Chapter 5.3 – Malaria issues in special hosts - Long-term traveller or expatriate: Canadian recommendations for the prevention and treatment of malaria

• Previous Page
• Table of Contents
• Next Page

An Advisory Committee Statement (ACS) from the
Committee to Advise on Tropical Medicine and Travel (CATMAT)

Preamble

The Committee to Advise on Tropical Medicine and Travel (CATMAT) provides the Public Health Agency of Canada (PHAC) with ongoing and timely medical, scientific, and public health advice relating to tropical infectious disease and health risks associated with international travel. PHAC acknowledges that the advice and recommendations set out in this statement are based upon the best current available scientific knowledge and medical practices, and is disseminating this document for information purposes to both travellers and the medical community caring for travellers.

Persons administering or using drugs, vaccines, or other products should also be aware of the contents of the product monograph(s) or other similarly approved standards or instructions for use. Recommendations for use and other information set out herein may differ from that set out in the product monograph(s) or other similarly approved standards or instructions for use by the licensed manufacturer(s). Manufacturers have sought approval and provided evidence as to the safety and efficacy of their products only when used in accordance with the product monographs or other similarly approved standards or instructions for use.

Chapter 5: Malaria issues in special hosts

5.3 Prevention in special hosts—long term or expatriate

Preventing malaria in the long term traveller or expatriate

The particular concerns that relate to preventing malaria in long-term travellers (those who travel for more than one month) and expatriates include: safety of chemoprophylactic drugs and fear of toxic effects with prolonged use of medication; cost of long-term medication; use of locally procured drugs that may be counterfeit; conflicting counsel about appropriate chemoprophylaxis and self- treatment; and lack of adherence to chemoprophylaxis and personal protective measures (PPM).

Modern prevention strategies have had a significant positive impact on the risk of malaria-related mortality in long-term expatriates. Mortality was reported to be as high as 60% among missionaries in West Africa during the 20th century^{Reference 1}. However, developing unique, evidence-based guidelines for the long-term traveller or expatriate has been limited by a lack of medical literature in this area, as well as the variability in risk based on location, occupation, lifestyle and activities^{Reference 2}. The risk of malaria associated with location, or the entomological inoculation rate, may vary depending on the season, as well as whether the location is rural, peri-urban or urban.

The advice of health care providers may compete with the opinions of travellers who assume that their personal experience with drug-related adverse events is representative of the general population^{Reference 3}. Some researchers have observed that the incidence of malaria may be greater among veteran expatriates than among their less experienced counterparts. The veteran expatriates may have unreasonable confidence in their clinical self-diagnosis^{Reference 4} compounded by false-positive laboratory errors^{Reference 5}. The use of counterfeit drugs can also lead to drug resistance or, more immediately, treatment failures. Users may then generalize the resultant failure of response of a specific medication to all malaria medications^{Reference 6}.

Adverse events

A survey of over 2,700 Peace Corps volunteers found that 62% reported one or more adverse events, with 9% reporting serious adverse events and 23% changing malaria prophylaxis due to adverse events^{Reference 7}.

There is no evidence to suggest that long-term use of therapies currently recommended for short-stay travellers results in additional risk of severe adverse events. Chloroquine may be an exception; the risk of chloroquine retinopathy requires an ophthalmologic exam at least every two years for travellers using chloroquine long-term^{Reference 8}. However, this drug is seldom indicated because of extensive drug resistance. Although the data supporting long-term use of doxycycline for chemoprophylaxis are limited, the drug and the related minocycline is in use for extended periods of time for other indications^{Reference 9}.

Mefloquine tolerance improves over time, possibly associated with the relatively early onset of adverse events experienced by those who use mefloquine for prophylaxis^{Reference 5}. Consequently, there does not appear to be increased risk with long-term use^{Reference 10}. Although there are few data on prolonged use of atovaquone-proguanil, the individual components have been used for extended periods of time^{Reference 8}.

Current malaria prevention practice among expatriates

Malaria chemoprophylaxis use in expatriates is suboptimal. Only 69% of expatriate households in Nigeria appropriately picked up their chemoprophylaxis from the pharmacy, and among those that did, 58% were nonadherent, resulting in an overall nonadherence rate of 61%^{Reference 11}. A study of expatriates in western Ghana found that duration of stay was inversely proportional to adherence to malaria chemoprophylaxis; 80% of those who had been in western Ghana for three months or less were taking malaria chemoprophylaxis, compared to none of the workers who had been there for over a year^{Reference 12}. A review of health behaviours among expatriate workers for the International Committee of the Red Cross reported 65% adherence to recommended malaria chemoprophylaxis^{Reference 13}. Finally, a survey of expatriate health care workers in Equatorial Guinea found that only 31% adhered to their malaria chemoprophylaxis regimen^{Reference 14}.

Data collected from deployed military troops also suggest poor adherence to recommended malaria chemoprophylaxis. Of over 1,000 French soldiers assigned to missions in sub-Saharan Africa, only 61% reported taking their chemoprophylaxis^{Reference 15}. A more recent report only 45% compliance with malaria prophylaxis among 575 French soldiers stationed in Ivory Coast^{Reference 16}. This is comparable to the outcome of an anonymous, post-deployment survey of United States Army Rangers returned from Afghanistan, where the self-reported compliance rate was 52% for weekly chemoprophylaxis, 41% for terminal (post-deployment) chemoprophylaxis, 31% for both weekly and terminal chemoprophylaxis. In this group, 82% reported treating uniforms with permethrin, and 29% for the application of insect repellent^{Reference 17}.

Support for established guidelines

In general, guidelines for preventing malaria in long-term travellers or expatriates should be very similar to standard recommendations for the short-term traveller, though cost may limit the use of more expensive drugs such as atovaquone-proguanil. However, given how poorly long-term travellers tend to adhere to malaria chemoprophylaxis, pre-travel advice regarding malaria precautions should also include a description of malaria symptoms and emphasis on the need for early diagnosis and treatment; a discussion of the need to develop a plan for accessing competent medical care in the event of illness; detailed advice regarding PPM (see Chapter 3); the use of standby emergency therapy (self-treatment), if applicable; and the possibility of counterfeit malaria drugs procured locally^{Reference 10}.

Data on the incidence of malaria in long-term travellers are limited; also limited are data on the effectiveness and tolerance of currently recommended regimens. Studies conducted in chloroquine- resistant regions consistently demonstrate that mefloquine is more effective than chloroquine and proguanil and its long-term use and that it is well tolerated^{Reference 5}, ^{Reference 18}, ^{Reference 19}, ^{Reference 20}. Better knowledge about malaria seems to benefit compliance: a preventive malaria program for nonimmune expatriates working in malaria-endemic areas resulted in significant increase in knowledge about malaria and improved practices including greater adherence to chemoprophylaxis^{Reference 19}. Another program that included instruction on Canadian guidelines, PPM and self-treatment with self-administered positive rapid diagnostic tests was instituted for a cohort of expatriates in Ghana, among whom the incidence of malaria ranged from 1/50 to 1/25 per month between 1993 and 1999 (2%–4%). Subsequent surveillance data indicated that the monthly incidence of malaria decreased from 4/1,000 in 2000 to 1.7/1,000 in 2002 (0.4%–0.17%) (unpublished data, K. Gamble).

Insecticide-treated bed nets

CATMAT recommends that all travellers to malaria-endemic regions use insecticide-treated bed nets as part of their PPM (see Chapter 3). For the majority of travellers, conventional insecticide-treated bed nets provide sufficiently long-lasting protection. However, long-term travellers face additional challenges: the insecticide that is in most nets starts to lose its effect after 6 months. Thus, where travel to a malaria-endemic area is frequent and/or is expected to be for 6 months or longer, conventionally treated bed nets are inadequate and long-lasting insecticide- treated nets would be preferable^{Reference 21}. Currently there are no Canadian long-lasting insecticide- treated nets registrations, nor is there a specific policy that permits their sale in Canada for use abroad; in addition, liquid permethrin (an insecticide used to treat bed nets) is not available in Canada. Nevertheless, insecticide-treated bed nets can be obtained from some Canadian travel health clinics and other domestic and international suppliers^{Reference 21}.

Long-term travellers also need to know about seasonal changes in weather that affect malaria risk and loss of effect of the insecticide-impregnating bed nets. This means that the start of rainy seasons requires the renewal of this insecticide in bed nets.

Rapid diagnostic tests

Without adequate training of laboratory staff, the usefulness of rapid diagnostic tests (RDTs) may be no better than that shown in the general travel population^{Reference 22}, ^{Reference 23} (see Chapter 6 for information on malaria diagnosis and RDTs). However, expatriates are often part of a reasonably stable community, which allows for the training of key members on the use of RDTs and the administration of appropriate self-treatment. Caution is warranted, however; there are few data from controlled studies on the use of RDTs in the long-term traveller or expatriate populations. An evaluation of a preventive malaria program for expatriates in malaria-endemic areas, which included RDTs and standby treatment, found that 15% of participants had difficulty performing the RDTs and 22% used standby treatment despite having a negative RDT^{Reference 24}.

Counterfeit drugs

The production, distribution and sale of counterfeit antimalarial, antiretroviral and other medications are widespread throughout many parts of Asia and Africa^{Reference 25}, ^{Reference 26}, ^{Reference 27}. One-third to one-half of artesunate tablets in Southeast Asia have been found to have no active ingredient^{Reference 25}. Many expatriates buy their antimalarial drugs over the counter, and they do not have the ability to evaluate the authenticity of these drugs. Unfortunately, simply encouraging expatriates and long-term travellers to purchase brand names may be insufficient^{Reference 25}, ^{Reference 26}, ^{Reference 27}.

The counterfeit drug problem is especially important for long-term travellers because they are dependent on local pharmacies for renewal of their antimalarial chemoprophylaxis prescriptions and often for standby malaria self-treatment drugs^{Reference 25}, ^{Reference 26}, ^{Reference 27}. Warn all travellers, and especially long-term travellers, expatriates and missionaries, about counterfeit drugs and encourage them to buy a supply of medication in countries where strict quality control measures are in place. If Coartem® (artemether-lumefantrine), which is not yet licensed for distribution in Canada but is recommended by the World Health Organization as first-line treatment for P. falciparum malaria in Africa, is recommended, travellers should buy it in countries where counterfeiting is unlikely (e.g. in Europe or the USA)^{Reference 28}. Although long-term atovaquone-proguanil prophylaxis may be too expensive for most long-term travellers and expatriates, long-term travellers may choose to purchase enough for one or two self-treatment courses to keep in their medical kit^{Reference 29}.

Terminal prophylaxis

Terminal prophylaxis is more of a concern in long-term than in short-term travellers. Expatriates and the military deserve careful consideration (see Chapter 4 “Prevention—Chemoprophylaxis Regimens”).

Table 5.3.1: Evidence-based medicine recommendations

Recommendation	EBM Rating
Guidelines for the prevention of malaria in long-term travellers or expatriates should not deviate considerably from recommendations for short-term travellersReference 30.	B III
Training in the use of RDTs is reasonable for long-term travellersReference 23, Reference 30.	C III
Education about counterfeit antimalarial medications is important for long-term travellers who are more likely to buy drugs in countries without quality controlsReference 25, Reference 26, Reference 27.	C II
Consider primaquine for terminal prophylaxis (see Chapter 8) for military personnel, long-term travellers or expatriates returned from regions with P. vivaxtransmissionReference 17, Reference 28, Reference 30.	A I
Abbreviation: EBM, evidence-based medicine; RDT, rapid diagnostic test. Note: For a description of the categories and quality of evidence of the recommendations, see Appendix IV.

• Previous Page
• Table of Contents
• Next Page