Adherence to chemoprophylaxis and Plasmodium falciparum anti-circumsporozoite seroconversion in a prospective cohort study of Dutch short-term travelers

Polish travellers on the move: A study of knowledge of travel health and associated practices among polish travellers abroad

BACKGROUND

Post-pandemic travel has surged, with 1.3 billion journeys recorded worldwide in 2023, reflecting a growing interest in tropical destinations despite the associated health risks. Access to travel health information has improved, yet adherence to preventive measures remains limited due to misinformation, insufficient pre-travel consultations, and concerns about malaria prophylaxis. Based on data from a three-year survey, this study examines the attitudes of Polish travellers to vaccinations, malaria prophylaxis, and COVID-19-related measures.

METHODS

Surveys conducted during travel festivals from 2021 to 2023 targeted adult participants. A questionnaire designed by experts in travel medicine addressed the demographics, travel behaviours, and health-related practices. Statistical analyses, including chi-squared tests and logistic regression, explored the impact of demographic factors on behaviours, using Python for data analysis.

RESULTS

Among 644 participants (mean age 32; 48 % male), 49.5 % reported pre-travel vaccination and 281 intended to use malaria chemoprophylaxis. Gender significantly influenced vaccination status and travel to Africa. The most cited malaria prevention methods were repellents and mosquito nets. Illnesses were reported by 317 participants, with travellers' diarrhoea (185 cases) most common, particularly in Turkey, Egypt, and India. Forty-eight individuals required medical consultations.

CONCLUSIONS

Education and pre-travel counseling enhance adherence to preventive measures, yet many travellers fail to follow recommendations. Malaria remains the most common travel-imported disease in the EU/EEA, with 4856 cases in 2021. The Capability, Opportunity, and Motivation Behavior (COM-B) model highlights the importance of addressing these factors to improve compliance with preventive behaviours.

Travellers' adherence to atovaquone/proguanil malaria chemoprophylaxis after return from endemic areas

BACKGROUND

According to current guidelines, atovaquone/proguanil (AP) malaria chemoprophylaxis is taken once daily during travel, and continued for seven days after return from malaria-endemic areas. However, pharmacokinetic data and studies on drug-sparing AP regimens suggest that AP could possibly be discontinued upon return without loss of protection. Besides being more cost-effective, shorter AP regimens may enhance adherence. We aimed to investigate adherence to the current AP chemoprophylaxis regimen during the seven days post-travel, and travellers' preferences for potential drug-sparing AP regimens.

METHODS

In this cross-sectional study, adult travellers, who were prescribed AP chemoprophylaxis during a pre-travel consultation between 01-12-2022 and 01-12-2023 at the Amsterdam UMC travel clinic, were send a post-travel online questionnaire. The primary outcome was the proportion of travellers non-adherent to AP during the seven days post-travel, defined as missing one tablet or more. Secondary outcomes were non-adherence during travel, reasons for non-adherence, and AP regimen preferences.

RESULTS

The questionnaire was completed by 62 % (382/614) of contacted travellers. Of the participants, 31 % (117/382) reported non-adherence during the seven days post-travel; during stay this was 16 % (58/382). Frequently reported reasons for non-adherence were: forgetfulness, low self-perceived malaria risk, and adverse effects. An alternative AP regimen discontinuing AP upon return was deemed most appealing and easy to adhere by 73 % (276/376) of participants.

CONCLUSIONS

Non-adherence was high during the seven days after return. Travellers preferred an alternative AP chemoprophylaxis regimen, allowing them to discontinue upon return. Future research shall be conducted to investigate whether AP could be discontinued upon return.

Adherence to stand-by emergency treatment and mosquito protection measures in short-term travellers to moderate malaria risk areas

Background

Malaria remains a threat to travellers to (sub)tropical regions. This study assessed adherence to malaria prevention measures among travellers to moderate-risk malaria areas, including the use of standby emergency treatment (SBET), healthcare-seeking behaviour during fever, and mosquito protection measures.

Methods

We analysed data from adult travellers to moderate-risk malaria areas participating in a prospective study (2018-2023) at the Public Health Service of Amsterdam, the Netherlands. Participants maintained a daily diary during travel, recording questions about adherence to mosquito protection measures, symptoms, SBET use, and seeking medical help. In case of fever, participants were instructed to measure their temperature, use SBET if in a remote area, and seek medical help. We used Poisson regression to assess determinants for adherence to mosquito protection measures.

Results

Of 686 recruited travellers, 405 (59 %) completed the diary. Of these travellers 44 % received a pre-travel SBET prescription, although presumably only a small fraction of them actually travelled remotely. None of the 25 travellers who reported fever used the prescribed SBET and five sought medical care. Thirty-five percent of participants used DEET and 5 % used a mosquito net on ≥75 % of the nights with malaria risk. Longer travel duration was associated with lower adherence to DEET use.

Conclusions

Few travellers with fever used SBET or sought medical care, despite their pre-travel advice. To reduce costs and medication spillage, SBET should only be advised to travellers who travel to very remote regions where medical help is inaccessible. Further research should focus on the behavioural concepts underlying these choices.

Malaria Disease and Chemoprophylaxis Usage among Israeli Travelers to Endemic Countries

Prevention of malaria in travelers to endemic countries is one of the complex challenges of travel medicine. Israel has a widespread culture of travel to developing countries, but information regarding malaria prevention is limited so far. Our study, conducted in Sheba Medical Center, Israel, during the years 2008-2018 examined malaria chemoprophylaxis usage and malaria cases in a large group of Israeli travelers returning from endemic countries with any medical complaint. Data were collected regarding travel destinations, conditions, duration of stay, and pretravel consultation. Altogether, 4,708 travelers were included in our study. Travel destinations included Asia (51%), Latin America (31%), and sub-Saharan Africa (SSA) (17%). Median travel duration was 26 days. Only 11.9% reported taking malaria chemoprophylaxis. Of the travelers to SSA, 41.3% took prophylaxis as opposed to only 6% outside of Africa. During the study years, 136 cases of malaria were diagnosed; among them, 82 (60%) were infected with Plasmodium falciparum, of whom all but two were from SSA and none adhered to prophylaxis. Malaria chemoprophylaxis usage was found to be negligible in travel to many countries still considered endemic. Higher prophylaxis usage was found among travelers to SSA, but numbers are still lower than recommended. The low number of malaria cases seen in destinations outside SSA, as documented in our cohort, is likely to represent travel to low risk areas and not high prophylaxis usage. We urge re-evaluation of current CDC and Israeli guidelines which still recommend using chemoprophylaxis in many low-risk countries, as focus on high-risk countries may increase adherence.

Adherence to recommendations at a Canadian tertiary care Family Travel Clinic - A single centre analysis

BACKGROUND

Infectious and non-infectious risks associated with international travel can be reduced with adherence to pre-travel advice from practitioners trained in travel medicine.

METHODS

A prospective cohort study was conducted in a tertiary care children's hospital to assess adherence to malaria chemoprophylaxis, safe water and food consumption, mosquito bite protection, motor vehicle safety and travel vaccines using structured questionnaires. High risk groups assessed included child travelers and those visiting friends and relatives (VFRs).

RESULTS

In total, 290 participants (133 children and 157 adults) were enrolled and completed at least one study questionnaire. In general, with the exception of vaccines, adherence to recommendations was sub-optimal. Among children and adults, adherence to malaria prophylaxis recommendations was lower in VFRs than in non-VFRs. The proportion of children VFRs (cVFRs) and adult VFRs (aVFRs) who adhered to the following recommendations were malaria chemoprophylaxis (47%, 33%), safe water (71%, 74%) and food recommendations (18%, 6%), insect bite avoidance (21%, 12%), and motor vehicle safety (13%, 11%) respectively. Adherence to recommended vaccines uptake was greater than 90% in all groups.

CONCLUSION

With the exception of vaccine uptake, sub-optimal adherence levels to travel recommendations was identified in all groups, and in particular VFRs, highlighting the need for proactive discussions around barriers to adherence.

A systematic review of factors affecting adherence to malaria chemoprophylaxis amongst travellers from non-endemic countries

Background

The aim of this systematic review was to identify predictors of actual or intended adherence with malaria chemoprophylaxis amongst travellers from non-endemic countries visiting endemic countries.

Methods

A systematic review of the literature was conducted using MEDLINE, Embase, PsycINFO and Global Health databases for studies published up to April 2019. Studies were included if they assessed reasons for adherence among people travelling from a country where malaria was not endemic to a country where it was.

Results

Thirty-two studies were included. Predictors of adherence were categorized as relating to either the nature of the travel or the traveller themselves. The three main predictors associated with nature of travel included: destination (e.g. country visited, urban vs rural areas), length of travel and type of travel (e.g. package vs backpacking holiday). The four main traveller-associated predictors were: age, reason for travel (e.g. business, leisure or visiting friends and relatives), perceived risk of catching malaria and experienced or expected medication effects.

Conclusions

In order to improve adherence, clinicians should focus on travellers who are least likely to exhibit adherent behaviour. This includes travellers visiting destinations known to have lower adherence figures (such as rural areas), backpackers, business travellers, younger travellers and those travelling for longer periods of time. They should also check to ensure travellers’ perceptions of the risks of malaria are realistic. Where appropriate, misperceptions (such as believing that curing malaria is easier than taking prophylaxis or that travellers visiting relatives have some level of innate immunity) should be corrected. All travellers should be informed of the potential side-effects of medication and given guidance on why it is nonetheless beneficial to continue to take prophylaxis. Further research is required to test interventions to improve adherence.

Compliance with Primary Malaria Chemoprophylaxis: Is Weekly Prophylaxis Better Than Daily Prophylaxis?

BACKGROUND

Chemoprophylaxis is an effective tool for individuals to minimize their risk of contracting malaria and serves an important public health role in preventing imported malaria. Yet, it is only effective if the traveller is fully compliant with the prescribed regimen. For many destinations, a choice of prophylactic agents is available, so historical compliance data can be helpful for both physicians and travellers to make an informed decision.

METHODS

We analyzed the historical self-reported compliance data for six chemoprophylactic agents currently recommended by CDC for primary malaria chemoprophylaxis by searching PubMed, Embase, CINAHL, Web of Science, and Scopus for observational studies reporting on travelers within the last 25 years. The quality of data was graded as "good" or "poor" using the NIH quality assessment tool for cohort and cross-sectional studies. Cumulative compliance data were compiled for all studies (gross compliance) and the subgroup of studies with "good" quality evidence (refined compliance). Subgroup analyses were performed for weekly vs daily administered regimens, between military and civilian travelers, and across each prophylactic agent.

RESULTS

Twenty-four eligible studies assessed compliance for mefloquine (n=20), atovaquone-proguanil (n=11), doxycycline (n=13), and chloroquine (n=3). No studies were found for primaquine or tafenoquine. Both gross and refined compliance were significantly better for weekly regimens than daily regimens (P<0.0001). Stopping chemoprophylaxis due to adverse events was significantly more for doxycycline (P<0.0001) compared to other drugs. Compliance was significantly worse in military travelers, but they were also more likely to be prescribed doxycycline.

CONCLUSION

Malaria chemoprophylaxis for a traveler should depend on prevailing resistance patterns at destination, current national guidelines, and patient preferences. However, when there is a choice, historical compliance data are useful to select a regimen that the traveler is more likely to comply with.

Non-adherence to malaria prophylaxis: The influence of travel-related and psychosocial factors

BACKGROUND

The effectiveness of malaria chemoprophylaxis is limited by a lack of compliance in travellers. This study assesses the demographic, travel-related, and psychosocial determinants of non-compliance with chemoprophylaxis.

METHODS

715 adults, who received a pre-travel malaria prophylaxis prescription, were invited to complete a post-travel digital questionnaire on non-compliance, demographics, travel-related and psychosocial variables.

RESULTS

330 travellers (53% response) reported 32% non-compliance with malaria chemoprophylaxis. Logistic regression analyses revealed that 3/11 assessed psychosocial variables uniquely predicted non-compliance: 'negative attitude towards chemoprophylaxis' (β=0.694, OR 2.0, p<0.01), 'low perceived severity of malaria' (β=0.277, p=0.04) and 'fatigue during travel' (β=2.225, OR 9.3, p<0.01). Furthermore, the age and education of the traveller were uniquely predictive of non-compliance (β=-0.023 (p=0.02) and β=0.684 (p=0.04)). None of the travel-related variables predicted non-compliance.

CONCLUSIONS

About one-third of the travellers in our study were non-compliant with malaria prophylaxis, especially young travellers and highly educated travellers. Fatigue during travel seems to lead to non-compliance. Further research should focus on addressing the psychosocial factors in pre-travel consultation, since these appear to be better predictors for intention to comply than travel-related variables.

Malaria prevention in the older traveller: a systematic review

Older travellers are at higher risk of malaria-related morbidity and mortality compared with younger people. Yet, prevention of malaria in this specific group of travellers is a long-standing issue in travel medicine. The aim of this research was to synthetize the existing evidence about this important topic, highlighting older travellers' attitudes and practises toward malaria prevention. Searches were performed on PubMed, Embase, EuropePMC, Web of Science, WHOLIS and LILACS databases for relevant studies reporting malaria prevention measures in older travellers. To measure malaria prevention in the older traveller population, the main information outcomes were obtained from the ABCD framework that included travellers' 'Awareness' towards pre-travel health advice, their utilisation of 'Bite-prevention measures' and adherence to 'Chemoprophylaxis'. Data on 'Diagnosis'-related outcomes were excluded for not being measures of malaria prevention. Three evaluators independently selected studies, extracted data and assessed the quality of the included articles. The research protocol was registered with PROSPERO (protocol number CRD42019124202). Out of the 899 titles and abstracts screened, 13 articles were included in this review synthesis. These studies included a wide range of interventions for malaria prevention: no relevant differences in pre-travel healthcare attendance were found depending on age; older travellers were found to be less likely to comply with bite-prevention measures; three high-quality studies reported that adherence to chemoprophylaxis significantly increased with age, while three studies did not find age-related differences in travellers' adherence. Overall, prevention of malaria in the older traveller has received limited attention from the scientific community. Older travellers seem to be less likely to comply with bite-prevention measures, but there was high heterogeneity across the reports. This population group demands particular attention and tailored health advice before travelling to malaria endemic areas. More research is required on how to improve malaria prevention in the older traveller.

Adherence to malaria prophylaxis among travelers from a middle-income country

INTRODUCTION

Malaria is the main cause of death by infection among travelers and is preventable through a combination of chemoprophylaxis and personal protective measures.

METHODS

Travelers were interviewed by phone 28-90 days after returning, to assess adherence to pre-travel advice for malaria prevention.

RESULTS

A total 57 travelers were included. Adherence to chemoprophylaxis was significantly higher among participants prescribed mefloquine (n=18; 75%) than doxycycline (n=14; 45%). Adherence to mosquito repellent and bed net use was 65% and 67%, respectively.

CONCLUSIONS

Adherence to malaria prophylaxis was lower than expected. Further studies testing innovative approaches to motivate travelers' compliance are required.

Methods for Measuring Multiple Medication Adherence: A Systematic Review-Report of the ISPOR Medication Adherence and Persistence Special Interest Group

BACKGROUND

A broad literature base exists for measuring medication adherence to monotherapeutic regimens, but publications are less extensive for measuring adherence to multiple medications.

OBJECTIVES

To identify and characterize the multiple medication adherence (MMA) methods used in the literature.

METHODS

A literature search was conducted using PubMed, PsycINFO, the International Pharmaceutical Abstracts, the Cumulative Index to Nursing and Allied Health Literature and the Cochrane Library databases on methods used to measure MMA published between January 1973 and May 2015. A two-step screening process was used; all abstracts were screened by pairs of researchers independently, followed by a full-text review identifying the method for calculating MMA. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to conduct this systematic review. For studies that met the eligibility criteria, general study and adherence-specific characteristics and the number and type of MMA measurement methods were summarized.

RESULTS

The 147 studies that were included originated from 32 countries, in 13 disease states. Of these studies, 26 used proportion of days covered, 23 used medication possession ratio, and 72 used self-reported questionnaires (e.g., the Morisky Scale) to assess MMA. About 50% of the studies included more than one method for measuring MMA, and different variations of medication possession ratio and proportion of days covered were used for measuring MMA.

CONCLUSIONS

There appears to be no standardized method to measure MMA. With an increasing prevalence of polypharmacy, more efforts should be directed toward constructing robust measures suitable to evaluate adherence to complex regimens. Future research to understand the validity and reliability of MMA measures and their effects on objective clinical outcomes is also needed.

Mefloquine for preventing malaria during travel to endemic areas

BACKGROUND

Mefloquine is one of four antimalarial agents commonly recommended for preventing malaria in travellers to malaria-endemic areas. Despite its high efficacy, there is controversy about its psychological side effects.

OBJECTIVES

To summarize the efficacy and safety of mefloquine used as prophylaxis for malaria in travellers.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published on the Cochrane Library; MEDLINE; Embase (OVID); TOXLINE (https://toxnet.nlm.nih.gov/newtoxnet/toxline.htm); and LILACS. We also searched the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP; http://www.who.int/ictrp/en/) and ClinicalTrials.gov (https://clinicaltrials.gov/ct2/home) for trials in progress, using 'mefloquine', 'Lariam', and 'malaria' as search terms. The search date was 22 June 2017.

SELECTION CRITERIA

We included randomized controlled trials (for efficacy and safety) and non-randomized cohort studies (for safety). We compared prophylactic mefloquine with placebo, no treatment, or an alternative recommended antimalarial agent. Our study populations included all adults and children, including pregnant women.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the eligibility and risk of bias of trials, extracted and analysed data. We compared dichotomous outcomes using risk ratios (RR) with 95% confidence intervals (CI). Prespecified adverse outcomes are included in 'Summary of findings' tables, with the best available estimate of the absolute frequency of each outcome in short-term international travellers. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 20 RCTs (11,470 participants); 35 cohort studies (198,493 participants); and four large retrospective analyses of health records (800,652 participants). Nine RCTs explicitly excluded participants with a psychiatric history, and 25 cohort studies stated that the choice of antimalarial agent was based on medical history and personal preference. Most RCTs and cohort studies collected data on self-reported or clinician-assessed symptoms, rather than formal medical diagnoses. Mefloquine efficacyOf 12 trials comparing mefloquine and placebo, none were performed in short-term international travellers, and most populations had a degree of immunity to malaria. The percentage of people developing a malaria episode in the control arm varied from 1% to 82% (median 22%) and 0% to 13% in the mefloquine group (median 1%).In four RCTs that directly compared mefloquine, atovaquone-proguanil and doxycycline in non-immune, short-term international travellers, only one clinical case of malaria occurred (4 trials, 1822 participants). Mefloquine safety versus atovaquone-proguanil Participants receiving mefloquine were more likely to discontinue their medication due to adverse effects than atovaquone-proguanil users (RR 2.86, 95% CI 1.53 to 5.31; 3 RCTs, 1438 participants; high-certainty evidence). There were few serious adverse effects reported with mefloquine (15/2651 travellers) and none with atovaquone-proguanil (940 travellers).One RCT and six cohort studies reported on our prespecified adverse effects. In the RCT with short-term travellers, mefloquine users were more likely to report abnormal dreams (RR 2.04, 95% CI 1.37 to 3.04, moderate-certainty evidence), insomnia (RR 4.42, 95% CI 2.56 to 7.64, moderate-certainty evidence), anxiety (RR 6.12, 95% CI 1.82 to 20.66, moderate-certainty evidence), and depressed mood during travel (RR 5.78, 95% CI 1.71 to 19.61, moderate-certainty evidence). The cohort studies in longer-term travellers were consistent with this finding but most had larger effect sizes. Mefloquine users were also more likely to report nausea (high-certainty evidence) and dizziness (high-certainty evidence).Based on the available evidence, our best estimates of absolute effect sizes for mefloquine versus atovaquone-proguanil are 6% versus 2% for discontinuation of the drug, 13% versus 3% for insomnia, 14% versus 7% for abnormal dreams, 6% versus 1% for anxiety, and 6% versus 1% for depressed mood. Mefloquine safety versus doxycyclineNo difference was found in numbers of serious adverse effects with mefloquine and doxycycline (low-certainty evidence) or numbers of discontinuations due to adverse effects (RR 1.08, 95% CI 0.41 to 2.87; 4 RCTs, 763 participants; low-certainty evidence).Six cohort studies in longer-term occupational travellers reported our prespecified adverse effects; one RCT in military personnel and one cohort study in short-term travellers reported adverse events. Mefloquine users were more likely to report abnormal dreams (RR 10.49, 95% CI 3.79 to 29.10; 4 cohort studies, 2588 participants, very low-certainty evidence), insomnia (RR 4.14, 95% CI 1.19 to 14.44; 4 cohort studies, 3212 participants, very low-certainty evidence), anxiety (RR 18.04, 95% CI 9.32 to 34.93; 3 cohort studies, 2559 participants, very low-certainty evidence), and depressed mood (RR 11.43, 95% CI 5.21 to 25.07; 2 cohort studies, 2445 participants, very low-certainty evidence). The findings of the single cohort study reporting adverse events in short-term international travellers were consistent with this finding but the single RCT in military personnel did not demonstrate a difference between groups in frequencies of abnormal dreams or insomnia.Mefloquine users were less likely to report dyspepsia (RR 0.26, 95% CI 0.09 to 0.74; 5 cohort studies, 5104 participants, low certainty-evidence), photosensitivity (RR 0.08, 95% CI 0.05 to 0.11; 2 cohort studies, 1875 participants, very low-certainty evidence), vomiting (RR 0.18, 95% CI 0.12 to 0.27; 4 cohort studies, 5071 participants, very low-certainty evidence), and vaginal thrush (RR 0.10, 95% CI 0.06 to 0.16; 1 cohort study, 1761 participants, very low-certainty evidence).Based on the available evidence, our best estimates of absolute effect for mefloquine versus doxycyline were: 2% versus 2% for discontinuation, 12% versus 3% for insomnia, 31% versus 3% for abnormal dreams, 18% versus 1% for anxiety, 11% versus 1% for depressed mood, 4% versus 14% for dyspepsia, 2% versus 19% for photosensitivity, 1% versus 5% for vomiting, and 2% versus 16% for vaginal thrush.Additional analyses, including comparisons of mefloquine with chloroquine, added no new information. Subgroup analysis by study design, duration of travel, and military versus non-military participants, provided no conclusive findings.

AUTHORS' CONCLUSIONS

The absolute risk of malaria during short-term travel appears low with all three established antimalarial agents (mefloquine, doxycycline, and atovaquone-proguanil).The choice of antimalarial agent depends on how individual travellers assess the importance of specific adverse effects, pill burden, and cost. Some travellers will prefer mefloquine for its once-weekly regimen, but this should be balanced against the increased frequency of abnormal dreams, anxiety, insomnia, and depressed mood.

Response to fever and utilization of standby emergency treatment (SBET) for malaria in travellers to Southeast Asia: a questionnaire-based cohort study

Background

Guidelines in several European countries recommend standby emergency treatment (SBET) for travellers to regions with low or medium malaria transmission instead of continuous chemoprophylaxis: travellers are advised to seek medical assistance within 24 h in case of fever and to self-administer SBET only if they are not able to consult a doctor within the time period specified. Data on healthcare-seeking behaviour of febrile travellers and utilization of SBET is however scarce as only two studies were performed in the mid-1990s. Since tourism is constantly increasing and malaria epidemiology has dramatically changed in the meantime more knowledge is urgently needed.

Methods

Some 876 travellers to destinations in South and Southeast Asia with low or medium malaria transmission were recruited in the travel clinic of the University Medical Center Hamburg-Eppendorf. Demographic and travel-related data were collected by using questionnaires. Pre-travel advice was carried out and SBET was prescribed in accordance to national guidelines. Post-travel phone interviews were performed to assess health incidents during travel and individual responses of travellers to febrile illness.

Results

Out of 714 patients who were monitored, 130 (18%) reported onset of fever during travel or 14 days after return. Of those travellers who reported fever, 100 (80%) carried SBET during travel. The vast majority of 79 (79%) febrile travellers who carried SBET did not seek medical assistance. Overall, 14 (14%) febrile patients who carried SBET and six (20%) patients who did not carry SBET took the correct measure (doctor visit or timely SBET administration) as a response to febrile illness, respectively. Only two travellers self-administered SBET, but both of them applied the wrong regimen.

Conclusions

In view of declining malaria transmission and improving medical infrastructure in most countries of Southeast Asia and obvious obstacles concerning SBET as shown in this study the current strategy should be re-evaluated. Pre-travel advice concerning malaria in SEA should focus on appropriate mosquito bite protection and clearly emphasize the need to see a doctor within 24 h after onset of fever.

Immune activation and induction of memory: lessons learned from controlled human malaria infection with Plasmodium falciparum

Controlled human malaria infections (CHMIs) are a powerful tool to assess the efficacy of drugs and/or vaccine candidates, but also to study anti-malarial immune responses at well-defined time points after infection. In this review, we discuss the insights that CHMI trials have provided into early immune activation and regulation during acute infection, and the capacity to induce and maintain immunological memory. Importantly, these studies show that a single infection is sufficient to induce long-lasting parasite-specific T- and B-cell memory responses, and suggest that blood-stage induced regulatory responses can limit inflammation both in ongoing and potentially future infections. As future perspective of investigation in CHMIs, we discuss the role of innate cell subsets, the interplay between innate and adaptive immune activation and the potential modulation of these responses after natural pre-exposure.

Malaria Prevention Strategies: Adherence Among Boston Area Travelers Visiting Malaria-Endemic Countries

We conducted a prospective cohort study to assess adherence to malaria chemoprophylaxis, reasons for nonadherence, and use of other personal protective measures against malaria. We included adults traveling to malaria-endemic countries who were prescribed malaria chemoprophylaxis during a pre-travel consultation at three travel clinics in the Boston area and who completed three or more surveys: pre-travel, at least one weekly during travel, and post-travel (2-4 weeks after return). Of 370 participants, 335 (91%) took malaria chemoprophylaxis at least once and reported any missed doses; 265 (79%) reported completing all doses during travel. Adherence was not affected by weekly versus daily chemoprophylaxis, travel purpose, or duration of travel. Reasons for nonadherence included forgetfulness, side effects, and not seeing mosquitoes. Main reasons for declining to take prescribed chemoprophylaxis were peer advice, low perceived risk, and not seeing mosquitoes. Of 368 travelers, 79% used insect repellent, 46% used a bed net, and 61% slept in air conditioning at least once. Because travelers may be persuaded to stop taking medication by peer pressure, not seeing mosquitoes, and adverse reactions to medications, clinicians should be prepared to address these barriers and to empower travelers with strategies to manage common side effects of antimalarial medications.