Malaria Chemoprophylaxis in German Tourists: A Prospective Study on Compliance and Adverse Reactions

Chloroquine (antimalaria medication with anti SARS-CoV activity) solubility in supercritical carbon dioxide

Unfortunately, malaria still remains a major problem in tropical areas, and it takes thousands of lives each year and causes millions of infected cases. Besides, on December 2019, a new virus known as coronavirus appeared, that its rapid prevalence caused the World Health Organization (WHO) to consider it a pandemic. As a potential drug for controlling or treating these two undesired diseases at the cellular level, chloroquine and its derivatives are being investigated, although they possess side effects, which must be reduced for effective and safe treatments. With respect to the importance of this medicine, the current research aimed to calculate the solubility of chloroquine in supercritical carbon dioxide, and evaluated effect of pressure and temperature on the solubility. The pressure varied between 120 and 400 bar, and temperatures between 308 and 338 K were set for the measurements. The experimental results revealed that the solubility of chloroquine lies between 1.64 × 10^-5 to 8.92 × 10^-4 (mole fraction) with different functionality to temperature and pressure. Although the solubility was indicated to be strong function of pressure and temperature, the effect of temperature was more profound and complicated. A crossover pressure point was found in the solubility measurements, which indicated similar behaviour to an inflection point. For the pressures higher than the crossover point, the temperature indicated direct effect on the solubility of chloroquine. On the other hand, for pressures less than the crossover point, temperature enhancement led to a reduction in the solubility of chloroquine. Moreover, the obtained solubility results were correlated via semi-empirical density-based thermodynamic correlations. Five correlations were studied including: Kumar & Johnston, Mendez-Santiago-Teja, Chrastil, Bartle et al., and Garlapati & Madras. The best performance was obtained for Mendez-Santiago-Teja's correlation in terms of average absolute relative deviation percent (12.0%), while the other examined models showed almost the same performance for prediction of chloroquine solubility.

COVID-19 prevention and treatment: A critical analysis of chloroquine and hydroxychloroquine clinical pharmacology

Nicholas White and coauthors discuss chloroquine and hydroxychloroquine pharmacology in the context of possible treatment of SARS-CoV-2 infection.

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 Chemoprophylaxis and Self-Reported Impact on Ability to Work: Mefloquine Versus Doxycycline

BACKGROUND

It is well known that both mefloquine and doxycycline are commonly associated with adverse effects when taken for malaria chemoprophylaxis. However, the relative impact of these on travelers' ability to work is not so well understood. The aim of this study was to identify which drug has a lesser impact on the ability to work as measured by self-reported severity of adverse effects via a questionnaire.

METHODS

This was a questionnaire-based two-arm cohort study. Participants were soldiers selected from 10 consecutive units training in Kenya during 2012 and 2013. The exposure was either doxycycline or mefloquine and the main outcome measure was impact upon ability to work. Each cohort was advised to take doxycycline or mefloquine with exceptions at the individual level where medically or occupationally advised.

RESULTS

Significantly more (p < 0.0001) doxycycline users reported that one or more adverse effects had interfered with their ability to do their job than mefloquine users. Of the 867 mefloquine users, who reported on the impact of adverse effects, 109 (12.6%) reported that one or more adverse effects had impacted upon their ability to do their job, compared to 152 (22.2%) of the 685 doxycycline users who had reported on the impact of any adverse effects. Doxycycline symptoms were predominantly gastrointestinal and dermatological, whereas mefloquine symptoms were neuropsychiatric.

CONCLUSIONS

Self-reported symptoms were common in those that responded and, while the true background rate of adverse effects (off any medication) is unknown, doxycycline had a significantly increased rate compared with mefloquine and was associated with a greater occupational impact. Therefore, this study supports the view that, for organizations which provide malaria chemoprophylaxis to employees free of charge, mefloquine should be the first-choice antimalarial drug where the only alternative is doxycycline.

Recommendations for malaria prevention in moderate to low risk areas: travellers' choice and risk perception

Background

The considerable malaria decline in several countries challenges the strategy of chemoprophylaxis for travellers visiting moderate- to low-risk areas. An international consensus on the best strategy is lacking. It is essential to include travellers’ opinions in the decision process. The preference of travellers regarding malaria prevention for moderate- to low-risk areas, related to their risk perception, as well as the reasons for their choices were investigated.

Methods

Prior to pre-travel consultation in the Travel Clinic, a self-administered questionnaire was given to travellers visiting moderate- to low-risk malaria areas. Four preventive options were proposed to the traveller, i.e., bite prevention only, chemoprophylaxis, stand-by emergency treatment alone, and stand-by emergency treatment with rapid diagnostic test. The information was accompanied by a risk scale for incidence of malaria, anti-malarial adverse drug reactions and other travel-related risks, inspired by Paling palettes from the Risk Communication Institute.

Results

A total of 391 travellers were included from December 2012 to December 2013. Fifty-nine (15%) opted for chemoprophylaxis, 116 (30%) for stand-by emergency treatment, 112 (29%) for stand-by emergency treatment with rapid diagnostic test, 100 (26%) for bite prevention only, and four (1%) for other choices. Travellers choosing chemoprophylaxis justified their choice for security reasons (42%), better preventive action (29%), higher efficacy (15%) and easiness (15%). The reasons for choosing stand-by treatment or bite prevention only were less medication consumed (29%), less adverse drug reactions (23%) and lower price (9%). Those who chose chemoprophylaxis were more likely to have used it in the past (OR = 3.0 (CI 1.7-5.44)), but were not different in terms of demographic, travel characteristics or risk behaviour.

Conclusions

When travelling to moderate- to low-risk malaria areas, 85% of interviewees chose not to take chemoprophylaxis as malaria prevention, although most guidelines recommend it. They had coherent reasons for their choice. New recommendations should include shared decision-making to take into account travellers’ preferences.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-0654-y) contains supplementary material, which is available to authorized users.

Intent-to-adhere and adherence to malaria prevention recommendations in two travel clinics

Malaria infects 30,000 travelers annually worldwide. At greatest risk are those who travel for long duration. Prevention of malaria includes chemoprophylaxis. This prospective study on 121 travelers who visited two travel clinics shows that adherence to prophylactic treatment was low, especially in long duration trips, and that adherence rate could be predicted by the much more available intent-to-adhere rate.

Mosquito bite-avoidance attitudes and behaviors in travelers at risk of malaria

INTRODUCTION

Mosquito bite prevention is an important strategy to reduce the risk of contracting malaria and advice on the methods available should be offered in pre-travel consultations. This study examines the attitudes of a cohort of UK travelers to the various bite-avoidance strategies and the extent to which they are practiced when visiting malaria-endemic areas.

METHOD

This was a retrospective cohort study of UK travelers above 18 years of age returning from malaria-endemic areas. Those who agreed to participate were emailed a Web-based questionnaire on their return to the UK. The questionnaire consisted of items relating to attitudes to bite-avoidance measures and malaria and the use of bite-avoidance measures while away.

RESULTS

One hundred and thirty-two travelers completed the questionnaire representing a 51% response rate. Frequent use of repellents (69%) was higher than covering the arms (49%) and legs (56%), or using insecticide vaporizers (16%), sprays (24%), and bed nets (32%). Those under the age of 30 tended to use bite avoidance less frequently. Gender, purpose, and duration of travel were also found to influence the use of particular measures. A reliable 17-point attitude to the bite-avoidance questionnaire (Cronbach's alpha = 0.70) was constructed and a subscale score indicated that attitudes influenced the use of repellents.

CONCLUSION

The use of measures to avoid mosquito bites on retiring and covering arms and legs needs to be further emphasized to travelers. The attitude scales described could be a useful tool in practice and research into this area.

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

Background

We conducted a prospective study in a cohort of short-term travelers assessing the incidence rate of anti-circumsporozoite seroconversion, adherence to chemoprophylaxis, symptoms of malaria during travel, and malaria treatment abroad.

Methods

Adults were recruited from the travel clinic of the Public Health Service Amsterdam. They kept a structured daily travel diary and donated blood samples before and after travel. Blood samples were serologically tested for the presence of Plasmodium falciparum anti-circumsporozoite antibodies.

Results

Overall, the incidence rate (IR) of anti-circumsporozoite seroconversion was 0.8 per 100 person-months. Of 945 travelers, 620 (66%) visited high-endemic areas and were advised about both chemoprophylaxis and preventive measures against mosquito bites. Most subjects (520/620 = 84%) took at least 75% of recommended prophylaxis during travel. Travel to Africa, use of mefloquine, travel duration of 14–29 days in endemic areas, and concurrent use of DEET (N,N-diethyl-meta-toluamide) were associated with good adherence practices. Four travelers without fever seroconverted, becoming anti-circumsporozoite antibody-positive. All four had been adherent to chemoprophylaxis; two visited Africa, one Suriname, one India. Ten subjects with fever were tested for malaria while abroad and of these, three received treatment. All three were adherent to chemoprophylaxis and tested negative for anti-circumsporozoite antibodies.

Conclusion

Travel to Africa, using mefloquine, travel duration of 14–29 days in endemic areas, and use of DEET were associated with good adherence to chemoprophylaxis. The combination of chemoprophylaxis and other preventive measures were sufficient to protect seroconverting travelers from clinical malaria. Travelers who were treated for malaria abroad did not seroconvert.

Choice of and adherence to prophylactic antimalarials

BACKGROUND

There were 1,370 cases of imported malaria and six fatalities in the UK in 2008, the majority of which were due to chloroquine-resistant Plasmodium falciparum. Poor adherence to prescribed regimens is known to be an important factor in these cases.

METHOD

An observational study utilizing questionnaires both pre- and post-travel was conducted to assess the adherence behavior of UK travelers undertaking trips of less than 28 days duration, who were prescribed one of three antimalarials recommended to prevent P falciparum malaria (atovaquone plus proguanil, doxycycline, or mefloquine) in travel clinics in England and Scotland. The primary objectives of the study were to assess travelers' perceptions of, and self-reported adherence to antimalarial medication. A secondary objective was to examine the reasons for the choice of antimalarial therapy from the perspective of prescriber and traveler.

RESULTS

For the primary end point of self-reported adherence specified as the proportion of antimalarial tablets prescribed that were actually taken, statistically significantly higher adherence overall and post-travel was seen with atovaquone plus proguanil compared with doxycycline. It was not possible to calculate the statistical significance of comparisons with mefloquine, but adherence to mefloquine appeared similar to or better than doxycycline and similar to atovaquone plus proguanil for categorical adherence. Effectiveness, side effects, previous experience of antimalarials, and dosing convenience were the main determinants of both travelers and practitioner's choice of antimalarial. The practitioner's recommendation was highly important for 63% of travelers.

CONCLUSION

A shorter post-travel regimen has a significant impact on adherence to antimalarial prophylaxis. A reassessment of the risk by travelers on returning home may be a major contributor to this poor adherence.

Biowaiver monographs for immediate release solid oral dosage forms: mefloquine hydrochloride

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release solid oral dosage forms containing mefloquine hydrochloride as the only active pharmaceutical ingredient (API) are reviewed. The solubility and permeability data of mefloquine hydrochloride as well as its therapeutic use and therapeutic index, its pharmacokinetic properties, data related to the possibility of excipient interactions and reported BE/bioavailability studies were taken into consideration. Mefloquine hydrochloride is not a highly soluble API. Since no data on permeability are available, it cannot be classified according to the Biopharmaceutics Classification System with certainty. Additionally, several studies in the literature failed to demonstrate BE of existing products. For these reasons, the biowaiver cannot be justified for the approval of new multisource drug products containing mefloquine hydrochloride. However, scale-up and postapproval changes (HHS-FDA SUPAC) levels 1 and 2 and most EU type I variations may be approvable without in vivo BE, using the dissolution tests described in these regulatory documents.

WITHDRAWN: Mefloquine for preventing malaria in non-immune adult travellers

BACKGROUND

Mefloquine is commonly prescribed to prevent malaria in travellers, and has replaced other drugs because Plasmodium falciparum is commonly resistant to them. However, mefloquine may be associated with neuropsychiatric harmful effects.

OBJECTIVES

To assess the effects of mefloquine in adult travellers compared to other regimens in relation to episodes of malaria, withdrawal from prophylaxis, and adverse events.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group specialized trials register (September 2002), The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2002), MEDLINE (1966 to September 2002), EMBASE (1980 to September 2002), LILACS (September 2002), Science Citation Index (1981 to September 2002), and bibliographies in retrieved papers and standard textbooks. We contacted researchers in the subject of malaria chemoprophylaxis, and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing mefloquine with other standard prophylaxis or placebo in non-immune adult travellers, and in non-travelling volunteers. For adverse events, any published case reports were collected.

DATA COLLECTION AND ANALYSIS

We independently assessed trial quality and extracted data. Adverse events from observational studies were categorised by the study type. We also contacted study authors.

MAIN RESULTS

We included 10 trials involving 2750 non-immune adult participants. Five of these were field trials, and of these all were in mainly male soldiers. One trial comparing mefloquine with placebo showed mefloquine prevented malaria episodes in an area of drug resistance (Peto odds ratio 0.04, 95% confidence interval 0.02 to 0.08). Withdrawals in the mefloquine group were consistently higher in four placebo controlled trials (odds ratio 3.56, 95% confidence interval 1.67 to 7.60). In five trials comparing mefloquine with other chemoprophylaxis, no difference in tolerability was detected. We found 516 published case reports of mefloquine adverse effects. 63 per cent of these published reports involved tourists and business travellers. There were four fatalities attributed to mefloquine.

AUTHORS' CONCLUSIONS

Mefloquine prevents malaria, but has adverse effects that limit its acceptability . There is evidence from non-randomised studies that mefloquine has potentially harmful effects in tourists and business travellers, and its use needs to be carefully balanced against this. Trials of comparative effects of antimalarial prophylaxis should include episodes of malaria and withdrawal from prophylaxis as outcomes.

Problem pathogens: prevention of malaria in travellers

Human infection with Plasmodium spp leading to clinical episodes of malaria probably began very early in the history of humankind and has persistently inflicted disease among human populations. Malaria is currently considered the world's most important parasitic infection. The global impact of malaria is incalculable and appears to be worsening over the past decades. Although most of this burden of disease is carried by developing tropical countries, cases of imported malaria acquired by international travel are increasingly reported. These numbers are growing because of increased travel to malaria-endemic areas and also due to increased risk of transmission in these areas. Indeed, travel has contributed to the global spread of malaria during the history of humankind. Travellers visiting malaria risk areas should use both personal protective measures and chemoprophylaxis. Non-adherence to chemoprophylactic regimens is frequently secondary to drug side-effects. Therefore, a careful risk-benefit analysis on the use of antimalarial prophylaxis should be carried out in every individual travelling to malaria risk areas. Standby malaria self-treatment represents an alternative in some travellers. However, carefully selected and geographically specific antimalarial drug regimens should be recommended to non-immune people travelling to high-risk areas.

Do travelers really take their mefloquine malaria chemoprophylaxis? Estimation of adherence by an electronic pillbox

BACKGROUND

Nonadherence to chemoprophylaxis could explain why some travelers get malaria. Adherence is notoriously difficult to assess, and most studies have been conducted using questionnaires. This study aims at assessing continuous adherence more accurately with the help of an electronic pillbox.

METHODS

Adult travelers to sub-Saharan Africa had to fill a questionnaire on demographic and travel data, drug intake, and adverse events. They received oral and written information about malaria and mefloquine prophylaxis and a Medication Event Monitoring System (MEMS, Aardex, Zug, Switzerland), ie, a bottle closed with a cap containing a microprocessor recording date and time of all openings, filled with the exact number of mefloquine 250 mg tablets (Lariam, Roche Reinach, Switzerland). The MEMS) was returned with the questionnaire after completion of chemoprophylaxis.

RESULTS

According to the MEMS, only 26 of 81 travelers (32.1%) took all the doses at the expected date, another 8 (9.9%) did so but starting late with the first dose, and 19 others (23.5%) took all the pills but with intervals of +/-1 day from the right date. Another eight (9.9%) took all the pills but in a random way. The remaining 20 travelers (24.7%) missed some doses, mainly after return. Strict adherence as assessed by electronic monitoring was therefore lower than adherence measured by questionnaire (32.1% vs 48% in taking all the tablets on the right day). There was no difference between the two methods when a broader definition of adherence was applied [taking all the tablets on the right day (+/-1 day); 53/81 (65.4%)], but the MEMS showed that some answers to the questionnaire were not reliable.

CONCLUSION

The use of electronic pillboxes confirms the low adherence of travelers to mefloquine chemoprophylaxis in spite of extensive information about the disease and its prevention. Electronic assessment of pill taking, for the first time applied to malaria chemoprophylaxis, gives new insights into the real adherence of travelers.

Schmerzloser Ikterus nach Urlaub in Tansania

The side effects caused by malaria prophylaxis with mefloquine (Lariam) are well known. We describe the case of a 42-year-old female Caucasian patient suffering from painless jaundice and showing elevated liver, cholestasis and inflammation laboratory findings 7 days after returning from Tanzania. Acute cholecystitis was diagnosed by ultrasound. Treatment with parenteral nutrition and antibiotic therapy did not show any beneficial effect. Excluding the possibility of infectious diseases, the elevated laboratory and ultrasound findings were normalized after the discontinuation of the malaria prophylaxis.

The Risk of Severe Depression, Psychosis or Panic Attacks with Prophylactic Antimalarials

INTRODUCTION/OBJECTIVE

Experimental and observational studies have linked mefloquine use to an increased risk of developing neuropsychiatric adverse effects such as depression or psychoses. Most of these reports relied on interview-based information from travellers. We conducted a population-based observational study using a database of medical records to quantify and compare the risk of psychiatric disorders during or after use of mefloquine with the risk during use of proguanil and/or chloroquine, or doxycycline.

STUDY DESIGN/METHODS

The study population was drawn from the large UK-based General Practice Research Database (GPRD). Subjects were aged from 17-79 years and were exposed to mefloquine, proguanil, chloroquine or doxycycline (or a combination of these drugs) at some time between 1990 and 1999. We performed a person-time and a nested case-control analysis to assess the risk of developing a first-time diagnosis of depression, psychosis or panic attack during or after use of these antimalarial drugs.

RESULTS

Within the study population of 35 370 subjects (45.2% males), we identified 580 subjects with a first-time diagnosis of depression (n = 505), psychosis (n = 16) or panic attack (n = 57) and two subjects committed suicide. The incidence rates of first-time diagnoses of depression during current use of mefloquine, proguanil and/or chloroquine, or doxycycline, adjusted for age, gender and calendar year, were 6.9 (95% CI 4.5-10.6), 7.6 (95% CI 5.5-10.5) and 9.5 (95% CI 3.7-24.1)/1000 person-years, respectively. The incidence rates of psychosis or panic attacks during current mefloquine exposure were 1.0/1000 person-years (95% CI 0.3-2.9) and 3.0/1000 person-years (95% CI 1.6-5.7), respectively, approximately 2-fold higher (statistically nonsignificant) than during current use of proguanil and/or chloroquine, or doxycycline. The nested case-control analysis encompassed 505 cases with depression and 3026 controls, 16 cases with psychosis and 96 controls, and 57 cases with a panic attack and 342 controls. Current use of mefloquine was not associated with an elevated risk of developing depression. In a comparison between patients currently using mefloquine with all past users of antimalarials combined, the risk estimate was elevated for current users of mefloquine for both psychosis (odds ratio [OR] 8.0, 95% CI 1.0-62.7; p < 0.05) and panic attacks (OR 2.7, 95% CI 1.1-6.5; p < 0.05).

CONCLUSION

The absolute risk of developing psychosis or panic attack appears low with all the antimalarials tested. No evidence was found in this large observational study that mefloquine use increased the risk of first-time diagnosis of depression when compared with the use of other antimalarials investigated in this study.

Plasmodium vivax malaria in spite of atovaquone/proguanil (malarone) prophylaxis

A 70-year-old male scientist, who had returned 5 weeks earlier from Ethiopia, was admitted to the hospital with symptoms consistent with malaria. On physical examination, he had orthostatic hypotension. He was dehydrated and showed a mild clinical delirium. Abdominal examination revealed a possible spleen tip, and he had petechial lesions bilaterally below his knees. Laboratory data revealed his white blood cell count to be 4,500/mL, with 67% polymorphonuclear cells and 15% band forms. The hemoglobin level was 13.9 g/dL, and the platelet count was low, at 32,000/mL.

The prevention of malaria

Long before the advent of modern chemoprophylaxis drugs, many practitioners successfully prevented the debilitating and fatal outcomes associated with infection by the Plasmodium parasites that cause malaria. Today, with effective insect repellents and several excellent medications available for chemoprophylaxis, there has never been a better array of quality products to prevent mosquito bites and infection and to suppress parasites once in the blood stream; however, there are thousands of imported cases into nonendemic countries and scores of deaths and near-fatal outcomes every year in returning travelers, soldiers, immigrants, and refugees. In this article, the author focuses on practical uses of currently available prevention tools.

Adverse effects of the antimalaria drug, mefloquine: due to primary liver damage with secondary thyroid involvement?

BACKGROUND

Mefloquine is a clinically important antimalaria drug, which is often not well tolerated. We critically reviewed 516 published case reports of mefloquine adverse effects, to clarify the phenomenology of the harms associated with mefloquine, and to make recommendations for safer prescribing.

PRESENTATION

We postulate that many of the adverse effects of mefloquine are a post-hepatic syndrome caused by primary liver damage. In some users we believe that symptomatic thyroid disturbance occurs, either independently or as a secondary consequence of the hepatocellular injury. The mefloquine syndrome presents in a variety of ways including headache, gastrointestinal disturbances, nervousness, fatigue, disorders of sleep, mood, memory and concentration, and occasionally frank psychosis. Previous liver or thyroid disease, and concurrent insults to the liver (such as from alcohol, dehydration, an oral contraceptive pill, recreational drugs, and other liver-damaging drugs) may be related to the development of severe or prolonged adverse reactions to mefloquine.

IMPLICATIONS

We believe that people with active liver or thyroid disease should not take mefloquine, whereas those with fully resolved neuropsychiatric illness may do so safely. Mefloquine users should avoid alcohol, recreational drugs, hormonal contraception and co-medications known to cause liver damage or thyroid damage. With these caveats, we believe that mefloquine may be safely prescribed in pregnancy, and also to occupational groups who carry out safety-critical tasks.

TESTING

Mefloquine's adverse effects need to be investigated through a multicentre cohort study, with small controlled studies testing specific elements of the hypothesis.

Extracts from "Clinical Evidence". Malaria: prevention in travellers

DEFINITION

Malaria is caused by a protozoan infection of red blood cells with one of four species of the genus plasmodium: P falciparum, P vivax, P ovale, or P malariae. Clinically, malaria may present in different ways, but it is usually characterised by fever (which may be swinging), tachycardia, rigors, and sweating. Anaemia, hepatosplenomegaly, cerebral involvement, renal failure, and shock may occur. INCIDENCE/PREVALENCE: Each year there are 300-500 million clinical cases of malaria. About 40% of the world's population is at risk of acquiring the disease. Each year 25-30 million people from non-tropical countries visit areas in which malaria is endemic, of whom between 10,000 and 30,000 contract malaria. AETIOLOGY/RISK FACTORS: Malaria is mainly a rural disease, requiring standing water nearby. It is transmitted by bites from infected female anopheline mosquitoes, mainly at dusk and during the night. In cities, mosquito bites are usually from female culicene mosquitoes, which are not vectors of malaria. Malaria is resurgent in most tropical countries and the risk to travellers is increasing.

PROGNOSIS

Ninety per cent of travellers who contract malaria do not become ill until after they return home. "Imported malaria" is easily treated if diagnosed promptly, and it follows a serious course in only about 12% of people. The most severe form of the disease is cerebral malaria, with a case fatality rate in adult travellers of 2-6%, mainly because of delays in diagnosis.

AIMS

To reduce the risk of infection; to prevent illness and death.

OUTCOMES

Rates of malarial illness and death, and adverse effects of treatment. Proxy measures include number of mosquito bites and number of mosquitoes in indoor areas. We found limited evidence linking number of mosquito bites and risk of malaria.

METHODS

Clinical Evidence search and appraisal in November 1999. We reviewed all identified systematic reviews and randomised controlled trials (RCTs).

Reported side effects to chloroquine, chloroquine plus proguanil, and mefloquine as chemoprophylaxis against malaria in Danish travelers

BACKGROUND

The aim of the study was to provide data on the relative frequency of reported symptoms in travelers using chloroquine, chloroquine plus proguanil, and mefloquine.

METHOD

The study was an open, nonrandomized study recording self-reported events in travelers recruited consecutively from two travel clinics in Copenhagen, Denmark. The main outcome measures were the relative proportion of travelers reporting particular symptoms in the three prophylaxis groups, compliance, hospitalization and premature termination of the travel.

RESULTS

From May 1996 to April 1998 5, 446 travelers were included and 4,158 questionnaires (76.3%) returned. Compliance was significantly better in mefloquine users with 83.3% of short term travelers compared to 76.3% in chloroquine plus proguanil users. Also, 84.8%, 59.3% and 69.5% using chloroquine, chloroquine plus proguanil, and mefloquine respectively reported no symptoms and 0.6%, 1.1% and 2.8% reported "unacceptable" symptoms. Compared to chloroquine, mefloquine users had a significantly higher risk of reporting depression, RR 5.06 (95% CI 2.71 - 9.45), "strange thoughts," RR 6.36 (95% CI 2.52 - 16.05) and altered spatial perception, RR 3.00 (95% CI 1.41 - 6.41).

CONCLUSION

Overall mefloquine is tolerated at least as well as chloroquine plus proguanil and shows better compliance, however, symptoms related to the central nervous system are more prevalent in mefloquine users and when symptoms develop, they are perceived as more severe.

Neuropsychiatric problems in 2,500 long-term young travelers to the tropics

BACKGROUND

The prevalence and features of travel associated neuropsychiatric problems (NPP) and their relation to previous psychological consultations, antimalarials and recreational drug use have not been adequately studied.

METHODS

A two-phase postal and telephone survey has been conducted among 2,500 young travelers to tropical countries. We measured the rate and duration of NPP, characterized their features, and their association with previous psychological profiles, itinerary, type of travel, consumption of recreational drugs, and malaria prophylaxis.

RESULTS

First phase: Out of 1,340 respondents, 151 (11.3%) indicated that they had NPP during travel, in contrast with 2.3% who needed psychological consultation before travel (p<.001). Second phase: 117 of 151 responded to the study questionnaire. The mean age of the respondents was 24.4 years, 54.7% were female, and the mean stay abroad was 5.3 months. The most common NPP were sleeping disturbances (52.1%), fatigue (48.7%) and dizziness (39.3%). Thirty-three travelers (2.5%) had severe symptoms, and 16 (1.2%) had symptoms lasting more than 2 months. Seven travelers had pure or mixed depressive symptoms. Consumption of recreational drugs was admitted by 22.2%. Mefloquine was used significantly more often by those who suffered NPP, than by the entire cohort (98.2% vs. 70.7%; p<.001).

CONCLUSIONS

Long-term travel to the tropics was associated, in this cohort, with a considerable rate of neuropsychiatric symptoms. The majority of the responding travelers were females, used mefloquine as prophylaxis, and at least one fifth used recreational drugs.

Mefloquine for preventing malaria in non-immune adult travellers

OBJECTIVES

Mefloquine has now largely replaced earlier malaria prophylaxis drugs which are no longer considered to be effective against all Plasmodium species, due to parasite resistance. However mefloquine may be associated with neuropsychological harmful effects. The objective of this review was to assess the effects of mefloquine in adult travellers.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group trials register, Medline, Embase, Lilacs, Science Citation Index and reference lists of articles. We contacted researchers in the subject of malaria chemoprophylaxis, and drug companies.

SELECTION CRITERIA

Randomised trials comparing mefloquine with other standard prophylaxis or placebo in non-immune adult travellers.

DATA COLLECTION AND ANALYSIS

The two reviewers independently assessed trial quality and extracted data. Study authors were also contacted.

MAIN RESULTS

Ten trials involving 2750 non-immune adult travellers were included. One trial comparing mefloquine with placebo showed mefloquine prevented malaria episodes in an area of drug resistance (odds ratio 0.04, 95% confidence interval 0.02 to 0.08). Withdrawals in the mefloquine group were consistently higher in four placebo controlled trials (odds ratio 3. 56, 95% confidence interval 1.67 to 7.60). In five trials comparing mefloquine with other chemoprophylaxis, no difference in tolerability was detected.

REVIEWER'S CONCLUSIONS

Mefloquine prevents malaria, but there is not enough evidence to evaluate its tolerability and toxicity, particularly for general travellers.

Cognitive predictors of adherence to malaria prophylaxis regimens on return from a malarious region: a prospective study

Cases of 'imported malaria' into countries where malaria is not endemic are increasing and evidence suggests that non-use of malaria prophylaxis and lack of adherence are contributing to this increase. Non-adherence may be especially likely because chemoprophylaxis regimens require travellers to continue to take medication for 4 weeks after their return from a malarious region. This study investigated the extent to which cognition measures specified by the theory of planned behaviour and the health belief model could distinguish between those who reported greater or lesser adherence after their return. Cognitions were measured using a brief questionnaire on the day of departure from the malarious region and reports of adherence were collected between 5 and 7 weeks later. Data from two longitudinal samples of UK tourists returning from The Gambia were analysed; 106 mefloquine users and 61 chloroquine and proguanil users. Results suggested that malaria prophylaxis adherence could be improved. 22.5% of mefloquine users and 31% of chloroquine and proguanil users reported adherence for 3 weeks or less. A model based on the theory of planned behaviour explained approximately 50% of the variance in reported adherence amongst mefloquine users and 40% amongst chloroquine and proguanil users, comparing favorably with other published applications of the theory. Findings suggest that targeting key cognitions could enhance adherence on return from malarious regions. Enhancing perceived control over adherence may be important as well as emphasising susceptibility to malaria infection. Reassuring mefloquine users concerning potential side effects of the drug may also encourage adherence on return. Implications for future research are discussed.

Compliance of malaria chemoprophylaxis among travelers to India

BACKGROUND

Compliance is an important issue in malaria chemoprophylaxis. The objective of the study was to determine reasons for noncompliance with chemoprophylaxis among international travelers to India.

METHODS

A group of 452 subjects traveling in the subcontinent were interviewed by directly administered questionnaire at two selected locations in Calcutta during October 1992. Full compliance was defined as the uninterrupted use of drugs, as per the World Health Organization (WHO) schedule, during travel up to the date of interview.

RESULTS

Overall, the sample had a male preponderance (61%), with 155 (34%) being business travelers and 56% traveling for more than 3 weeks. Of the 158 (35%) reporting illness during travel, 5 persons tested positive for malaria. Compliance with chemoprophylaxis noted among 320 (71%) respondents in comparison to 21 (5%) found taking inadequate dosage or incorrect medication and 111 (24%) travelers being without any drugs. Backpackers and ethnic travelers as a group reported lower usage. Female, first visit and long-term travelers were less compliant. Inadequacy in pretravel advice, discontinuation due to side effects and active decision despite pretravel advice were common reasons for noncompliance. Past travel experience, concern for side effects, perceived uselessness and confusion arising from alternative regimens were also found to have influenced the decision making.

CONCLUSION

We need to address the identified areas of conflict especially during pretravel counseling since improving compliance is our primary goal in malaria prevention among travelers today.

A week in the life of a travel clinic

International travel has increased enormously in recent years. With the greater movement of people have come increased encounters with a wide variety of diseases: malaria, dengue, cholera, typhoid fever, Ebola virus, and many more. The need for greater scope, consistency, and knowledgeability in pretravel health care to meet these challenges has been met by the emergence of the discipline of travel medicine. Travelers are well advised to become informed of the risks they face and to take steps to minimize those risks. After reviewing a traveler's medical history and a detailed itinerary, a travel medicine practitioner can offer expert advice on behavioral modifications, immunizations, and chemoprophylaxis regimens which will increase the traveler's margin of safety. The issues most frequently addressed in a travel clinic include treatment of traveler's diarrhea, malaria chemoprophylaxis, and immunizations, for hepatitis A, typhoid fever, tetanus/diphtheria, influenza, pneumococcus, hepatitis B, polio, meningococcus, measles, mumps, rubella, varicella, and rabies. Pretravel consultation must consider the age and underlying health problems of the traveler, the nature of the trip (wilderness, jungle, rural, urban, resort, or cruise), the duration of travel, and the latest available information on the site in terms of disease outbreaks, terrorism, and natural calamities.