, or doxycycline there too, when several are suitable.[2]
Atovaquone-proguanil is contraindicated in severe renal impairment (creatinine clearance under 30 mL/min) and is not recommended in pregnancy — select mefloquine or hydroxychloroquine instead, per the destination's resistance pattern, in these situations.
Step 4 — start timing (each agent is different)
Atovaquone-proguanil: start 1-2 days before entering the endemic area.
Doxycycline: start 1-2 days before entering the endemic area.
Mefloquine: start at least 1 week before entering the endemic area; where the itinerary allows more lead time, starting 2-3 weeks before is reasonable practice so any intolerable neuropsychiatric or other adverse effect can be identified and the regimen switched before departure. For travel departing in under 1 week, a loading dose (250 mg PO once daily for 3 consecutive days, then 250 mg once weekly) achieves protective levels faster.[2]
Hydroxychloroquine: start at least 1 week before entering the endemic area.
Primaquine (primary prophylaxis, used only when other agents are contraindicated or not tolerated — see below): start 1-2 days before entering the endemic area.
Step 5 — stop timing after leaving the endemic area (never shorten this)
Atovaquone-proguanil and primaquine act at the liver (causal) stage as well as the blood stage, so both can be stopped just 7 days after leaving the endemic area.
Doxycycline, mefloquine, and hydroxychloroquine act only at the blood stage — none of them clears the parasite during the roughly 1-2 week liver-stage incubation window, so all 3 must be continued for a full 4 weeks after leaving the endemic area. Stopping early is one of the most common preventable causes of prophylaxis failure, because it leaves the traveller unprotected during exactly the window when liver-stage parasites are maturing and about to enter the bloodstream.[2]
Primaquine anti-relapse (terminal) therapy — a separate decision from primary chemoprophylaxis
Offer primaquine anti-relapse therapy (also called presumptive anti-relapse therapy, PART, or terminal prophylaxis) to travellers with G6PD activity confirmed normal who are returning after an extended stay of 6 months or more in an area where P. vivax or P. ovale predominate, and to any traveller with a history of P. vivax or P. ovale infection — these 2 species form dormant liver hypnozoites that are not cleared by hydroxychloroquine, atovaquone-proguanil, doxycycline, or mefloquine, and can cause relapse from 30 days up to several years after the original exposure.[2]
Give primaquine 30 mg base (2 tablets) PO once daily for 14 days, timed either during the final 2 weeks of the traveller's primary chemoprophylaxis course or immediately after completing it — this is given in addition to, not instead of, the primary agent.[4]
Do not give primaquine to any traveller without documented G6PD testing — see Special Populations for the testing requirement.
Standby emergency self-treatment (SBET) — for remote travel only
Arrange a standby emergency self-treatment plan only for travellers going to remote, malaria-endemic areas where professional medical care will not be reachable within 24 hours of fever onset — SBET is not a substitute for chemoprophylaxis, and it is not offered to travellers with reasonable access to care.[5]
In Canada, atovaquone-proguanil at treatment dose (1,000 mg atovaquone/400 mg proguanil, 4 tablets, once daily with fatty food for 3 days) is the most practical SBET option, used only when it is not already the traveller's chemoprophylaxis agent.[6]
Never select an SBET drug from the same class as the traveller's chemoprophylaxis agent — discuss the alternative with a travel medicine clinic when this applies.
Artemether-lumefantrine (Coartem), the World Health Organization's first-line falciparum treatment, is not licensed for distribution in Canada — travellers who obtain it abroad for standby use should purchase it only in a country with reliable pharmaceutical regulation (for example, within the European Union or the United States), given the real risk of counterfeit antimalarials in some endemic regions.[5]
SBET is always a temporary bridge, never definitive treatment — instruct every traveller using it to take the dose only after a genuine inability to reach medical care within 24 hours of fever onset, and to seek professional evaluation as soon as possible afterward regardless of apparent symptom improvement.
Non-Pharmacologic Treatment
Bite prevention is not optional — no chemoprophylaxis regimen is completely protective
Anopheles mosquitoes feed mainly between dusk and dawn, so protective measures matter most during these hours, though daytime protection is still worthwhile.[3]
Insect repellents
Products registered in Canada containing 20-30% DEET or 20% icaridin (picaridin) are the preferred first-choice repellents and provide very high levels of protection against mosquito bites when used correctly and reapplied per label directions; p-menthane-3,8-diol (PMD, a synthetic derivative of oil of lemon eucalyptus) is a second-choice topical option for adults and children aged 3 years or older.[3] See Drug Tables for the full age-based dosing table.
If sunscreen is also needed, apply sunscreen first and allow it to penetrate the skin for 10-15 minutes before applying repellent — combination sunscreen-DEET products are best avoided, since they may reduce sun protection and increase DEET skin absorption.[3]
Bed nets and clothing
- Sleep under a bed net, preferably factory-treated with the insecticide permethrin, with proper tucking/installation.
- Most bed nets purchased in Canada have a shelf life of only about 6 months, while nets distributed in endemic countries last 3-5 years — do not rely on bringing a Canadian-purchased net for a long trip; a net sourced locally at the destination, or a long-lasting insecticide-treated net purchased for the purpose, lasts longer.[3]
- Sleep in an air-conditioned or well-screened room whenever possible, and use screening on doors, windows, and eaves to keep mosquitoes out of accommodation and work areas.
- Wear full-length, loose-fitting, light-coloured clothing during peak biting hours, with sleeves rolled down and pant legs tucked into socks or boots.
- Permethrin-treated clothing adds meaningful additional protection, though no Health Canada-approved permethrin clothing-treatment product is currently available — commercially pre-treated clothing, or products obtained through a travel medicine clinic, are the practical options.
Measures that are not effective — do not recommend these
Electronic/ultrasonic devices, repellent-impregnated wristbands or ankle bands, electrocuting "bug zapper" devices, odour-baited traps, citronella plants, oral vitamin B1 supplements, and skin moisturizers that do not contain a recommended repellent active ingredient have not been shown to be effective against malaria-transmitting mosquitoes — do not substitute any of these for a registered topical repellent, treated bed net, or appropriate clothing.[3]
Special Populations
Breastfeeding: antimalarial drug concentrations in breast milk are insufficient to protect a nursing infant, so a breastfed infant who needs chemoprophylaxis must still receive their own age/weight-appropriate dose. Hydroxychloroquine, mefloquine, and atovaquone-proguanil (for an infant weighing 5 kg or more) are all compatible with breastfeeding, as is doxycycline based on tetracycline-class breastfeeding data. Primaquine is contraindicated during breastfeeding unless both the breastfeeding parent and the infant have documented normal G6PD activity — the drug can be transferred through breast milk.[7]
Pediatrics
Dose every agent by current body weight and reweigh for any extended trip, since a growing child's dose changes over time.[8] Atovaquone-proguanil is used from 5 kg using the pediatric tablet strength (see Drug Tables for the full weight-band table). Mefloquine and hydroxychloroquine can be used at any age or weight per weight-based dosing. Doxycycline is contraindicated under age 8 for the duration required for chemoprophylaxis (typically well over 21 days once the pre-travel start and 4-week post-travel continuation are included) — it may still be used under age 8 specifically when the total course can be kept to 21 days or less and no other option is appropriate, reflecting current evidence that short courses do not cause the dental staining associated with prolonged use.[6] Primaquine primary prophylaxis is generally reserved for children age 9 and older with confirmed normal G6PD activity, used only when first-line agents are inappropriate; consult a travel medicine or infectious disease specialist for pediatric primaquine use outside this age range.[8] Tablets can be crushed and mixed with a strong-flavoured food (icing, peanut butter, jam, or infant formula) to mask taste — dispense a small surplus to cover a spat-out or vomited dose, with clear instructions on when a repeat dose is appropriate.
G6PD deficiency
Quantitative (or, where unavailable, qualitative) G6PD testing is mandatory before starting primaquine for any indication — primary prophylaxis or terminal anti-relapse therapy — since primaquine can precipitate severe, potentially life-threatening hemolytic anemia in a G6PD-deficient patient.[2] Because G6PD deficiency is X-linked, female patients can be heterozygous with intermediate enzyme activity; a positive qualitative screen in a female traveller should prompt quantitative testing before a final decision, since a qualitative test alone may not reliably classify intermediate activity.[2] Do not start primaquine in any patient with confirmed or unresolved G6PD deficiency — select an alternative agent instead. Tafenoquine, a single-dose alternative to primaquine used in the United States, carries the same G6PD hemolysis risk and mandatory testing requirement, but is not licensed or marketed in Canada and is not an option for Canadian-prescribed chemoprophylaxis.[4]
Seizure and psychiatric history
Mefloquine is contraindicated in anyone with a seizure disorder, cardiac conduction abnormality, or a history of a serious psychiatric disorder — active depression, generalized anxiety disorder, psychosis, schizophrenia, or another major psychiatric illness — given the risk of neuropsychiatric and neurologic adverse reactions that can persist after the drug is stopped. Select atovaquone-proguanil or doxycycline instead for these patients.[6]
Renal impairment
Atovaquone-proguanil is contraindicated in severe renal impairment (creatinine clearance under 30 mL/min) — use mefloquine or hydroxychloroquine instead, per the destination's resistance pattern. Review individual product information for dose adjustment of other agents in less severe renal impairment.
Monitoring & Follow-Up
Reinforce adherence at every opportunity: give travellers a written reminder of exactly when to start, and — critically — exactly when to stop each agent after return, since post-return nonadherence (stopping early) is a common, preventable cause of prophylaxis failure.[3] For a missed weekly dose (mefloquine, hydroxychloroquine) noticed within 1-2 days, take it immediately and resume the original weekly schedule; if more than 2 days late, take it immediately and resume weekly dosing from the new day. For a missed daily dose (atovaquone-proguanil, doxycycline, primaquine) noticed within 1-2 days, take it immediately and resume daily dosing from the new time — protective drug levels are less assured the longer a daily dose is delayed.[4] Ask specifically about new neuropsychiatric symptoms (vivid dreams, insomnia, anxiety, low mood, dizziness) in anyone taking mefloquine, and switch to an alternative agent immediately if these occur, ideally before departure if the timeline allows. For a traveller on long-term hydroxychloroquine (cumulative dose exceeding 100 g chloroquine-base equivalent, or more than 5 years of continuous use), arrange retinal screening every 6-12 months. For atovaquone-proguanil co-prescribed with warfarin, monitor INR more closely, since proguanil can potentiate warfarin's anticoagulant effect. Document any G6PD test result in the patient's permanent record, since it remains valid for future primaquine (or other G6PD-relevant drug) decisions and does not need to be repeated.
Common Errors to Avoid
- Assuming a traveller who grew up in or was born in an endemic area is protected by natural immunity — partial immunity wanes within a few years away and does not reliably prevent infection or severe disease.
- Prescribing or dispensing chloroquine, which is no longer commercially available in Canada — use hydroxychloroquine instead in chloroquine-sensitive destinations.
- Using atovaquone-proguanil in severe renal impairment (creatinine clearance under 30 mL/min) or in a traveller weighing under 5 kg.
- Starting mefloquine without asking about seizure history or a history of a serious psychiatric disorder.
- Stopping any blood-stage-only agent (doxycycline, mefloquine, hydroxychloroquine) before the full 4 weeks after leaving the endemic area — this is one of the most common preventable causes of prophylaxis failure.
- Starting primaquine — for primary prophylaxis or terminal anti-relapse therapy — without documented G6PD testing.
- Managing a returned traveller's fever presumptively, in either direction, without obtaining a blood smear or rapid test — malaria must be actively tested for and actively excluded, never assumed one way or the other.
- Excluding malaria on the basis of a single negative blood smear or rapid test when clinical suspicion remains.
- Forgetting to offer primaquine anti-relapse (terminal) therapy to an eligible long-term traveller or expatriate returning from a P. vivax/P. ovale-endemic area.
- Dispensing standby emergency treatment without a documented pretravel risk assessment, or choosing an SBET drug from the same class as the traveller's chemoprophylaxis agent.
- Treating chemoprophylaxis as sufficient on its own and de-emphasizing bite-prevention counselling.
Clinical Decision Algorithm
Drug Tables
How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.
Antifolate / naphthoquinone combination — chemoprophylaxis
Preferred first-line agent whenever several options are medically suitable for the destination and the traveller.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Atovaquone-proguanil | Adult prevention: 250 mg atovaquone/100 mg proguanil (1 tablet) PO once daily; start 1-2 days before travel, continue daily throughout exposure, stop 7 days after leaving Pediatric prevention, 5-8 kg: 1/2 pediatric tablet (31.25 mg/12.5 mg) PO once daily Pediatric prevention, over 8-10 kg: 3/4 pediatric tablet (46.88 mg/18.75 mg) PO once daily Pediatric prevention, 11-20 kg: 1 pediatric tablet (62.5 mg/25 mg) PO once daily Pediatric prevention, over 20-30 kg: 2 pediatric tablets PO once daily Pediatric prevention, over 30-40 kg: 3 pediatric tablets PO once daily Pediatric prevention, over 40 kg: 1 adult tablet PO once daily Standby emergency self-treatment, adult: 1,000 mg atovaquone/400 mg proguanil (4 tablets) PO once daily for 3 days | Nausea, vomiting, diarrhea, abdominal pain, headache | May potentiate the anticoagulant effect of warfarin — monitor INR | Take with a fatty meal or milky drink for adequate absorption. Contraindicated in severe renal impairment (CrCl under 30 mL/min) and not recommended in pregnancy. Causal plus suppressive activity allows the shorter 7-day post-travel stop.[2] |
Tetracyclines — chemoprophylaxis
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Doxycycline | Adult: 100 mg PO once daily; start 1-2 days before travel, continue daily, stop 4 weeks after leaving Pediatric, age 8 years and older: 2 mg/kg (base) PO once daily, maximum 100 mg/day; same start/stop timing Pediatric, under 8 years (only when no other option is appropriate): Same weight-based dose, limited to a total course of 21 days or less, given current evidence that short courses do not cause dental staining | Photosensitivity, GI upset, esophagitis if taken without enough fluid, candida vaginitis | Reduced levels with concurrent phenytoin, carbamazepine, or barbiturates; may reduce the effectiveness of the oral typhoid vaccine (Ty21a) if given within 3 days | Take with food and a full glass of water; remain upright for 30-60 minutes afterward. Use sunscreen given the photosensitivity risk. Contraindicated in pregnancy and breastfeeding.[6] |
Quinoline derivatives — chemoprophylaxis
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Mefloquine | Adult: 250 mg PO once weekly; start at least 1 week before travel (2-3 weeks preferred when the itinerary allows, to identify intolerance before departure), continue weekly, stop 4 weeks after leaving Late-departure loading dose (departing in under 1 week): 250 mg PO once daily for 3 days, then 250 mg once weekly Pediatric, up to 10 kg: 5 mg/kg PO once weekly Pediatric, over 10-20 kg: 62.5 mg (1/4 tablet) PO once weekly Pediatric, over 20-30 kg: 125 mg (1/2 tablet) PO once weekly Pediatric, over 30-45 kg: 187.5 mg (3/4 tablet) PO once weekly Pediatric, over 45 kg: 250 mg (1 tablet) PO once weekly | Dizziness, nausea, vomiting, headache, vivid dreams/nightmares, insomnia, mood changes, anxiety; rare seizures, psychosis, persistent vestibular symptoms | Avoid with other drugs that prolong cardiac conduction (beta-blockers, calcium channel blockers, phenothiazines, antihistamines, tricyclic antidepressants); do not combine with chloroquine or halofantrine | Contraindicated with seizure disorder, cardiac conduction abnormality, or a history of serious psychiatric illness. Take with food and a full glass of water. Preferred agent in pregnancy for chloroquine-resistant destinations.[2] |
| Hydroxychloroquine | Adult: 400 mg salt (310 mg base) PO once weekly; start at least 1 week before travel, continue weekly, stop 4 weeks after leaving Late-departure loading dose: 800 mg salt PO in 2 divided doses 6 hours apart Pediatric: 6.5 mg/kg salt (5 mg/kg base) PO once weekly, maximum 400 mg salt/dose | Pruritus (notably in patients with darker skin pigmentation — not indicative of allergy), nausea, headache, blurred vision; retinal toxicity with high cumulative dose | Avoid in epilepsy or generalized psoriasis, which it may exacerbate | The practical Canadian substitute for chloroquine, which is no longer commercially available. Retinal screening every 6-12 months if used continuously beyond 5 years. Take with food.[6] |
8-Aminoquinolines — special-situation chemoprophylaxis and anti-relapse therapy
Reserved for when other agents are contraindicated or not tolerated (primary prophylaxis), or added specifically to clear dormant liver hypnozoites (terminal anti-relapse therapy). Mandatory G6PD testing before any use.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Primaquine — primary prophylaxis | Adult: 30 mg base PO once daily; start 1-2 days before travel, continue daily, stop 7 days after leaving Pediatric, age 9 years and older, G6PD-normal: 0.5 mg base/kg PO once daily, maximum 30 mg/day; same start/stop timing | Hemolysis if G6PD-deficient, GI upset, rare methemoglobinemia | Increased methemoglobinemia risk with dapsone or other oxidant drugs | Mandatory quantitative (or qualitative, if quantitative unavailable) G6PD testing before use. Contraindicated in pregnancy; contraindicated in breastfeeding unless both parent and infant have confirmed normal G6PD activity. Take with food.[2] |
| Primaquine — terminal anti-relapse therapy (PART) | Adult: 30 mg base PO once daily for 14 days, started during the final 2 weeks of primary chemoprophylaxis or immediately after completing it Pediatric, G6PD-normal: 0.5 mg base/kg PO once daily for 14 days, maximum 30 mg/day | Hemolysis if G6PD-deficient, GI upset | Increased methemoglobinemia risk with dapsone or other oxidant drugs | Given in addition to (not instead of) the primary chemoprophylaxis agent, for extended stays of 6 months or more in a P. vivax/P. ovale-predominant area, or after any history of P. vivax/P. ovale infection. Same G6PD requirement as primary prophylaxis.[2] |
Bite prevention — insect repellents and treated barriers
Mandatory adjunct to chemoprophylaxis, not an alternative to it. Health Canada-registered products only.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| DEET (N,N-diethyl-m-toluamide) | Under 6 months: Not recommended — use a mosquito net over the crib/carrier instead 6 months to 2 years: 10% concentration, applied once daily 2 to 12 years: 10% concentration, applied up to 3 times daily Over 12 years and adults: Up to 30% concentration (do not exceed 33%), reapplied per label directions | Skin irritation with overuse; rare neurologic toxicity reported only with gross misuse or ingestion | None significant at recommended topical use | First-choice repellent alongside icaridin.[9] |
| Icaridin (picaridin) | Under 6 months: Not recommended 6 months and older, including adults: 20% concentration, applied every 8 hours | Skin irritation with overuse | None significant | Preferred over DEET in young children given the lack of odour and greasiness; comparable protection to DEET.[9] |
| P-menthane-3,8-diol (PMD) | Under 3 years: Not recommended 3 years and older, including adults: Second-choice option; follow the product label's concentration/reapplication instructions | Skin irritation with overuse | None significant | Second-choice topical repellent when DEET/icaridin cannot be used. Do not use the unformulated essential-oil version of oil of lemon eucalyptus.[9] |
| Permethrin — for treating bed nets and clothing only (not the topical anti-scabies/anti-lice cream product in the Drug Database, which is a different formulation and use) | Bed nets: Factory-treated net, properly tucked and installed Clothing: Factory pre-treated clothing preferred over home treatment | Minimal systemic absorption when used to treat fabric rather than applied to skin | None significant | No Health Canada-approved permethrin clothing-treatment product currently exists in Canada; use factory pre-treated bed nets/clothing or a product obtained through a travel medicine clinic. Most Canadian-purchased nets have a shelf life of about 6 months, versus 3-5 years for nets distributed in endemic countries — do not rely on bringing a Canadian net for a long trip. |
References
- Chapter 2: Prevention and risk assessment — CATMAT, Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria
- Chapter 4: Prevention — Chemoprophylaxis regimens — Committee to Advise on Tropical Medicine and Travel (CATMAT), Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria — last complete chapter revision May 2025
- Chapter 3: Prevention — Bite protection measures and malaria education — CATMAT, Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria
- Malaria — Centers for Disease Control and Prevention. CDC Yellow Book 2026: Health Information for International Travel
- Chapter 5.3: Malaria issues in special hosts — Long-term traveller or expatriate — CATMAT, Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria
- Chapter 8: Drugs for the prevention and treatment of malaria — CATMAT, Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria
- Chapter 5.2: Malaria issues in special hosts — Pregnancy and breastfeeding — CATMAT, Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria
- Chapter 5.1: Malaria issues in special hosts — Children — CATMAT, Public Health Agency of Canada. Canadian recommendations for the prevention and treatment of malaria
- Personal insect repellents — Health Canada, Pest Management Regulatory Agency. Government of Canada
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.