Use of medical chemoprophylaxis and antimosquito precautions in Danish malaria patients and their traveling companions

Thiamine (vitamin B1) as an insect repellent: a scoping review

While the desire for systemic repellents is high, ineffective repellents put one at risk of insect-vectored pathogens. Vitamin B1, or thiamine, has been touted as a systemic insect repellent since 1943, and denounced as an ineffective placebo for just as long. This paper presents a scoping review of 104 relevant case reports, research studies, and review articles to trace the evolution of this idea and identify an evidence-based, scientific consensus. Reports of thiamine's systemic repellency are primarily anecdotal and based on uncontrolled trials and/or used bite symptoms as a proxy for reduced biting. Controlled experiments on insect landing and feeding found no evidence of repellency. Of the 49 relevant review papers, 16 insect bite prevention guidelines, and 4 government documents, none after the 1990s claimed thiamine is a repellent. The findings of this review are that thiamine cannot repel arthropods in any dosage or route of administration. Due to limited available evidence, the possibility that thiamine reduces the subjective symptoms of insect bites cannot currently be ruled out. Unfortunately, many medical professionals and travelers today still believe thiamine may be effective despite the evidence stating otherwise. Continued promotion of debunked repellents on the commercial market poses a serious risk in countries with the endemic, mosquito-vectored disease.

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.

Children with chronic health disorders travelling to the tropics: a prospective observational study

BACKGROUND

The number of trips to the tropics taken by children with chronic health disorders (CHDs) is increasing.

METHODS

All of the children with CHDs who attended two international vaccination centres in France before travelling to the tropics were included in a prospective, exposed/unexposed study. Each child was age-matched with two control children and followed for 1 month after returning from the tropics.

RESULTS

Fifty-six children with CHDs and 107 control children were included. The children's median age was 6 years old (IQR 2-11). Of the study participants, 127/163 (78%) travelled to West Africa, mainly to visit relatives. The median duration of the stay was 42 days (IQR 31-55). The age of the children, the destination and the duration of the trip were similar between the two groups. Sickle cell disease (23/56) and asthma (16/56) were the most common CHDs. Overall, the children with CHDs experienced more clinical events than the control patients did (p<0.05); however, there was no difference when chronic disease exacerbations were excluded (p=0.64) or when only the period abroad was considered (p=0.24). One child with a recent genetic diagnosis of atypical haemolytic uraemic syndrome died from a first disease exacerbation.

CONCLUSIONS

Health problems among children with CHDs travelling abroad are mainly related to chronic disease exacerbations, which mostly occur after the children return. Patients with diseases that require highly specialised care for an exacerbation should avoid travelling to resource-limited tropical countries.

Pharmaceutical care model to assess the medication-related risks of travel

BACKGROUND

People are at greater risk of health problems when travelling and a significant number of travel-related health problems are associated with the effects of travel on pre-existing chronic diseases. Medications play a key role in the management of these conditions. However, there is a notable lack of research evaluating the potential medication-related risks associated with travel.

OBJECTIVE

To apply a systematic pharmaceutical care model developed to evaluate potential pharmaceutical risks (PPRs) and pharmaceutical care issues (PCIs) in travellers.

SETTING

Adult travellers leaving Cairns International Airport, Australia, for an international destination.

METHOD

A cross-sectional survey using semi-structured interviews, including a systematic medication history, followed by the application of a pharmaceutical care model to evaluate each participant for PPRs and PCIs.

MAIN OUTCOME MEASURE

Evaluation of standard clinical and travel-related PPRs and PCIs.

RESULTS

Medications for chronic diseases were being taken by 47.7% of the 218 travellers interviewed. Although 75.2% of participants presented with no PPRs, a total of 274 PCIs were identified across 61.5% of the participants, with an average of 2.04 PCIs per participant. The most prevalent PCIs related to the inadequate precautions taken by some travellers visiting malaria-endemic regions. Although 91 participants recognised that they were travelling to malaria-endemic regions, 65.9% of these participants were not using malarial chemoprophylaxis, and only 16.5% were using chemoprophylaxis that fully complied with standard recommendations. The second most prevalent PCI was the need for 18.8% of participants to be educated about their medications. Other PCIs identified have the potential to increase the risk of acute, travel-related conditions, and complicate the care of travellers, if they inadvertently became unwell while overseas.

CONCLUSION

PPRs and PCIs were not identified in all participants. However, the impact of many of the identified medication-related issues could be substantial to the traveller. This study represents the novel application of a pharmaceutical care model to identify potential PPRs and PCIs in travellers that may not be identified by other pre-travel risk assessment methods.

Summary of recommendations for the prevention of malaria by the Committee to Advise on Tropical Medicine and Travel (CATMAT)

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 risk assessment and prevention of malaria.

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

Used together and correctly, personal protective measures (PPM) and chemoprophylaxis very effectively protect against malaria infection. PPM include protecting accommodation areas from mosquitoes, wearing appropriate clothing, using bed nets pre-treated with insecticide and applying topical insect repellant (containing 20%-30% DEET or 20% icaridin) to exposed skin. Selecting the most appropriate chemoprophylaxis involves assessment of the traveller's itinerary to establish his/her malaria risk profile as well as potential drug resistance issues. Antimalarials available on prescription in Canada include chloroquine (or hydroxychloroquine), atovaquone-proguanil, doxycycline, mefloquine and primaquine.

Rolling back malaria: how well is Europe doing?

Background. The Roll Back Malaria (RBM) initiative has committed itself to halving the worlds's malaria burden by 2010, having adopted five operationally focused 'critical concepts' to guide this task. The focus of RBM's efforts is in the developing world where external support is often required. Malaria was only recently eradicated from Europe, and the continent remains under continual threat of reintroduction. The extent of this threat is examined, and the European response benchmarked against RBM's critical concepts. Methods. The following sources were searched for references using the phrase "imported malaria": RBM, WHO, European Union including Eurosurveillance, and MedLine websites. Links to related articles were followed. Citations were independently assessed by the authors for relevance and inclusion. Results. Only in application of the critical concept "disease surveillance" does the European response seem adequate. Conclusions. Europe should be making greater efforts and considering additional strategies to combat imported malaria.

Determinants of compliance with anti-vectorial protective measures among non-immune travellers during missions to tropical Africa

BACKGROUND

The effectiveness of anti-vectorial malaria protective measures in travellers and expatriates is hampered by incorrect compliance. The objective of the present study was to identify the determinants of compliance with anti-vectorial protective measures (AVPMs) in this population that is particularly at risk because of their lack of immunity.

METHODS

Compliance with wearing long clothing, sleeping under insecticide-impregnated bed nets (IIBNs) and using insect repellent was estimated and analysed by questionnaires administered to 2,205 French military travellers from 20 groups before and after short-term missions (approximately four months) in six tropical African countries (Senegal, Ivory Coast, Chad, Central African Republic, Gabon and Djibouti). For each AVPM, the association of "correct compliance" with individual and collective variables was investigated using random-effect mixed logistic regression models to take into account the clustered design of the study.

RESULTS

The correct compliance rates were 48.6%, 50.6% and 18.5% for wearing long clothing, sleeping under bed nets and using repellents, respectively. Depending on the AVPM, correct compliance was significantly associated with the following factors: country, older than 24 years of age, management responsibilities, the perception of a personal malaria risk greater than that of other travellers, the occurrence of life events, early bedtime (i.e., before midnight), the type of stay (field operation compared to training), the absence of medical history of malaria, the absence of previous travel in malaria-endemic areas and the absence of tobacco consumption.There was no competition between compliance with the different AVPMs or between compliance with any AVPM and malaria chemoprophylaxis.

CONCLUSION

Interventions aimed at improving compliance with AVPMs should target young people without management responsibilities who are scheduled for non-operational activities in countries with high risk of clinical malaria. Weak associations between compliance and history of clinical malaria or variables that pertain to threat perception suggest that cognition-based interventions referencing a "bad experience" with clinical malaria could have only a slight impact on the improvement of compliance. Further studies should focus on the cognitive and behavioural predictors of compliance with AVPMs.

Travellers returning to Sweden with falciparum malaria: Pre-travel advice, behaviour, chemoprophylaxis and diagnostic delay

We have investigated pre-travel advice, behaviour, chemoprophylaxis and diagnostic delay in travellers returning to Sweden with falciparum malaria. Questionnaires were distributed to patients having been notified with falciparum malaria from 1994 to 2001. Of 408 notified patients, 237 (58%) returned the questionnaires; 62% were males and 43% above the age of 45 y. Africa was the travel destination in 90% of the cases, and 27% had travelled to Kenya. 69% had spent more than 1 night in the countryside, and 6% had stayed in modern urban areas only. 40% took an adequate dose of chemoprophylaxis, although this proportion decreased from 55% to 12% during the study period. Nine per cent used both bed nets and mosquito repellents regularly. The median time from onset of symptoms to contact with health care professionals was 2 d, and from that contact to start of malaria treatment the median time was less than 24 h.

Plasmodium falciparum multiple infections, disease severity and host characteristics in malaria affected travellers returning from Africa

BACKGROUND

The pathogenesis of malaria is the result of complex interactions between parasites, host and environment. Several studies have assessed the role of genetic characteristics of Plasmodium falciparum infection in the clinical severity of malaria infection comparing different genotypic determinants in mild and severe cases. The genes encoding the polymorphic merozoite surface proteins 1 (msp-1) and 2 (msp-2) and the dihydrofolate reductase (dhfr) of malaria parasites have been extensively used as markers to investigate the genetic diversity and the population structure of P. falciparum. The aim of this study was to assess the epidemiological, clinical, host- and parasite-related determinant factor of the genetic diversity of P. falciparum infections in travellers returning to Italy.

METHODS

Between 1998 and 2001, we have retrospectively studied 64 inpatients all returning from African malaria-endemic countries. Designation of severe malaria was determined by using the World Health Organization (WHO) definition. P. falciparum infections detected by species-specific PCR were genotyped at the msp-1 and msp-2 loci and clones were determined. PCR and enzyme-digestion methods were used to screen the mutation occurring at codon 108.

RESULTS

Multiple P. falciparum genotypes were detected in 32 patients (50%). The number of genotypes was correlated to different host characteristics. No association was found between allelic number of msp-1 or msp-2 and season of travel, absence of antimalarial prophylaxis, length of stay or blood parasitemia. At multiple analysis adjusted for few confounding variables, two variables showed a significant association with multiplicity of P. falciparum genotypes: male gender (p=0.018) and severity of disease (p=0.044).

CONCLUSION

In our study all but one patients with severe malaria had a infection with a multiplicity of P. falciparum clones. At multivariate analysis the male gender, and the occurrence of severe malaria were significantly more commonly detected in patients affected by imported malaria with multiple clones.

Malaria risk in travelers

Imported malaria has been an increasing problem in several Western countries in the last 2 decades. To calculate the risk factors of age, sex, and travel destination in Swedish travelers, we used data from the routine reporting system for malaria (mixture of patients with and without adequate prophylaxis), a database on travel patterns, and in-flight or visa data on Swedish travelers of 1997 to 2003. The crude risk for travelers varied from 1 per 100,000 travelers to Central America and the Caribbean to 357 per 100,000 in central Africa. Travelers to East Africa had the highest adjusted odds ratio (OR = 341, 95% confidence intervals [CI] 134-886) for being reported with malaria, closely followed by travelers to central Africa and West Africa. Male travelers as well as children <1-6 years of age had a higher risk of being reported with malaria (OR = 1.7, 95% CI 1.3-2.3 and OR = 4.8, 95% CI 1.5-14.8) than women and other age groups.

Antimosquito precautions and medical chemoprophylaxis in French children with malaria

BACKGROUND

France is the European country with the highest number of imported malaria cases (7,500 in 2000). The aim of this prospective study was to evaluate the nature and efficacy of prophylactic measures in children under 15 years of age referred for malaria.

METHODS

Post travel questionnaires were given to the parents of malarial children in the emergency room. The study took place in two university hospitals in Marseilles, southern France, from August to October 2001.

RESULTS

Eighty-eight children under 15 years of age were included in this 3-month period. Most of them had been infected in Comoro archipelago. Almost two-thirds used bed nets, but only 47% did so every night. Sprayed bed nets were used by 23%. Average compliances with cutaneous repellents, bedroom repellents and long-sleeved clothing were 32%, 24% and 26%, respectively. Air conditioners were uncommon. Only 22% of the children used chemoprophylaxis correctly, according to French recommendations. Five percent did not use any chemoprophylaxis, and 61% reported non recommended drug use. Although all the children traveled to chloroquine-resistant areas, chemoprophylaxis with mefloquine was less common than that with chloroquine + proguanil. No child fully complied with French recommendations concerning both anti mosquito measures and chemoprophylaxis.

CONCLUSIONS

Insufficient use of antimalaria precautions by traveling families is associated with the high incidence of pediatric imported malaria in southern France. Travelers' education should be increased to allow the optimization of malaria prophylaxis.

Evaluation of malaria chemoprophylaxis in Bahrain

The Kingdom of Bahrain is an archipelago located in the Arabian Gulf with a population of 650,000. A well-established network of 21 primary health care centers provide free health care for all residents, including citizens and expatriates. Patients requiring special investigation, consultation with specialists or admission are referred to the Salmaniya Medical Complex (SMC), which provides secondary and tertiary care. Malaria is a medical condition referred to SMC for medical care. Advice on appropriate prophylactic antimalarial regimens is a service provided by and limited to a public health advisory body, including the Public Health Directorate in the Ministry of Health, and a mini-clinic known as a vaccination clinic located at one of the 21 primary health centers spread across the country. This clinic is staffed by a trained nurse; it provides services such as vaccination and malaria chemoprophylaxis advice. The recommended prophylactic drugs have to be purchased by the travelers from private pharmacies; they are considered to be over-the-counter (OTC) medications.

Randomized, parallel placebo-controlled trial of primaquine for malaria prophylaxis in Papua, Indonesia

Malaria causes illness or death in unprotected travelers. Primaquine prevents malaria by attacking liver-stage parasites, a property distinguishing it from most chemoprophylactics and obviating 4-week postexposure dosing. A daily adult regimen of 30 mg primaquine prevented malaria caused by Plasmodium falciparum and P. vivax for 20 weeks in 95 of 97 glucose-6-phosphate dehydrogenase (G6PD)-normal Javanese transmigrants in Papua, Indonesia. In comparison, 37 of 149 subjects taking placebo in a parallel trial became parasitemic. The protective efficacy of primaquine against malaria was 93% (95% confidence interval [CI] 71%-98%); against P. falciparum it was 88% (95% CI 48%-97%), and >92% for P. vivax (95% CI >37%-99%). Primaquine was as well tolerated as placebo. Mild methemoglobinemia (mean of 3.4%) returned to normal within 2 weeks. Blood chemistry and hematological parameters revealed no evidence of toxicity. Good safety, tolerance, and efficacy, along with key advantages in dosing requirements, make primaquine an excellent drug for preventing malaria in nonpregnant, G6PD-normal travelers.

Knowledge of malaria, risk perception, and compliance with prophylaxis and personal and environmental preventive measures in travelers exiting Zimbabwe from Harare and Victoria Falls International airport

BACKGROUND

Travel associated malaria is a major health risk for visitors to malaria endemic destinations. To examine the knowledge of malaria prevention, risk perception, current prophylactic behavior, and compliance with chemoprophylaxis and personal and environmental protection measures we conducted a study in a cohort of travelers exiting Zimbabwe from two international airports during a peak malaria transmission period.

METHODS

Data were collected by pretested self-administered questionnaires from 595 adults in the departure lounges of Harare and Victoria Falls International airports. Excluded were children and travelers from the African continent. A multilingual research assistant supervised data collection.

RESULTS

The majority of travelers obtained health advice prior to travel. Patterns of protective behavior and compliance with prophylaxis were inconsistent with a high perception of malaria threat and good knowledge. About 23% of travelers failed to use chemoprophylaxis during their visit. In the group of travelers who used chemoprophylaxis, 18% were noncompliant. Fifteen drug combinations were in use. Full compliance with medication plus use of personal preventive measures always was estimated as 13%. Forgetfulness was the main cause of noncompliance, followed by deliberate omission due to side effects. Of 57 travelers who reported side effects from current medication, over half used mefloquine.

CONCLUSIONS

There is a need to examine how people process personal risk and communications about risk. We must recognize the competition between precautionary measures against malaria and other life demands that are imposed by travel, especially in young long stay travelers and persons visiting primarily for business purposes. Mediating a protective response will also depend on judgments about the effectiveness of the action, strengthening travelers intentions toward adherence, and increasing efficacy perception by individuals and their peers. Conflicts in prophylactic recommendations need to be resolved. As ecotourism develops in Zimbabwe and other malaria regions, stakeholders in this rapidly growing industry must be made aware of the important role they can play in protecting clients from malaria.