Malaria risk in travelers

Malaria diagnosis using a combined system of a simple and fast extraction method with a lyophilised Dual-LAMP assay in a non-endemic setting

Malaria is a parasitic disease distributed in tropical areas but with a high number of imported cases in non-endemic countries. The most specific and sensitive malaria diagnostic methods are PCR and LAMP. However, both require specific equipment, extraction procedures and a cold chain. This study aims to solve some limitations of LAMP method with the optimization and validation of six LAMP assays, genus and species-specific, using an easy and fast extraction method, the incorporation of a reaction control assay, two ways (Dual) of result reading and reagent lyophilization. The Dual-LAMP assays were validated against the Nested-Multiplex Malaria PCR. A conventional column and saline extraction methods, and the use of lyophilized reaction tubes were also assessed. A new reaction control Dual-LAMP-RC assay was designed. Dual-LAMP-Pspp assay showed no cross-reactivity with other parasites, repeatability and reproducibility of 100%, a significant correlation between parasite concentration and time to amplification and a LoD of 1.22 parasites/µl and 5.82 parasites/µl using column and saline extraction methods, respectively. Sensitivity and specificity of the six Dual-LAMP assays reach values of 100% or close to this, being lower for the Dual-LAMP-Pm. The Dual-LAMP-RC assay worked as expected. Lyophilized Dual-LAMP results were concordant with the reference method. Dual-LAMP malaria assays with the addition of a new reaction control LAMP assay and the use of a fast and easy saline extraction method, provided low limit of detection, no cross-reactivity, and good sensitivity and specificity. Furthermore, the reagent lyophilization and the dual result reading allow their use in most settings.

The oral repellent - science fiction or common sense? Insects, vector-borne diseases, failing strategies, and a bold proposition

Over the last decades, unimaginable amounts of money have gone into research and development of vector control measures, repellents, treatment, and vaccines for vector borne diseases. Technological progress and scientific breakthroughs allowed for ever more sophisticated and futuristic strategies. Yet, each year, millions of people still die or suffer from potentially serious consequences of malaria or dengue to more recent infections, such as zika or chikungunya, or of debilitating consequences of neglected tropical diseases. This does not seem value for money. In addition, all current vector control strategies and personal protection methods have shortcomings, some serious, that are either destructive to non-target species or unsatisfactory in their effectiveness. On the other hand, the rapid decline in insect populations and their predators reflects decades-long aggressive and indiscriminate vector control. This major disruption of biodiversity has an impact on human life not anticipated by the well-meaning killing of invertebrates. The objective of this paper is to re-examine current control methods, their effectiveness, their impact on biodiversity, human and animal health, and to call for scientific courage in the pursuit of fresh ideas. This paper brings together topics that are usually presented in isolation, thereby missing important links that offer potential solutions to long-standing problems in global health. First, it serves as a reminder of the importance of insects to human life and discusses the few that play a role in transmitting disease. Next, it examines critically the many currently employed vector control strategies and personal protection methods. Finally, based on new insights into insect chemo-sensation and attractants, this perspective makes a case for revisiting a previously abandoned idea, the oral repellent, and its use via currently successful methods of mass-application. The call is out for focused research to provide a powerful tool for public health, tropical medicine, and travel medicine.

Usefulness of a commercial LAMP assay for detection of malaria infection, including Plasmodium knowlesi cases, in returning travelers in Spain

Objective

Main malaria diagnosis is based on microscopic examination combined with rapid diagnostic tests. Both methods have low sensitivity and specificity. Loop-mediated isothermal amplification techniques have shown a sensitivity similar to PCR but with lower times of performance. This study aimed to assess a commercial LAMP for the diagnosis of malaria (Alethia® Malaria) against the Nested-Multiplex-Malaria PCR, including the analytical sensitivity and the operational characteristics.

Results

One hundred five samples out of 114 rendered valid results, obtaining 85 positive samples and 18 negative samples with an agreement of 98% compared to the reference method with a sensitivity, specificity and kappa coefficient of 98.84%, 94.74% and 0.94 respectively, with only two discrepant samples. The turnaround time was estimated in 1 h and 30 min, with a cost of 32.67€ per determination. The results showed several advantages of the Alethia® Malaria, as it was easy to perform, minimal training requirement and 40 min run. Moreover, it includes an internal control to avoid false negatives. However, it also showed some limitations such as the need for a specific amplification and detection device, the detection of only Plasmodium spp. and a very high price.

Usefulness of Malachite-Green LAMP for Diagnosis of Plasmodium and Five Human Malaria Species in a Nonendemic Setting

Molecular methods are necessary to detect low-density malaria infections. The purpose of this study was to assess the diagnostic performance of six malachite-green loop-mediated amplification method (MG-LAMP) assays (MG-LAMP-Pf, MG-LAMP-Pv, MG-LAMP-Po, MG-LAMP-Pm, MG-LAMP-Pk, and MG-LAMP-Pspp) for the species-specific detection of each human Plasmodium, including P. knowlesi, and the Plasmodium genus compared with the nested-multiplex malaria polymerase chain reaction (NM-PCR), using 161 malaria-positive and 274 malaria-negative samples. MG-LAMP-Pspp assay detected the five human Plasmodium species and each species-specific MG-LAMP assay detected only its corresponding species. Sensitivity, specificity, and predictive values of MG-LAMP assays, compared with NM-PCR, were > 90%, except in the case of the MG-LAMP-Pm assay, which dropped to 47%. Limit of detection for MG-LAMP-Pspp assay ranged from 0.1 parasites/µL for P. falciparum to 16.9 parasites/µL for P. malariae samples, and it was similar for the rest of MG-LAMP assays except for the MG-LAMP-Pm assay. Turnaround time was estimated to be 2 hours and 35 minutes for one MG-LAMP assay and 4 hours and 15 minutes if all species-specific MG-LAMP is set up, whereas for the NM-PCR, turnaround time was ∼6 hours and 15 minutes. Costs per determination ranged from 1 to 6 euros for MG-LAMP assays and 5 euros for NM-PCR. Therefore, MG-LAMP assays appear to have good concordance compared with the reference method, except for the MG-LAMP-Pm assay. They can detect low parasitemia and identify malaria species, with lower costs and shorter time to obtain results, and they are suitable tools to be used in endemic and non-endemic countries for malaria detection.

The risk of malaria infection for travelers visiting the Brazilian Amazonian region: A mathematical modeling approach

BACKGROUND

Human mobility between malaria endemic and malaria-free areas can hinder control and elimination efforts in the Amazon basin, maintaining Plasmodium circulation and introduction to new areas.

METHODS

The analysis begins by estimating the incidence of malaria in areas of interest. Then, the risk of infection as a function of the duration of stay after t₀ was calculated as the number of infected travelers over the number of arrived travelers. Differential equations were employed to estimate the risk of nonimmune travelers acquiring malaria in Amazonian municipalities. Risk was calculated as a result of the force of the infection in terms of local dynamics per time of arrival and duration of visit.

RESULTS

Maximum risk occurred at the peak or at the end of the rainy season and it was nonlinearly (exponentially) correlated with the fraction of infected mosquitoes. Relationship between the risk of malaria and duration of visit was linear and positively correlated. Relationship between the risk of malaria and the time of arrival in the municipality was dependent on local effects of seasonality.

CONCLUSIONS

The risk of nonimmune travelers acquiring malaria is not negligible and can maintain regional circulation of parasites, propagating introductions in areas where malaria has been eliminated.

Risk perception of health problems among travelers visiting a travel clinic in Bangkok, Thailand

BACKGROUND

Effective pre-travel consultations cannot be achieved only through individual risk assessment and advice on vaccinations and chemoprophylaxis. Travelers' perceptions of the risk of health problems represent another key factor in successful risk communication and co-operation with pre-travel advice. The objective of this study was to determine perception of travel-related health risks among Thais and westerners visiting the Thai Travel Clinic for consultation before visiting developing countries.

METHODS

A novel pictorial scale questionnaire-based study was conducted with both Thai and western travelers who visited the Thai Travel Clinic for pre-travel consultation. All participants were approached before and after completing the consultation, and were asked about their demographic data and perceptions of travel-related health risk. The perceptions of risk before and after consultation were compared using the McNemar test, and were also compared with the actual estimated risk.

RESULTS

During May to November 2019, 594 travelers (330 Thais and 264 Westerners) were enrolled and completed the pictorial scale questionnaires. Most Thai travelers visited Africa/South America (63%), and 20% had previously received counseling. Westerners were mostly backpackers (37.5%), traveling for > 30 days (71.6%), while 43.6% had previously received counseling. Overall, the westerners (n = 264) changed their risk perceptions slightly after counseling in contrast with the Thais. The change in perception of most health problems was observed statistically significant (p-value < 0.05) after receiving pre-travel consultation among both groups of travelers. Risk perception among western travelers after consultation compared with estimated actual risk showed accurate risk perception toward most of health problems especially in travelers who had previously received counseling in ones' home countries.

CONCLUSIONS

Risk perception of health problems plays an important role in successful risk communication and their response to pre-travel advices. Differences in risk perceptions were evident between the two groups. Therefore, this highlight the importance of obtaining pre-travel advice in one's home country before travelling. Raised awareness of the risks should be emphasized during consultations for underestimated health risks, especially for rabid animal exposure and sexually transmitted diseases.

Incidence of health problems in travelers to Southeast Asia: a prospective cohort study

BACKGROUND

There are few studies of the incidence of health problems among travelers to Southeast Asia. The current study sought to determine the incidence of self-reported health problems among travelers visiting the region.

METHODS

A prospective questionnaire-based study was conducted among travelers from high-income countries who visited Southeast Asia. Participants were enrolled at time of their pre-travel visit at Mahidol University, Bangkok, Thailand. Travelers were prospectively followed by self-administered questionnaires 2 weeks after arrival, upon return to their home country and 2 weeks after return.

RESULTS

During January 2018-February 2019, 359 travelers were enrolled in Bangkok, Thailand, and the first questionnaire was administered. Follow-up questionnaires were returned by 191, 96 and 64 participants 2 weeks later, at the end of the trip and 2 weeks after return, respectively. A total of 6094 travel days were included in the final analysis. The incidence of acute diarrhea per month per 1000 travelers was 217 [95% confidence interval (CI), 189-248] episodes; skin problems, 197 (95% CI, 170-227); respiratory symptoms, 133 (95% CI, 111-158); fever, 49 (95% CI, 36-65); and potential rabies exposure, 34 (95% CI, 24-48). The incidence of acute diarrhea episodes per month per 1000 travelers was significantly higher during the first 2 weeks of travel compared with subsequent weeks of travel: 325 (95% CI, 291-362) vs 132 (95% CI, 110-1157) (P < 0.05). The incidence of outpatient visits and hospitalizations per month per 1000 travelers was 49 (95% CI, 36-65) and 5 (95% CI, 2-10), respectively.

CONCLUSIONS

In this prospective cohort study we observed substantial burden of acute diarrhea and skin and respiratory symptoms among travelers to Southeast Asia. The higher incidence of diarrhea in the first 2 weeks of travel should be further investigated.

Imported cases of malaria in Spain: observational study using nationally reported statistics and surveillance data, 2002-2015

Background

Malaria was eliminated in Spain in 1964. Since then, more than 10,000 cases of malaria have been reported, mostly in travellers and migrants, making it the most frequently imported disease into this country. In order to improve knowledge on imported malaria cases characteristics, the two main malaria data sources were assessed: the national surveillance system and the hospital discharge database (CMBD).

Methods

Observational study using prospectively gathered surveillance data and CMBD records between 2002 and 2015. The average number of hospitalizations per year was calculated to assess temporal patterns. Socio-demographic, clinical and travel background information were analysed. Bivariate and multivariable statistical methods were employed to evaluate hospitalization risk, fatal outcome, continent of infection and chemoprophylaxis failure and their association with different factors.

Results

A total of 9513 malaria hospital discharges and 7421 reported malaria cases were identified. The number of reported cases was below the number of hospitalizations during the whole study period, with a steady increase trend in both databases since 2008. Males aged 25–44 were the most represented in both data sources. Most frequent related co-diagnoses were anaemia (20.2%) and thrombocytopaenia (15.4%). The risks of fatal outcome increased with age and were associated with the parasite species (Plasmodium falciparum). The main place of infection was Africa (88.9%), particularly Equatorial Guinea (33.2%). Most reported cases were visiting friends and relatives (VFRs) and immigrants (70.2%). A significant increased likelihood of hospitalization was observed for children under 10 years (aOR:2.7; 95% CI 1.9–3.9), those infected by Plasmodium vivax (4.3; 95% CI 2.1–8.7) and travellers VFRs (1.4; 95% CI 1.1–1.7). Only 4% of cases reported a correct regime of chemoprophylaxis. Being male, over 15 years, VFRs, migrant and born in an endemic country were associated to increased risk of failure in preventive chemotherapy.

Conclusions

The joint analysis of two data sources allowed for better characterization of imported malaria profile in Spain. Despite the availability of highly effective preventive measures, the preventable burden from malaria is high in Spain. Pre-travel advice and appropriately delivered preventive messages needs to be improved, particularly in migrants and VFRs.

Sex- and age patterns in incidence of infectious diseases in Germany: analyses of surveillance records over a 13-year period (2001-2013)

Sex differences in the incidence of infections may indicate different risk factors and behaviour but have not been analysed across pathogens. Based on 3.96 million records of 33 pathogens in Germany, notified from 2001 to 2013, we applied Poisson regression to generate age-standardised incidence rate ratios and assessed their distribution across age and sex. The following trends became apparent: (a) pathogens with male incidence preponderance at infant and child age (meningococcal disease (incidence rate ratio (IRR) = 1.19, 95% CI 1.03-1.38, age = 0-4); influenza (IRR = 1.09, 95% CI 1.06-1.13, age = 0-4)), (b) pathogens with sex-switch in incidence preponderance at puberty (e.g. norovirus (IRR = 1.10, 95% CI 1.02-1.19 in age = 5-14, IRR = 0.96, 95% CI 0.93-0.99, age ⩾ 60), (c) pathogens with general male incidence preponderance (bacterial/parasitic infections with campylobacter, Yersinia and Giardia), (d) pathogens with male incidence preponderance at juvenile and adult age (sexually transmitted or vector-borne infections (combined-IRR = 2.53, 95% CI 2.36-2.71, age = 15-59), (e) pathogens with male preponderance at older age (tick-borne encephalitis - IRR = 2.75, 95% CI 1.21-6.24, listeriosis - IRR = 2.06, 95% CI 1.38-3.06, age ⩾ 60). Risk factor concepts only partly serve to interpret similarities of grouped infections, i.e. transmission-related explanations and sex-specific exposures not consistently explain the pattern of food-borne infections (b). Sex-specific differences in infectious disease incidence are well acknowledged regarding the sexually transmitted diseases. This has led to designing gender-specific prevention strategies. Our data suggest that for infections with other transmission routes, gender-specific approaches can also be of benefit and importance.

Self-diagnosis of malaria by travellers: a cohort study on the use of malaria rapid diagnostic tests provided by a Swiss travel clinic

Background

The WHO recommends that all suspect malaria cases be tested before receiving treatment. Rapid diagnostic tests (RDT) for malaria can be performed reliably by community health workers with no formal medical background and thus, RDTs could also be provided to travellers for self-diagnosis during visits to endemic regions.

Methods

RDTs were proposed during pre-travel consultations to pre-defined categories of travellers. A training run on their own blood was performed and, if carried out correctly, the traveller was given a written procedure on how to perform the test and act on its result. The travellers were then proposed to buy a malaria RDT kit and were interviewed upon their return.

Results

From February 2012 to February 2017, 744 travellers were proposed RDTs and 692 performed the training run (one could not complete it due to a hand tremor). Among the 691 subjects included, 69% travelled to moderate- or low-risk areas of malaria, 18% to high-risk areas and 13% to mixed-risk areas. The two most frequent categories of travellers to whom RDTs were proposed were long-term travellers (69%) and those travelling to remote areas (57%). 543 travellers (79%) were interviewed upon return. During their trip, 17% (91/543) had a medical problem with fever and 12% (65/543) without fever. Among 91 febrile patients, 57% (52/91) performed an RDT, 22% (20/91) consulted immediately without using the test, and 21% (19/91) did neither. Four RDTs (4/52; 8%) were positive: 2 in low-risk and 2 in high-risk areas (0.7% attack rate of self-documented malaria). Two travellers could not perform the test correctly and attended a facility or took standby emergency treatment. Four travellers with negative results repeated the test after 24 h; all were still negative. Carrying RDTs made travellers feel more secure, especially when travelling with children.

Conclusions

1/6 travellers experienced fever and 4/5 of those reacted appropriately: more than half used RDTs and a quarter consulted immediately. Four travellers (including 2 from low-risk areas) diagnosed themselves with malaria and self-treated successfully. This strategy allows prompt treatment for malaria in high-risk groups and may avoid over-diagnosis (and subsequent inappropriate treatment) of malaria on-site.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-2079-2) contains supplementary material, which is available to authorized users.

Self-reported infections during international travel and notifiable infections among returning international travellers, Sweden, 2009-2013

We studied food and water-borne diseases (FWDs), sexually transmitted diseases (STDs), vector-borne diseases (VBDs) and diseases vaccinated against in the Swedish childhood vaccination programme among Swedish international travellers, in order to identify countries associated with a high number of infections. We used the national database for notifiable infections to estimate the number of FWDs (campylobacteriosis, salmonellosis, giardiasis, shigellosis, EHEC, Entamoeba histolytica, yersinosis, hepatitis A, paratyphoid fever, typhoid fever, hepatitis E, listeriosis, cholera), STIs (chlamydia, gonorrhoea and acute hepatitis B), VBDs (dengue fever, malaria, West Nile fever, Japanese encephalitis and yellow fever) and diseases vaccinated against in the Swedish childhood vaccination programme (pertussis, measles, mumps, rubella, diphtheria) acquired abroad 2009–2013. We obtained number and duration of trips to each country from a database that monthly collects travel data from a randomly selected proportion of the Swedish population. We calculated number of infections per country 2009–2013 and incidence/million travel days for the five countries with the highest number of infections. Thailand had the highest number of FWDs (7,697, incidence 191/million travel days), STIs (1,388, incidence 34/million travel days) and VBDs (358, incidence 9/million travel days). France had the highest number of cases of diseases vaccinated against in the Swedish childhood vaccination programme (8, 0.4/million travel days). Swedish travellers contracted most infections in Thailand. Special focus should be placed on giving advice to travellers to this destination.

Attenuated PfSPZ Vaccine induces strain-transcending T cells and durable protection against heterologous controlled human malaria infection

A live-attenuated malaria vaccine, Plasmodium falciparum sporozoite vaccine (PfSPZ Vaccine), confers sterile protection against controlled human malaria infection (CHMI) with Plasmodium falciparum (Pf) parasites homologous to the vaccine strain up to 14 mo after final vaccination. No injectable malaria vaccine has demonstrated long-term protection against CHMI using Pf parasites heterologous to the vaccine strain. Here, we conducted an open-label trial with PfSPZ Vaccine at a dose of 9.0 × 10⁵ PfSPZ administered i.v. three times at 8-wk intervals to 15 malaria-naive adults. After CHMI with homologous Pf parasites 19 wk after final immunization, nine (64%) of 14 (95% CI, 35-87%) vaccinated volunteers remained without parasitemia compared with none of six nonvaccinated controls (P = 0.012). Of the nine nonparasitemic subjects, six underwent repeat CHMI with heterologous Pf7G8 parasites 33 wk after final immunization. Five (83%) of six (95% CI, 36-99%) remained without parasitemia compared with none of six nonvaccinated controls. PfSPZ-specific T-cell and antibody responses were detected in all vaccine recipients. Cytokine production by T cells from vaccinated subjects after in vitro stimulation with homologous (NF54) or heterologous (7G8) PfSPZ were highly correlated. Interestingly, PfSPZ-specific T-cell responses in the blood peaked after the first immunization and were not enhanced by subsequent immunizations. Collectively, these data suggest durable protection against homologous and heterologous Pf parasites can be achieved with PfSPZ Vaccine. Ongoing studies will determine whether protective efficacy can be enhanced by additional alterations in the vaccine dose and number of immunizations.

Effectiveness of twice a week prophylaxis with atovaquone-proguanil (Malarone®) in long-term travellers to West Africa

BACKGROUND

Current guidelines recommend daily dosing of atovaquone-proguanil (AP), beginning a day before travel to endemic areas and continuing for 7 days after departure. Adherence of long-term travellers to daily malaria chemoprophylaxis tends to be poor, even when residing in highly endemic malaria regions. Evidence from a volunteer challenging study suggests that non-daily, longer intervals dosing of AP provides effective protection against Plasmodium falciparum This study examines the effectiveness of twice weekly AP prophylaxis in long-term travellers to highly endemic P. falciparum areas in West Africa.

METHODS

An observational surveillance study aimed to detect prophylactic failures associated with twice weekly AP, during the years 2013-2014, among long-term expatriates in two sites in West Africa. The expatriates were divided according to the malaria prophylaxis regimen taken: AP twice weekly; mefloquine once weekly and a group refusing to take prophylaxis. Malaria events were recorded for each group. The incidence-density of malaria was calculated by dividing malaria events per number of person-months at risk.

RESULTS

Among 122 expatriates to West Africa the malaria rates were: 11.7/1000 person-months in the group with no-prophylaxis (n = 63); 2.06/1000 person-months in the 40 expatriates taking mefloquine (P = 0.006) and no cases of malaria (0/391 person-months, P = 0.01) in the twice weekly AP group (n = 33).

CONCLUSIONS

No prophylaxis failures were detected among the group of expatriates taking AP prophylaxis twice weekly compared with 11.7/1000 person-months among the no-prophylaxis group. Twice weekly AP prophylaxis may be an acceptable approach for long-term travellers who are unwilling to adhere to malaria chemoprophylaxis guidelines.

Illness and injury of travellers abroad: Finnish nationwide data from 2010 to 2012, with incidences in various regions of the world

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Duration of residency in a non-endemic area and risk of severe malaria in African immigrants

In malaria-endemic areas, adults very rarely succumb to severe malaria, suggesting that immunity to severe disease is life-long under conditions of repeated exposure. To what extent this protection persists in the absence of exposure remains to be established. The aim of this study was to assess whether duration of residency in a malaria-free country affects the risk for severe malaria in immigrants originating from sub-Saharan Africa. We conducted a retrospective chart review of 948 cases of malaria diagnosed in Stockholm, Sweden in 1995-2013. Among 501 adult patients with Plasmodium falciparum (315 of endemic origin and 186 of non-endemic origin, mainly Sweden), 41 (8.2%) had severe malaria according to WHO criteria (including 5% with parasitaemia), 22 (4.4%) had factors prognostic of poor outcome, and 35 (7.0%) were admitted to intensive care. Overall, patient origin did not affect the odds of severe malaria, according to any of these definitions. However, when the immigrants were stratified with regard to their duration of residency in Sweden, the risk of factors prognostic for poor outcome was associated with duration of prior residency in a malaria-free country among patients of endemic origin (p 0.02), and immigrants who had lived for ≥ 15 years in Sweden had a similar risk as non-immune travellers. The results of this explorative study suggest that, although immunity to severe malaria is maintained for several years in African adults, this protection might be lost with time without repeated re-exposure. A larger study, preferably including multiple centres, will be needed to confirm our findings.

Malaria: prevention in travellers (non-drug interventions)

INTRODUCTION

Malaria transmission occurs most frequently in environments with humidity greater than 60% and ambient temperature of 25°C to 30°C. Risks increase with longer visits and depend on activity. Infection can follow a single mosquito bite. Incubation is usually 10 to 14 days but can be up to 18 months, depending on the strain of parasite.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of non-drug interventions to prevent malaria in non-pregnant adult travellers? What are the effects of non-drug interventions to prevent malaria in child travellers and in pregnant travellers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to November 2013 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations, such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found five studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: aerosol insecticides, air conditioning and electric fans, bath or chemical-base oils, biological control measures, dietary supplementation, electronic mosquito repellents, insecticide-treated clothing/nets, lifestyle changes (full-length and light-coloured clothing, behaviour modification), mosquito coils and vapourising mats, skin-applied chemical repellents (containing diethyltoluamide [DEET] or picaridin), skin-applied plant-based repellents, and smoke.

Vaccination and malaria prophylaxis among Greek international travelers to Asian destinations

BACKGROUND

International travel is rapidly increasing worldwide, and the greatest increases have occurred in tropical and subtropical areas. The aim of the survey was to investigate the pre-travel health-seeking practices of travelers to Asian destinations.

METHODS

A questionnaire-based survey was conducted at the Athens International Airport between the 1st of November 2011 and the 30th of April 2013.

RESULTS

A total of 1666 adult travelers participated in the study, and 69.7% were men. The mean age of the participants was 39 years. Previous travel to tropical countries was reported by 69% of the participants. The most frequent destination was the Indian subcontinent (45.0%). The main reasons for travel were visiting friends and relatives (VFRs; 36.5%) and business (32.4%). Most of the participants traveled for <1 month (51.4%). Only 24.5% pursued pre-travel consultations. Vaccinations were administered to 14.4% of the participants, and of those, 77%, 73%, and 32.5% received hepatitis A, tetanus/diphtheria, and typhoid vaccines, respectively. Malaria prophylaxis was given to 12.2% of the participants. Logistic regression analysis revealed that being male and unemployed, having an elementary level of education, traveling to visiting friends and relatives, and short durations of travel were significant determinants of not seeking pre-travel consultations.

CONCLUSION

Significant gaps were revealed in the vaccinations and malaria prophylaxes of travelers departing to Asia. Specific educational tools should be developed to improve the awareness of travelers to high-risk destinations.

Risk factors for UK Plasmodium falciparum cases

BACKGROUND

An increasing proportion of malaria cases diagnosed in UK residents with a history of travel to malaria endemic areas are due to Plasmodium falciparum.

METHODS

In order to identify travellers at most risk of acquiring malaria a proportional hazards model was used to estimate the risk of acquiring malaria stratified by purpose of travel and age whilst adjusting for entomological inoculation rate (EIR) and duration of stay in endemic countries.

RESULTS

Travellers visiting friends and relatives and business travellers were found to have significantly higher hazard of acquiring malaria (adjusted hazard ratio (HR) relative to that of holiday makers 7.4, 95% CI 6.4-8.5, p < 0. 0001 and HR 3.4, 95% CI 2.9-3.8, p < 0. 0001, respectively). All age-groups were at lower risk than children aged 0-15 years.

CONCLUSIONS

These estimates of the increased risk for business travellers and those visiting friends and relatives should be used to inform programmes to improve awareness of the risks of malaria when travelling.

Imported malaria in a non-endemic area: the experience of the university of Campinas hospital in the Brazilian Southeast

BACKGROUND

Although malaria in Brazil almost exclusively occurs within the boundaries of the Amazon Region, some concerns are raised regarding imported malaria to non-endemic areas of the country, notably increased incidence of complications due to delayed diagnoses. However, although imported malaria in Brazil represents a major health problem, only a few studies have addressed this subject.

METHODS

A retrospective case series is presented in which 263 medical charts were analysed to investigate the clinical and epidemiological characterization of malaria cases that were diagnosed and treated at Hospital & Clinics, State University of Campinas between 1998 and 2011.

RESULTS

Amongst all medical charts analysed, 224 patients had a parasitological confirmed diagnosis of malaria. Plasmodium vivax and Plasmodium falciparum were responsible for 67% and 30% of the infections, respectively. The majority of patients were male (83%) of a productive age (median, 37 years old). Importantly, severe complications did not differ significantly between P. vivax (14 cases, 9%) and P. falciparum (7 cases, 10%) infections.

CONCLUSIONS

Severe malaria cases were frequent among imported cases in Brazil outside of the Amazon area. The findings reinforce the idea that P. vivax infections in Brazil are not benign, regardless the endemicity of the area studied. Moreover, as the hospital is located in a privileged site, it could be used for future studies of malaria relapses and primaquine resistance mechanisms. Finally, based on the volume of cases treated and the secondary complications, referral malaria services are needed in the non-endemic areas of Brazil for a rapid and efficient and treatment.

Effectiveness of short prophylactic course of atovaquone-proguanil in travelers to sub-saharan Africa

BACKGROUND

Current guidelines recommend continuation of atovaquone-proguanil (AP) malaria prophylaxis for 7 days after leaving Plasmodium falciparum endemic areas. Evidence from clinical studies suggests that discontinuation of AP 1 day after exposure ends may be safe and effective. Our objective was to assess the effectiveness of short-course AP prophylaxis among travelers to sub-Saharan Africa.

METHODS

To detect prophylactic failures associated with short-course AP prophylaxis discontinued 1 day after return, we conducted active surveillance during the years 2010 and 2011, by a retrospective telephone survey 1 to 6 months after travelers' return. Passive surveillance data were obtained from the Israel Ministry of Health (MOH) malaria registry.

RESULTS

Among 485 travelers to sub-Saharan Africa (cumulative exposure of 4,979 days), 421 (87%) discontinued AP 1 day after leaving the endemic region (cumulative exposure of 4,337 days). None of the 485 travelers reported malaria infection. The MOH malaria registry survey included 363 P. falciparum-infected patients during the years 2003 to 2011. The majority (n = 305; 84%) did not use any malaria prophylaxis. None of the patients had used AP (neither regular nor short course AP) for malaria prophylaxis.

CONCLUSIONS

We did not detect prophylaxis failures among a group of travelers who discontinued AP prophylaxis 1 day after leaving malaria-endemic areas. Passive surveillance in Israel did not detect any P. falciparum cases among AP users. We recommend further validation of our findings by clinical trials, prospective studies, and active surveillance in larger cohorts to assess the effectiveness of short-course AP prophylaxis in travelers.

Malaria in overseas labourers returning to China: an analysis of imported malaria in Jiangsu Province, 2001-2011

Background

While great success in malaria control has been achieved in China, imported malaria has become a major challenge in the context of malaria elimination. This retrospective study describes the epidemiological profile of imported malaria and identifies the at-risk population during the period of 2001–2011 in Jiangsu Province.

Methods

Data on imported malaria cases in Jiangsu Province from 2001 to 2011 were collected from the infectious disease surveillance system and case investigation reports. Epidemiological trends were described and correlations between trends in exported labour and malaria imported from other countries were explored.

Results

From 2001 to 2011, 918 malaria cases and six malaria deaths were due to malaria imported from other countries, accounting for 12.4% of all malaria cases and 100% of all malaria deaths. During this time period the annual number of indigenous cases decreased from 1,163 to 13 while the number of imported cases increased from 86 to 366. The relative proportion of cases imported from other countries versus other provinces also increased from 0.0% (0/86) to 97.0% (350/361). The most affected demographic groups were males (897 cases, 97.7%) and adults (20–50 years old: 857 cases, 93.4%). All 918 cases had a recent travel history to malaria-endemic areas and the main purpose for travel was overseas labour (848 cases, 92.4%). The cases were mainly acquired from African countries (855 cases, 93.1%). Plasmodium falciparum was the most common species (733 cases, 79.8%). The increase in malaria cases imported from other countries was associated with the growth of investment to Africa from Jiangsu (R² = 0.8057) and the increasing number of exported labourers to Africa from Jiangsu (R² = 0.8863).

Conclusions

From 2001 to 2011 in Jiangsu Province, there was a consistent increase in the number of malaria cases imported from other countries while the number of locally acquired cases sharply declined. This trend may be ascribed to the increasing investment from China to Africa and the rising number of Chinese labourers working in Africa. Preventative efforts should be targeted to this high-risk group and the surveillance and response system should be strengthened to prevent local resurgence in Jiangsu.

Malaria burden in irregular migrants returning to Sri Lanka from human smuggling operations in West Africa and implications for a country reaching malaria elimination

BACKGROUND

The number of malaria cases among irregular migrants returning to Sri Lanka has not been investigated.

METHODS

In the first 6 months of 2012 we screened 287 irregular migrants returning from seven West African nations to Sri Lanka for malaria to ascertain the risk of infection during migration.

RESULTS

Four men were diagnosed as having malaria: three with Plasmodium falciparum had travelled to Togo and one with P. vivax had travelled to Guinea. The risk of contracting malaria was 14 cases per 1000.

CONCLUSION

Facilitating a safe return with selective screening for at-risk inbound migrants flows is desirable as Sri Lanka advances towards its goal of malaria elimination.

High attack rate for malaria through irregular migration routes to a country on verge of elimination

Irregular migration in the form of human smuggling and human trafficking is recognized as a global public health issue. Thirty-two cases of Plasmodium falciparum were detected in 534 irregular migrants returning to Sri Lanka via failed human smuggling routes from West Africa in 2012, contributing to the largest burden of imported cases in Sri Lanka as it entered elimination phase. Beyond the criminality and human rights abuse, irregular migration plays an important, but often forgotten, pathway for malaria re-introduction. Active surveillance of the growing numbers of irregular migrant flows becomes an important strategy as Sri Lanka advances towards goals of malaria elimination.

Factors affecting the use of anti-malaria preventive measures among Taiwan immigrants returning to malaria-endemic regions

The aim of this study was to investigate the predictors of anti-malaria preventive measures (AMPMs) among Taiwan immigrants returning to their country of origin using the Health Belief Model (HBM). Between March and May 2011, all permanent immigrants originating from malaria-endemic countries, attended by either the Taipei or Tainan Immigrant Service Center, Taiwan, and who reported a history of returning to their country of origin within the preceding year during the malarious season in their country of origin were enrolled in the study. Complete information was collected from 316 immigrants, with a response rate of 87% (316/364). The mean age of the subjects was 38.1 years (SD = 9.9). The majority (70%) of participants did not receive travel information through a pre-travel consultation; more than 40% reported that they did not use measures to prevent insect bites. Multiple regression analyses revealed that Chinese proficiency, travel consultation before travel, lower perceived susceptibility to malaria, higher perceived severity of malaria infection, higher perceived benefit for taking measures, and higher self-efficacy for taking measures significantly predicted the use of AMPMs during the return to their country of origin (R(2) = 0.20; F = 50.42; P < 0.001). A high proportion of immigrants were not using appropriate AMPMs when they returned to their country. Educational approaches should be targeted toward immigrants who return to visit their country of origin.

Malaria relevance and diagnosis in febrile Burkina Faso travellers: a prospective study

Background

There is a lack of information regarding the epidemiology of malaria among travellers from non-malaria endemic countries to Sahelian areas. The literature provides general statistics about imported malaria in industrialized countries or extensive recommendations about fever management, but none of these recommendations are applicable to developing countries.

Methods

The aim of the study was to evaluate the aetiologies of fever, malaria prevalence, and best diagnostic methods in a population of 306 non-malaria endemic travellers who, over a one-year period, consulted the French embassy’s Centre Médico-Social in Ouagadougou (Burkina Faso) for fever. All patients underwent a clinical examination, a questionnaire, and three different malaria tests: thick blood film, QBC-test and HRP-2-based rapid diagnostic test.

Results

Fever was caused by malaria in 69 cases (23%), while 37 (12%) were due to Pneumonia and 35 cases (8%) to ENT infections. Fever remained unexplained in 87 patients (51.3%). Malaria prevalence varied throughout the year: about 90% of malaria cases were diagnosed during and after the rainy season, between July and December, with up to 50% malaria prevalence for fever cases in October. Malaria diagnosis based solely on clinical signs, combined or not, leads to about 80% of unnecessary treatments.Although anti-malarial chemoprophylaxis was used in only 69% of short-stay patients (who travelled for less than three months), this was effective. Under local conditions, and using blood film examination as the reference method, the QBC test appeared to be more reliable than the HRP-2-based rapid diagnostic test, with respective sensitivities of 98.6% versus 84.1%, and specificities of 99.6% versus 98.3%.

Conclusions

Reliable biological diagnosis of malaria among travellers from non-malaria endemic countries in Sahelian areas is necessary because of low malaria prevalence and the poor performance of clinical diagnosis. A fever during the first half of the year requires investigating another aetiology, particularly a respiratory one. Malaria chemoprophylaxis is efficient and must not be overlooked. The QBC test appears to be the most reliable diagnostic test in this context.

Severity of imported malaria: protective effect of taking malaria chemoprophylaxis

Background

Although chemoprophylaxis remains an important strategy for preventing malaria in travellers, its effectiveness may be compromised by lack of adherence. Inappropriate use of chemoprophylaxis is likely to increase the risk of acquiring malaria, but may probably also worsen the severity of imported cases. The aim of this study was to assess the impact of use of malaria chemoprophylaxis on clinical features and outcome of imported malaria.

Methods

Demographic, clinical and laboratory data of patients included in the Rotterdam Malaria Cohort between 1998 and 2011 were systematically collected and analysed. Patients were classified as self-reported compliant or non-compliant users or as non-users of chemoprophylaxis. Severe malaria was defined using the 2010 WHO criteria.

Results

Details on chemoprophylaxis were available for 559 of the 604 patients, of which 64.6% were non-users, 17.9% were inadequate users and 17.5% reported to be adequate users. The group of non-users was predominated by patients with African ethnicity, partial immunity and people visiting friends and relatives. The majority contracted Plasmodium falciparum malaria. In contrast, compliant users acquired non-falciparum malaria more frequently, had significant lower P. falciparum loads on admission, shorter duration of hospitalization and significant lower odds for severe malaria as compared with non-users. Patients with P. falciparum malaria were more likely to have taken their chemoprophylaxis less compliantly than those infected with non-P. falciparum species. Multivariate analysis showed that self-reported adequate prophylaxis and being a partially immune traveller visiting friends and relatives was associated with significantly lower odds ratio of severe malaria. In contrast, age, acquisition of malaria in West-Africa and being a non-immune tourist increased their risk significantly.

Conclusions

Compliant use of malaria chemoprophylaxis was associated with significantly lower odds ratios for severe malaria as compared with non-compliant users and non-users of chemoprophylaxis. After correction for age, gender and immunity, this protective effect of malaria chemoprophylaxis was present only in individuals who adhered compliantly to use of chemoprophylaxis. Patients with P. falciparum malaria were more likely to have used their chemoprophylaxis less compliantly than patients with non-P. falciparum malaria who were more likely to have contracted malaria in spite of compliant use of chemoprophylaxis.

Current challenges in travelers' malaria

Travel health providers are often confronted with complex scenarios when advising travelers on malaria prevention. Current challenges in prevention include malaria risk assessment, where a detailed itinerary and knowledge of malaria epidemiology are needed. Up-to-date information on the correct use, limitations, and drug interactions of current priority chemoprophylaxis agents (atovaquone/proguanil, mefloquine, doxycycline) is key. Another challenge is to identify and reach travelers who are most at risk of malaria, such as the traveler visiting friends and relatives. Posttravel, delays in presentation, diagnosis, and inappropriate treatment of malaria are key risk factors leading to death. Treatment of malaria is an emergency requiring expert in-patient management and referral to a center with adequate expertise. Artemisinin combination therapies are the drugs of choice for uncomplicated malaria. Complicated malaria is treated preferably with intravenous artesunate, and the supply and quality of this life-saving antimalarial in some settings can pose one of the most urgent challenges in travelers' malaria.

GeoSentinel surveillance of illness in returned travelers, 2007-2011

BACKGROUND

International travel continues to increase, particularly to Asia and Africa. Clinicians are increasingly likely to be consulted for advice before travel or by ill returned travelers.

OBJECTIVE

To describe typical diseases in returned travelers according to region, travel reason, and patient demographic characteristics; describe the pattern of low-frequency travel-associated diseases; and refine key messages for care before and after travel.

DESIGN

Descriptive, using GeoSentinel records.

SETTING

53 tropical or travel disease units in 24 countries.

PATIENTS

42 173 ill returned travelers seen between 2007 and 2011.

MEASUREMENTS

Frequencies of demographic characteristics, regions visited, and illnesses reported.

RESULTS

Asia (32.6%) and sub-Saharan Africa (26.7%) were the most common regions where illnesses were acquired. Three quarters of travel-related illness was due to gastrointestinal (34.0%), febrile (23.3%), and dermatologic (19.5%) diseases. Only 40.5% of all ill travelers reported pretravel medical visits. The relative frequency of many diseases varied with both travel destination and reason for travel, with travelers visiting friends and relatives in their country of origin having both a disproportionately high burden of serious febrile illness and very low rates of advice before travel (18.3%). Life-threatening diseases, such as Plasmodium falciparum malaria, melioidosis, and African trypanosomiasis, were reported.

LIMITATIONS

Sentinel surveillance data collected by specialist clinics do not reflect healthy returning travelers or those with mild or self-limited illness. Data cannot be used to infer quantitative risk for illness.

CONCLUSION

Many illnesses may have been preventable with appropriate advice, chemoprophylaxis, or vaccination. Clinicians can use these 5-year GeoSentinel data to help tailor more efficient pretravel preparation strategies and evaluate possible differential diagnoses of ill returned travelers according to destination and reason for travel.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Artemisinin based combination therapy in travel medicine

A steadily increasing number of Western travellers are exposed to malaria. Also, numbers of migrants from malarious areas are increasing. Fast and effective treatment options are needed to ensure effective malaria treatment in these groups in the future. Artemisinin combinations are well tolerated and have shown high efficacy in malaria endemic areas. Since 2001, 42 malaria endemic countries, 23 of them in Africa, have adopted artemisinin based combination therapies recommended by WHO. An additional 14 countries are in the process of changing their malaria treatment policy. Studies in non-immune travellers confirm a rapid parasite clearance time and very low rate of side effects. Outpatient clinics and hospitals in non-endemic countries should have standard operating procedures for diagnosing and managing patients with malaria. In this setting, artemisinin combinations should be available for treatment of uncomplicated malaria as they are clearly superior to any other oral antimalarial in their fast reduction of parasite biomass and in decreasing clinical symptoms. Also, they are the drugs of choice for travellers who are advised to carry stand-by emergency treatment during their journey.

Management of imported malaria in Europe

In this position paper, the European Society for Clinical Microbiology and Infectious Diseases, Study Group on Clinical Parasitology, summarizes main issues regarding the management of imported malaria cases. Malaria is a rare diagnosis in Europe, but it is a medical emergency. A travel history is the key to suspecting malaria and is mandatory in patients with fever. There are no specific clinical signs or symptoms of malaria although fever is seen in almost all non-immune patients. Migrants from malaria endemic areas may have few symptoms.Malaria diagnostics should be performed immediately on suspicion of malaria and the gold- standard is microscopy of Giemsa-stained thick and thin blood films. A Rapid Diagnostic Test (RDT) may be used as an initial screening tool, but does not replace urgent microscopy which should be done in parallel. Delays in microscopy, however, should not lead to delayed initiation of appropriate treatment. Patients diagnosed with malaria should usually be hospitalized. If outpatient management is preferred, as is the practice in some European centres, patients must usually be followed closely (at least daily) until clinical and parasitological cure. Treatment of uncomplicated Plasmodium falciparum malaria is either with oral artemisinin combination therapy (ACT) or with the combination atovaquone/proguanil. Two forms of ACT are available in Europe: artemether/lumefantrine and dihydroartemisinin/piperaquine. ACT is also effective against Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium knowlesi, but these species can be treated with chloroquine. Treatment of persistent liver forms in P. vivax and P. ovale with primaquine is indicated after excluding glucose 6 phosphate dehydrogenase deficiency. There are modified schedules and drug options for the treatment of malaria in special patient groups, such as children and pregnant women. The potential for drug interactions and the role of food in the absorption of anti-malarials are important considerations in the choice of treatment.Complicated malaria is treated with intravenous artesunate resulting in a much more rapid decrease in parasite density compared to quinine. Patients treated with intravenous artesunate should be closely monitored for haemolysis for four weeks after treatment. There is a concern in some countries about the lack of artesunate produced according to Good Manufacturing Practice (GMP).

Malaria prevention in travelers

A common approach to malaria prevention is to follow the "A, B, C, D" rule: Awareness of risk, Bite avoidance, Compliance with chemoprophylaxis, and prompt Diagnosis in case of fever. The risk of acquiring malaria depends on the length and intensity of exposure; the risk of developing severe disease is primarily determined by the health status of the traveler. These parameters need to be assessed before recommending chemoprophylaxis and/or stand-by emergency treatment. This review discusses the different strategies and drug options available for the prevention of malaria during and post travel.

A highly sensitive aptasensor towards Plasmodium lactate dehydrogenase for the diagnosis of malaria

Finding a highly sensitive diagnostic technique for malaria has challenged scientists for the last century. In the present study, we identified versatile single-strand DNA aptamers for Plasmodium lactate dehydrogenase (pLDH), a biomarker for malaria, via the Systematic Evolution of Ligands by EXponential enrichment (SELEX). The pLDH aptamers selectively bound to the target proteins with high sensitivity (K(d)=16.8-49.6 nM). The selected aptamers were characterized using an electrophoretic mobility shift assay, a quartz crystal microbalance, a fluorescence assay, and circular dichroism spectroscopy. We also designed a simple aptasensor using electrochemical impedance spectroscopy; both Plasmodium vivax LDH and Plasmodium falciparum LDH were selectively detected with a detection limit of 1 pM. Furthermore, the pLDH aptasensor clearly distinguished between malaria-positive blood samples of two major species (P. vivax and P. falciparum) and a negative control, indicating that it may be a useful tool for the diagnosis, monitoring, and surveillance of malaria.

Review: Malaria chemoprophylaxis for travelers to Latin America

Because of recent declining malaria transmission in Latin America, some authorities have recommended against chemoprophylaxis for most travelers to this region. However, the predominant parasite species in Latin America, Plasmodium vivax, can form hypnozoites sequestered in the liver, causing malaria relapses. Additionally, new evidence shows the potential severity of vivax infections, warranting continued consideration of prophylaxis for travel to Latin America. Individualized travel risk assessments are recommended and should consider travel locations, type, length, and season, as well as probability of itinerary changes. Travel recommendations might include no precautions, mosquito avoidance only, or mosquito avoidance and chemoprophylaxis. There are a range of good options for chemoprophylaxis in Latin America, including atovaquone-proguanil, doxycycline, mefloquine, and--in selected areas--chloroquine. Primaquine should be strongly considered for nonpregnant, G6PD-nondeficient patients traveling to vivax-endemic areas of Latin America, and it has the added benefit of being the only drug to protect against malaria relapses.

Epidemiology of imported malaria among children and young adults in Barcelona (1990-2008)

Background

Increasing international travel and migration is producing changes in trends in infectious diseases, especially in children from many European cities. The objective of this study was to describe the epidemiology and determine the trends of imported malaria in patients under 20 years old in the city of Barcelona, Spain, during an 18-year period.

Methods

The study included malaria cases that were laboratory confirmed and reported to the malaria register at the Public Health Agency of Barcelona from 1990 to 2008, residing in Barcelona and less than 20 years old. Patients were classified as natives (born in Spain) or immigrants. Differences in the distribution of demographic, clinical characteristics, and incidence per 100,000 person-year evolution were analysed. Natives and immigrants were compared by logistic regression by calculating the odds ratio (OR) with a 95% confidence interval (CI) and Chi-square for a linear trend (p < 0.05).

Results

Of the total 174 cases, 143 (82.1%) were immigrants, 100 (57.5%) were female, 121 (69.5%) Plasmodium falciparum, and 108 (62.1%) were visiting friends and relatives (VFR) as the reason for travel. Among the immigrants, 99 (67.8%) were from Equatorial Guinea. Immigrant cases more frequently travelled to Africa than natives (p = 0.02). The factors associated with imported malaria among immigrant residents was travelling for VFR (OR: 6.2 CI 1.9-20.2) and age 15-19 (OR: 3.7 CI 1-13.3). The incidence increased from 1990 to 1999 (p < 0.001) and decreased from 2000 to 2008 (p = 0.01), although the global linear trend was not statistically significant (p = 0.41). The fatality rate was 0.5%.

Conclusions

The majority of cases of malaria in population less than 20 years in Barcelona were immigrants, travelling to Africa for VFR and Plasmodium falciparum was most frequently detected. The trend analysis of the entire study period did not show a statistically significant decline. It is recommended to be aware of malaria, especially among children of immigrants who travel to their parent's home country for VFR. Better access to pre travel advice should be provided.

The position of mefloquine as a 21st century malaria chemoprophylaxis

BACKGROUND

Malaria chemoprophylaxis prevents the occurrence of the symptoms of malaria. Travellers to high-risk Plasmodium falciparum endemic areas need an effective chemoprophylaxis.

METHODS

A literature search to update the status of mefloquine as a malaria chemoprophylaxis.

RESULTS

Except for clearly defined regions with multi-drug resistance, mefloquine is effective against the blood stages of all human malaria species, including the recently recognized fifth species, Plasmodium knowlesi. New data were found in the literature on the tolerability of mefloquine and the use of this medication by groups at high risk of malaria.

DISCUSSION

Use of mefloquine for pregnant women in the second and third trimester is sanctioned by the WHO and some authorities (CDC) allow the use of mefloquine even in the first trimester. Inadvertent pregnancy while using mefloquine is not considered grounds for pregnancy termination. Mefloquine chemoprophylaxis is allowed during breast-feeding. Studies show that mefloquine is a good option for other high-risk groups, such as long-term travellers, VFR travellers and families with small children. Despite a negative media perception, large pharmaco-epidemiological studies have shown that serious adverse events are rare. A recent US evaluation of serious events (hospitalization data) found no association between mefloquine prescriptions and serious adverse events across a wide range of outcomes including mental disorders and diseases of the nervous system. As part of an in-depth analysis of mefloquine tolerability, a potential trend for increased propensity for neuropsychiatric adverse events in women was identified in a number of published clinical studies. This trend is corroborated by several cohort studies that identified female sex and low body weight as risk factors.

CONCLUSION

The choice of anti-malarial drug should be an evidence-based decision that considers the profile of the individual traveller and the risk of malaria. Mefloquine is an important, first-line anti-malarial drug but it is crucial for prescribers to screen medical histories and inform mefloquine users of potential adverse events. Careful prescribing and observance of contraindications are essential. For some indications, there is currently no replacement for mefloquine available or in the pipeline.

Malaria: prevention in travellers

INTRODUCTION

Malaria transmission occurs most frequently in environments with humidity greater than 60% and ambient temperature of 25 °C to 30 °C. Risks increase with longer visits and depend on activity. Infection can follow a single mosquito bite. Incubation is usually 10 to 14 days but can be up to 18 months depending on the strain of parasite.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of non-drug preventive interventions in non-pregnant adult travellers? What are the effects of drug prophylaxis in non-pregnant adult travellers? What are the effects of antimalaria vaccines in adult and child travellers? What are the effects of antimalaria interventions in child travellers, pregnant travellers, and in airline pilots? We searched: Medline, Embase, The Cochrane Library, and other important databases up to November 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 79 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: aerosol insecticides, amodiaquine, air conditioning and electric fans, atovaquone-proguanil, biological control measures, chloroquine (alone or with proguanil), diethyltoluamide (DEET), dietary supplementation, doxycycline, electronic mosquito repellents, full-length and light-coloured clothing, insecticide-treated clothing/nets, mefloquine, mosquito coils and vapourising mats, primaquine, pyrimethamine-dapsone, pyrimethamine-sulfadoxine, smoke, topical (skin-applied) insect repellents, and vaccines.

Imported malaria in children: a comparative study between recent immigrants and immigrant travelers (VFRs)

BACKGROUND

In Europe, imported malarial cases occur in returning travelers and immigrants mostly from African countries. There have been an increasing number of cases in the past years in Spain.

METHODS

An analysis of all cases of malaria who attended at the Hospital of Mostoles in the Southwest of Madrid from 1995 to 2007 was performed. Clinical, epidemiological, laboratory, and parasitological findings were analyzed and compared between immigrants coming from endemic countries (recent immigrants) and children who traveled to endemic areas to visit friends and relatives (VFRs).

RESULTS

Sixty cases of imported malaria were detected. Most of the cases (59 of 60) were acquired in sub-Saharan Africa. The most common species was Plasmodium falciparum (43 of 60). Microscopic examination was positive in 95%, and the polymerase chain reaction (PCR) for Plasmodium achieved additional diagnosis in seven cases. Fourteen cases were VFRs; none of them used appropriate malaria chemoprophylaxis. Fever and thrombocytopenia were significantly more common among VFRs. They also had significantly higher parasite density. Twelve cases were asymptomatic at the time of diagnosis; all of them were recent immigrants.

CONCLUSIONS

VFRs account for a significant number of childhood malarial cases. These patients had not taken malaria chemoprophylaxis and malarial cases were more severe. VFR children are a high-risk group, and pretravel advice should underline the risk for malaria. Recent immigrants can be asymptomatic and parasitemias are lower. Therefore, a high index of suspicion is necessary, and PCR for Plasmodium should be performed in case of negative thick smears.

Imported methicillin-resistant Staphylococcus aureus, Sweden

Knowledge of different risks for infection will improve control measures.

Countries such as Sweden that have a low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) offer the opportunity to discern and study transmission of imported cases of MRSA. We analyzed 444 imported cases of MRSA acquisition reported in Sweden during 2000–2003. Risk for MRSA in returning travelers ranged from 0.1 (95% confidence interval [CI] 0.01–0.4) per 1 million travelers to Nordic countries to 59.4 (95% CI 44.5–79.3) per 1 million travelers to North Africa and the Middle East. Most imported cases (246, 55%) were healthcare acquired, but regions with the highest risk for MRSA in travelers showed a correlation with community acquisition (r = 0.81, p = 0.001). Characteristic differences in MRSA strains acquired were dependent on the region from which they originated and whether they were community or healthcare acquired. Knowledge of differences in transmission of MRSA may improve control measures against imported cases.

Determinants of compliance with malaria chemoprophylaxis among French soldiers during missions in inter-tropical Africa

Background

The effectiveness of malaria chemoprophylaxis is limited by the lack of compliance whose determinants are not well known.

Methods

The compliance with malaria chemoprophylaxis has been estimated and analysed by validated questionnaires administered before and after the short-term missions (about four months) in five tropical African countries of 2,093 French soldiers from 19 military companies involved in a prospective cohort study. "Correct compliance" was defined as "no missed doses" of daily drug intake during the entire mission and was analysed using multiple mixed-effect logistic regression model.

Results

The averaged prevalence rate of correct compliance was 46.2%, ranging from 9.6%to 76.6% according to the companies. Incorrect compliance was significantly associated with eveningness (p = 0.028), a medical history of clinical malaria (p < 0.001) and a perceived mosquito attractiveness inferior or superior to the others (p < 0.007). Correct compliance was significantly associated with the systematic use of protective measures against mosquito bites (p < 0.001), the type of military operations (combat vs. training activities, p < 0.001) and other individual factors (p < 0.05).

Conclusions

The identification of circumstances and profiles of persons at higher risk of lack of compliance would pave the way to specifically targeted strategies aimed to improve compliance with malaria chemoprophylaxis and, therefore, its effectiveness.

Modeling the risk of malaria for travelers to areas with stable malaria transmission

Background

Malaria is an important threat to travelers visiting endemic regions. The risk of acquiring malaria is complex and a number of factors including transmission intensity, duration of exposure, season of the year and use of chemoprophylaxis have to be taken into account estimating risk.

Materials and methods

A mathematical model was developed to estimate the risk of non-immune individual acquiring falciparum malaria when traveling to the Amazon region of Brazil. The risk of malaria infection to travelers was calculated as a function of duration of exposure and season of arrival.

Results

The results suggest significant variation of risk for non-immune travelers depending on arrival season, duration of the visit and transmission intensity. The calculated risk for visitors staying longer than 4 months during peak transmission was 0.5% per visit.

Conclusions

Risk estimates based on mathematical modeling based on accurate data can be a valuable tool in assessing risk/benefits and cost/benefits when deciding on the value of interventions for travelers to malaria endemic regions.

Risk for malaria in United States donors deferred for travel to malaria-endemic areas

BACKGROUND

Deferral for travel to malaria-endemic areas excludes many blood donors in the United States. Most transfusion-transmitted malaria is associated with lengthy residence in malaria-endemic areas rather than routine travel. This study compares the impact of existing deferral requirements to the risk that a presenting donor with malaria travel history harbors malaria parasites under current and hypothetical alternate regulations.

STUDY DESIGN AND METHODS

Deferred donors from six blood centers were sampled to estimate a national cohort of donors deferred annually for malaria travel to different geographic regions. Risk for malaria infection after travel to each region and distribution of incubation periods for each malaria species were estimated for US travelers. Region-specific travel risks were used to estimate the risk that a presenting blood donor with malaria travel might asymptomatically harbor malaria parasites at different intervals after return to the United States.

RESULTS

Travel to Africa presents risk for malaria infection greater than 1000 times that of travel to malaria-endemic parts of Mexico, yet Mexico accounts for more than 10 times as many deferred donors. Shortening the deferral period from 12 to 3 months for travelers to Mexico increases the risk of collecting a contaminated unit by only 1 unit per 57 years (sensitivity analysis, 1 every 29-114 years), at annual gain of more than 56,000 donations.

CONCLUSION

This study provides the first systematic appraisal of the US requirements for donor qualification regarding travel to malarial areas. Consideration should be given to relaxing the guidelines for travel to very-low-risk areas such as Mexico.

Drugs for preventing malaria in travellers

BACKGROUND

Malaria infects 10,000 to 30,000 international travellers each year. It can be prevented through anti-mosquito measures and drug prophylaxis. However, antimalaria drugs have adverse effects which are sometimes serious.

OBJECTIVES

To compare the effects of currently used antimalaria drugs when given as prophylaxis to non-immune adult and child travellers who are travelling to regions with Plasmodium falciparum resistance to chloroquine. Specifically, to assess the efficacy, safety, and tolerability of atovaquone-proguanil, doxycycline, and mefloquine compared to each other, and also when compared to chloroquine-proguanil and to primaquine.

SEARCH STRATEGY

In August 2009 we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2008, Issue 4), MEDLINE, EMBASE, LILACS, BIOSIS, mRCT, and reference lists. We handsearched conference proceedings and one specialist journal, and contacted researchers and drug companies. We searched PubMed for drug-related deaths.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials of any antimalaria drug regimen currently used by non-immune international travellers.

DATA COLLECTION AND ANALYSIS

We independently extracted data and assessed eligibility and risk of bias using a standardized data collection form. We resolved any disagreement through discussion. We combined dichotomous outcomes using risk ratio (RR) and continuous data using mean difference (MD), presenting both with 95% confidence intervals (CI).

MAIN RESULTS

Eight trials (4240 participants) met the inclusion criteria. Evidence on comparative efficacy from head-to-head comparisons was limited. Atovaquone-proguanil compared to doxycycline had similar adverse events reported. Compared to mefloquine, atovaquone-proguanil users had fewer reports of any adverse effect (RR 0.72, 95% CI 0.6 to 0.85), gastrointestinal adverse effects (RR 0.54, 95% CI 0.42 to 0.7), neuropsychiatric adverse events (RR 0.86, 95% CI 0.75 to 0.99), and neuropsychiatric adverse effects (RR 0.49, 95% CI 0.38 to 0.63), besides a better total mood disturbance score (MD -7.20, 95% CI -10.79 to -3.61). Similarly, doxycycline users had fewer reported neuropsychiatric events than mefloquine users (RR 0.84, 95% CI 0.73 to 0.96). We also examined these three regimens against chloroquine-proguanil; this latter regimen had more reports of any adverse effect (RR 0.84, 95% CI 0.73 to 0.96) and of gastrointestinal adverse effects (RR 0.71, 95% CI 0.6 to 0.85).

AUTHORS' CONCLUSIONS

Atovaquone-proguanil and doxycycline are the best tolerated regimens, and mefloquine is associated with adverse neuropsychiatric outcomes.