ISSN 1481-8531 (On-line)
by the Committee to Advise on Tropical Medicine and Travel (CATMAT)
Boggild AFootnote i, Brophy JFootnote ii, Charlebois PFootnote iii, Crockett MFootnote iv, Geduld JFootnote v, Ghesquiere WFootnote vi, McDonald PFootnote vii, Plourde PFootnote viii, Teitelbaum PFootnote ix, Tepper MFootnote x, Schofield SFootnote xi and McCarthy A (Chair)Footnote xii Footnote *
Background: On behalf of the Public Health Agency of Canada, the Committee to Advise on Tropical Medicine and Travel (CATMAT) developed the Canadian Recommendations for the Prevention and Treatment of Malaria Among International Travellers for Canadian health care providers who are preparing patients for travel to malaria-endemic areas and treating travellers who have returned ill.
Objective: To provide guidelines on malaria issues related to special hosts.
Methods: CATMAT reviewed all major sources of information on malaria prevention, as well as recent research and national and international epidemiological data, to tailor guidelines to the Canadian context. The evidence-based medicine recommendations were developed with associated rating scales for the strength and quality of the evidence.
Recommendations: All people visiting malaria endemic regions should use effective personal protective measures (PPM; topical repellants, bed nets, behavioural choices) and the prescribed chemoprophylaxis. Chemoprophylaxis for pregnant and breastfeeding women and for children requires careful consideration in the context of the pregnancy trimester, the age or size of the infant/child as well as their glucose-6-phosphate dehydrogenase (G6PD) status. Recommendations for long-term travellers, expatriates and people visiting friends and relatives (VFRs) do not differ markedly from those for short-term travellers. Some underlying medical conditions may make individuals more vulnerable to malaria. In addition, some conditions or their treatment may preclude the use of one or more antimalarial medications.
Malaria is a serious infection caused by five different species of the genus Plasmodium: falciparum, vivax, ovale, malariae and knowlesi. Malaria is transmitted by the bite of infected female anopheline mosquitoes. Infections caused by P. falciparum have the highest fatality rates. The overall case-fatality rate of falciparum malaria varies from about 1% to 5% and increases to 20% for those with severe malaria Footnote 1.
The Committee to Advise on Tropical Medicine and Travel (CATMAT) provides the Public Health Agency of Canada with ongoing and timely medical, scientific and public health advice relating to tropical disease and health risks associated with international travel. This is a summary of one section of the CATMAT Canadian Recommendations for the Prevention and Treatment of Malaria Among International Travellers developed for Canadian health care providers who are preparing patients for travel to malaria-endemic areas and treating travellers who have returned ill Footnote 2. These guidelines include a full description of the recommendations on risk assessment, prevention and treatment of malaria, a disease that is still uncommon in Canada. Two additional summaries of the guidelines are available focusing on prevention and treatment of malaria Footnote 3 Footnote 4.
Special groups of travellers have different risks of acquiring malaria infection compared with the average traveller. If unable to defer travel to areas with high risk of malaria, pregnant and breastfeeding women and small children should receive tailored antimalarial chemoprophylaxis, since some of the drugs are contraindicated in these groups. Long-term travellers, expatriates and travellers visiting friends and relatives (VFRs) may perceive malaria risk differently and may adhere differently to chemoprophylaxis. They require additional information about self-diagnosis and treatment. The issue of counterfeit drugs is addressed specifically for long-term travellers.
The Malaria Subcommittee, a working group of CATMAT, developed the guidelines. The process undertaken to develop them has been described previously Footnote 3. It included a review of recent research and national and international epidemiological data, and the consideration of other factors, such as malaria epidemiology, and the anticipated values and preferences of travellers and health care providers. The evidence-based medicine recommendations for various malaria issues pertaining to special hosts were developed with associated rating scales for the strength and quality of the evidence.
The evidence-based CATMAT recommendations for malaria prevention and treatment in special hosts are summarized in Table 1. A discussion of some of the key recommendations follows.
Malaria disproportionately affects children and can have nonspecific symptoms that mimic other common childhood illnesses, leading to delays in diagnosis. Severe or complicated malaria, such as cerebral malaria, severe anemia, shock or even death, may develop more quickly in children Footnote 5.
Young children should avoid travel to areas with significant malaria transmission, particularly of chloroquine-resistant malaria Footnote 6. When travel to malaria-endemic areas is unavoidable consider the following:
Pregnant women should defer travel to malaria-endemic areas and particularly to regions with drug-resistant falciparum malaria Footnote 15. Malaria increases the risk of maternal and neonatal death, miscarriage and stillbirth. Low birth-weight infants are more commonly born to women taking ineffective prophylaxis Footnote 15.
If travel is unavoidable,
Nursing women should continue to breastfeed if using chemoprophylaxis that is safe in infancy (chloroquine, mefloquine, atovaquone-proguanil in infants weighing ≥ 5 kg). Doxycycline absorption through breast milk is probably negligible, and breastfeeding is not an absolute contraindication to maternal use Footnote 23.
Although in most cases disease will develop within three months of last exposure, malaria could be the reason for any fever that develops within 12 months of leaving a malaria-endemic region Footnote 24. The risk of malaria exists for migrants after their arrival in Canada:
Recommendations for preventing malaria in long-term travellers (travel for longer than one month), expatriates or visiting friends and relatives are very similar to the standard recommendations for the short-term traveller Footnote 26: use prescribed malaria chemoprohylaxis and PPM consistently, including insecticide-treated bed nets and topical repellents containing 20%-30% DEET or 20% icaridin.
Some of the topics to cover when counselling expatriates and long-term travellers about malaria prevention include the following:
Since overall nonadherence rates for chemoprophylaxis are as high as 61% Footnote 27, pre-travel advice should focus on these aspects:
The risk of malaria among visiting friends and relatives is almost the same as for local residents, but the risk of severe disease is higher because of loss of partial immunity after having lived in a non-endemic area Footnote 25.
VFRs tend to show certain characteristics:
|Recommendation||EBM rating Table 1 - Footnote *|
|1.||Young children should avoid travel to areas with significant malaria transmission, particularly of chloroquine-resistant malaria Footnote 6.||C III|
|2.||All children who travel to malaria-endemic areas should use PPM Footnote 7.||A I|
|3.||In chloroquine-resistant areas, mefloquine, doxycycline (≥ 8 years) and atovaquone-proguanil (≥ 5 kg) are the drugs of choice for chemoprophylaxis Footnote 9 Footnote 10 Footnote 11 Footnote 12.||A I|
|4.||Primaquine chemoprophylaxis may be suitable for children who cannot take any of the first-line prophylactic agents, after confirmation of G6PD status Footnote 13.||B II|
|5.||Pregnant women should avoid travel to areas with significant malaria transmission Footnote 15.||C III|
|6.||Pregnant women who travel to malaria-endemic areas should use PPM, including appropriate topical repellents and insecticide-treated bed nets Footnote 16.||A I|
|7.||In chloroquine-sensitive areas, pregnant women should use chloroquine as chemoprophylaxis.||A I|
|8.||Where exposure to chloroquine-resistant falciparum malaria is unavoidable, pregnant women should use mefloquine from conception through the first trimester (A II) and during the second and third trimesters (A I) Footnote 17 Footnote 18 Footnote 19.||A II, A I|
|9.||There are no currently approved antimalarials for pregnant women travelling to mefloquine-resistant regions. Atovaquone-proguanil after the first trimester may be considered after careful discussion of the benefits and risks Footnote 20 Footnote 21.||B II|
|10.||Although safe in pregnancy, the combination of chloroquine and proguanil is inadequate as an antimalarial and cannot be recommended for chloroquine-resistant areas Footnote 22.||E I|
|11.||Infants should receive their own appropriate chemoprophylaxis even if breastfed Footnote 23.||A III|
|12.||Women breastfeeding a child < 5 kg should avoid atovaquone-proguanil Footnote 23.||C II|
|13.||Limited data suggest that doxycycline absorption through breast milk is negligible and that breastfeeding is not an absolute contraindication to maternal use Footnote 23.||C III|
|14.||For at least 12 months after migrants arrive in Canada, test for malaria in cases of unexplained fever.||C III|
|15.||Consider malaria screening in asymptomatic new arrivals from highly endemic areas, and treat those who have parasitemia (apart from the presence of gametocytes only) in blood smears.||C III|
|16.||Ask migrants from malaria-endemic countries about future travel plans. Doing so may provide the opportunity for anticipatory guidance about malaria Footnote 25.||C III|
|Long-term travellers or expatriates|
|17.||Guidelines for preventing malaria in long-term travellers or expatriates should not deviate considerably from the recommendations for short-term travellers Footnote 26.||B III|
|18.||Training long-term travellers in the use of rapid diagnostic tests is reasonable Footnote 26 Footnote 34.||C III|
|19.||For long-term travellers who are more likely to buy drugs in countries without quality controls, provide education about counterfeit antimalarial medications Footnote 35 Footnote 37.||C II|
|20.||Consider primaquine for terminal prophylaxis for military personnel, long-term travellers or expatriates returned from regions with P. vivax transmission Footnote 26 Footnote 38 Footnote 39.||A I|
|Visiting friends and family (VFRs)|
|21.||Inform Canadian VFRs travelling to malaria-endemic countries about the risk of malaria, including the loss of partial immunity from living in Canada and the increased risk of severe disease in children and pregnant women Footnote 25.||C III|
|22.||Counsel Canadian VFRs travelling to malaria-endemic countries about PPM (repellents, bed nets, behavioural choices) and chemoprophylaxis Footnote 25.||C III|
|23.||Discuss the affordability of chemoprophylaxis with Canadian VFRs travelling to malaria-endemic countries, taking cost into account in deciding about choices Footnote 25.||C III|
|Travellers with co-morbidities|
|24.||Individuals who are immunosuppressed or have co-morbidities should consult with a travel medicine or infectious disease expert Footnote 40.||B III|
|25.||Potential drug interactions and overlapping toxicities warrant careful review before antimalarial drugs are prescribed for people with chronic medical conditions, including HIV infection Footnote 41.||A I|
|26.||HIV-infected individuals who are pregnant or have advanced immune suppression should be encouraged to choose non-malaria endemic locations or defer travel until after pregnancy or restoration of immune function.||B III|
|27.||Provide standby antimalarial therapy for travellers with asplenia who may experience delays in accessing appropriate care for febrile illness.||A II|
|28.||A pre-travel trial with INR (international normalized ratio) testing should be done if mefloquine, doxycycline or proguanil (including atovaquone-proguanil) are to be used by people taking warfarin Footnote 42 Footnote 43 Footnote 44 Footnote 45.||A II|
|29.||Avoid chloroquine and mefloquine in the presence of a chronic seizure disorder.||E II|
|30.||Avoid chloroquine and mefloquine for travellers with myasthenia gravis.||E III|
|31.||Carefully review mental health history before prescribing mefloquine to ensure that psychotic, depressive or anxiety disorders are absent Footnote 46.||A I|
|32.||Chloroquine may exacerbate psoriasis. Mefloquine, doxycycline and atovaquone-proguanil are preferable to chloroquine in patients with underlying psoriasis.||B III|
|33.||Primaquine should not be used as chemoprophylaxis in the presence of G6PD deficiency.||E II|
|34.||Atovaquone-proguanil may be the preferred choice for malaria prophylaxis in the presence of porphyria.||B III|
Long-term use of chemoprophylaxis recommended for short-stay travellers does not result in additional risk of severe adverse events although data on the effectiveness and tolerance of recommended regimens are limited. Table 2 summarizes the safety of chemoprophylaxis with long-term use.
|Chemoprophylactic drug||Effects of long-term use|
|Chloroquine||Requires an ophthalmologic examination at least every 2 years Footnote 30. However, chloroquine is seldom indicated because of extensive drug resistance.|
|Mefloquine||Well tolerated Footnote 47 Footnote 48 Footnote 49 Footnote 50.
Mefloquine tolerance improves over time, possibly because any adverse events become apparent relatively early Footnote 47. Consequently, there does not appear to be increased risk with long-term use Footnote 28.
|Atovaquone-proguanil||Although data on prolonged use of atovaquone-proguanil are limited, the individual components have been used for extended periods Footnote 30.|
|Doxycycline||Although data are limited, the drug and the related minocycline have been used for extended periods for other indications Footnote 31.|
Currently, no long-lasting, insecticide-treated nets are registered for use in Canada. Insecticide-treated bed nets can be obtained from some Canadian travel health clinics and other domestic and international suppliers Footnote 8:
Many expatriates and long-term travellers may have the opportunity to buy their antimalarial chemoprophylaxis and antimalarial drugs over the counter at local pharmacies where they are staying and cannot evaluate the authenticity of these drugs. Encourage all travellers and expatriates to buy a supply of medication in countries with strict quality control measures Footnote 35 Footnote 36 Footnote 37.
If travellers are buying outside of Canada bear in mind the following:
Rapid diagnostic tests are essential diagnostic tools when malaria microscopy results are not available within two hours Footnote 26. Rapid diagnostic tests are simple to use, require no equipment or specialized laboratory skills and can be valuable adjuncts in diagnosing malaria Footnote 52. However, many travellers are unable to complete the procedures or interpret the results correctly Footnote 26 Footnote 53 Footnote 54. Without adequate training of laboratory staff, the usefulness of rapid diagnostic tests may be no better among expatriates Footnote 34 Footnote 55. Nevertheless, key members of a reasonably stable expatriate community could be trained in their use and in administration of appropriate self-treatment Footnote 26 Footnote 34.
Self-treatment is a temporary, life-saving measure for 24 hours while medical attention is sought. Travellers to high-risk regions should never rely exclusively on self-treatment Footnote 40 Footnote 56 Footnote 57 Footnote 58. Self-treatment regimens by region are summarized in Table 3.
Reasons for self-treatment include travelling/staying in these areas:
Standby malaria treatment with atovaquone-proguanil or quinine and doxycycline is recommended for travellers who are more than a day away from malaria diagnostic help.
|Chloroquine-sensitive regions||Self-treat with chloroquine and then resume or start chloroquine prophylaxis Footnote 54 Footnote 56 Footnote 60.|
|Chloroquine-resistant and/or chloroquine- and mefloquine-resistant P. falciparum regions||Self-treat with a drug different from that used for prophylaxis:|
Some antimalarials are contraindicated for the treatment of malaria (self-treatment or otherwise):
P. vivax and P. ovale parasites can persist in the liver and cause relapses for as long as five years after the person has left a malaria-endemic area. Primaquine anti-relapse therapy (PART) decreases the risk of relapses by acting against the liver stages of P. vivax and P. ovale. PART is usually administered during or after the last two weeks of chemoprophylaxis to those who have been in malaria-endemic regions (most malarial areas of the world except Haiti and the Dominican Republic) Footnote 26 Footnote 38 Footnote 39 Footnote 64. Primaquine is contraindicated for use as PART in people with G6PD deficiencies, in pregnancy and in nursing mothers if the infant is G6PD deficient.
Interactions between malaria and other underlying medical conditions may result in increased susceptibility to and severity of malaria or complications of the underlying conditions. Some underlying health conditions may be exacerbated by or preclude using one or more antimalarial medications.
Routinely undertake a drug interaction check to avoid any potential adverse drug interactions unless the traveller's medications are known to be safely used with the proposed antimalarial agent.
Immunocompromised travellers should carefully adhere to both PPM and chemoprophylaxis.
There is a significant and complex interaction between human immunodeficiency virus (HIV) and P. falciparum. Assess for drug interactions, and consider the risk of overlapping adverse effect profiles Footnote 65. CATMAT recommends consulting with a travel/tropical medicine/infectious disease expert and the traveller's HIV specialist Footnote 40.
Asplenia increases the risk, magnitude and duration of parasitemia, even among partially immune individuals in malaria-endemic countries Footnote 41, and enhances the risk of severe and fatal malaria in travellers with this condition Footnote 66. Recommend standby self-treatment in addition to prophylactic measures if the traveller is heading to remote regions and/or access to care is limited. Since fever may be due to malaria or bacterial infection, provide antibacterial standby treatment Footnote 67.
A list of other conditions and their effects on the choice of malaria chemoprophylaxis are summarized in Table 4.
|Condition||Impact on choice of malaria chemoprophylaxis|
|Abnormal coagulation||Mefloquine, doxycycline and proguanil may potentiate warfarin Footnote 42 Footnote 43 Footnote 44 Footnote 45 Footnote 68.
Conduct a medication trial several weeks in advance of travel and International Normalized Ratio (INR) serial testing to allow adjustment of the anticoagulant dose both before and after travel.
|Seizure disorders||Chloroquine and mefloquine may exacerbate seizures, so prescribe alternative agents. There is no evidence that febrile seizures in children are a contraindication for these drugs.
Concurrent use of anticonvulsant drugs that induce hepatic microsomal enzymes (e.g. barbiturates, phenytoin, carbamazepine) may decrease serum levels and the half-life of doxycycline, and may require dosage adjustment Footnote 45.
|Myasthenia gravis||Malaria infections may exacerbate myasthenia gravis. Optimal prevention through adherence to chemoprophylaxis and PPMs should be reinforced.
Avoid chloroquine, mefloquine and doxycycline as they have been associated with worsening of myasthenic symptoms. Doxycycline may be considered in stable patients, particularly for those with only ophthalmologic symptoms, though CATMAT recommends a pre-travel therapy trial. A pre-travel trial of atovaquone-proguanil therapy is recommended, since proguanil monotherapy has been reported to worsen myasthenic symptoms Footnote 69.
Primaquine has not been associated with myasthenic symptoms and may be an option for P. falciparum prophylaxis (after ruling out G6PD deficiency) in myasthenic travellers who are unable to tolerate doxycycline and atovaquone-proguanil.
|Psychiatric disorders||Assess for history of depression, generalized anxiety disorder or psychosis before prescribing mefloquine Footnote 46 Footnote 70.|
|Hepatic or renal dysfunction||Moderate to severe hepatic or renal dysfunction may alter antimalarial medication levels Table 4 - Footnote *. If necessary, consult with a travel/tropical medicine expert.
Severe renal insufficiency (creatinine clearance < 30 mL/min) is a contraindication to atovaquone-proguanil use.
|Psoriasis||Avoid chloroquine as it may trigger acute flares of psoriasis Footnote 73 Footnote 74.|
|Glucose-6-phosphate dehydrogenase (G6PD) deficiency||Primaquine is associated with a potentially life-threatening risk of hemolysis. Although G-6PD deficiency is raised as a concern by the manufacturers of chloroquine, experts do not consider this a contraindication, since significant hemolysis is unlikely at prophylactic doses.|
|Porphyria||Apart from atovaquone-proguanil Footnote 75, all the first-line malaria chemoprophylactic agents may be porphyrinogenic. Use with caution.|
Special groups of travellers require additional information for prevention and management of malaria. In addition, they should recognize the importance of adherence to recommendations for chemoprophylaxis and PPM. Treatment varies according to the species of Plasmodium, the severity of disease and the region where the malaria was acquired, as well as potential interactions between chronic medications and recommended antimalarial therapy.
CATMAT acknowledges and appreciates the contribution of Joanna Odrowaz and Elspeth Payne to the development of the summaries and Manisha Kulkarni for her contribution to the statement.
CATMAT Members: Boggild A, Brophy J, Bui YG, Crockett M, Ghesquiere W, Greenaway C, Henteleff A, Libman M, Teitelbaum P and McCarthy A (Chair).
Liaison members: Hui C (Canadian Paediatric Society) and Gershman M (US Centers for Disease Control and Prevention).
Ex-officio members: Marion D (Canadian Forces Health Services Centre, Department of National Defence), McDonald P (Division of Anti-Infective Drugs, Health Canada), Schofield S (Directorate of Force Health Protection, Department of National Defence) and Tepper M (Directorate of Force Health Protection, Department of National Defence).
Member Emeritus: Jeanes CWL.
There are no conflicts of interest to declare.
This work was supported by the Public Health Agency of Canada.