Malaria among United States troops in Somalia

Deployment Infectious Disease Threats: IDCRP Initiatives and Vision Forward

BACKGROUND

Infectious diseases pose a significant threat to health and readiness of military personnel deployed globally during wartime and peacekeeping activities. Surveillance and improvement in mitigation through research of infectious disease threats remain an integral part of Force Health Protection. Herein, we review research efforts of the Infectious Disease Clinical Research Program related to deployment and travel-related infections.

METHODS

The objectives of the Deployment and Travel-Related Infections Research Area are to (1) provide epidemiologic and clinical data, including pathogen-specific estimates of disease incidence among deployed troops, (2) execute clinical trials and effectiveness studies to improve recommendations regarding prevention and treatment of infections during deployment, and (3) evaluate the knowledge and practice patterns of health care providers engaged in deployment/travel medicine and the impact on outcomes. The centerpiece protocol of the research area is the Deployment and Travel-Related Infectious Disease Risk Assessment, Outcomes, and Prevention Strategies cohort study (TravMil), which was initiated in 2010 and collects data on a broad range of deployment-related infections.

RESULTS

To date, 4,154 deployed military personnel and traveling Department of Defense (DoD) beneficiaries have been enrolled in TravMil. Surveillance data collected through the TravMil study provide assessment of deployment and travel-related infectious disease threats, and the effectiveness of mitigation strategies. The incidence of travelers' diarrhea, influenza-like illness, and undifferentiated febrile illness is 20.48%, 9.34%, and 6.16%, respectively. The cohort study also provides necessary infrastructure to execute clinical trials. The TrEAT TD clinical trial evaluated the effectiveness of single-dose antibiotic therapy for travelers' diarrhea in the deployed setting. When compared to levofloxacin, azithromycin was not inferior; however, inferiority was not demonstrated with use of single dose of rifaximin. The trial findings supported the development of a deployment-related health guideline for the management of acute diarrheal disease. A clinical trial evaluating the effectiveness of rifaximin for prevention for travelers' diarrhea (Prevent TD) is underway.

CONCLUSIONS

The research area has proven its ability to conduct impactful research, including the development of field-expedient diagnostics, the largest DoD multi-site travelers' diarrhea randomized control trial in peacetime and combat settings, and informed Force Health Protection guidance. The research area continues to provide surveillance data to military commands via an established collaborative network of military treatment facilities, DoD laboratories (both within and outside the continental United States), foreign militaries, and academia. The conduct of clinical and translational research in a deployment setting presents significant challenges, most notably in recruitment/enrollment and compliance with study-related procedures during deployment.

Mefloquine for preventing malaria during travel to endemic areas

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Identification of a Syndrome Class of Neuropsychiatric Adverse Reactions to Mefloquine from Latent Class Modeling of FDA Adverse Event Reporting System Data

Introduction

Although mefloquine use is known to be associated with a risk of severe neuropsychiatric adverse reactions that are often preceded by prodromal symptoms, specific combinations of neurologic or psychiatric reactions associated with mefloquine use are not well described in the literature. This study sought to identify a distinct neuropsychiatric syndrome class associated with mefloquine use in reports of adverse events.

Methods

Latent class modeling of US Food and Drug Administration Adverse Event Reporting System (FAERS) data was performed using indicators defined by the Medical Dictionary for Regulatory Activities neurologic and psychiatric high-level group terms, in a study dataset of FAERS reports (n = 5332) of reactions to common antimalarial drugs.

Results

A distinct neuropsychiatric syndrome class was identified that was strongly and significantly associated with reports of mefloquine use (odds ratio = 3.92, 95% confidence interval 2.91–5.28), defined by a very high probability of symptoms of deliria (82.7%) including confusion and disorientation, and a moderate probability of other severe psychiatric and neurologic symptoms including dementia and amnesia (18.6%) and seizures (18.1%). The syndrome class was also associated with symptoms that are considered prodromal including anxiety, depression, sleep disturbance, and abnormal dreams, and neurological symptoms such as dizziness, vertigo, and paresthesias.

Conclusions

This study confirms in FAERS reports the existence of a severe mefloquine neuropsychiatric syndrome class associated with common symptoms that may be considered prodromal. Clinical identification of the characteristic symptoms of this syndrome class may aid in improving case finding in pharmacovigilance studies of more serious adverse reactions to the drug.

Prophylactic efficacy of primaquine for preventing Plasmodium falciparum and Plasmodium vivax parasitaemia in travelers: A meta-analysis and systematic review

BACKGROUND

With increased international travel over the world the need for safe and effective chemoprophylaxis for malaria is as great as ever. The choice of regimen is difficult, as effectiveness should be weighted against potential adverse effects. Although, some studies have reported high prophylactic efficacy of primaquine, there is no comprehensive evidence comparing its prophylactic effectiveness as well as toxicity. To fill the gap, this systematic review and meta-analysis study was carried out.

METHODS

Using MeSH terms, 756 records were detected through searching "Pubmed", "Embase","Web of Science"and "Cochrane" databases. From these,7 relevant full-text articles with 14 comparisons for final quantitative meta-analysis were included in our review. In order to make a comparison between the studies, Risk Ratios(RRs) and their 95% confidence intervals(CIs) were estimated.

RESULTS

Overall,74% reduction in the incidence of parasitaemia by primaquine versus other prophylactic regimens was estimated(RRoverall = 0.26, CI 95%:0.16-0.41--RRvivax = 0.16, CI 95%:0.07-0.36--RRfalciparum = 0.31, CI 95%:0.18-0.55). The incidence rate ratios for adverse effects showed no statistically significant difference between primaquine and control groups (p > 0.05).

CONCLUSIONS

For persons without G6PD deficiency, who are not pregnant, primaquine is the most effective presently available prophylactic for P. vivax malaria and comparable to such regimens as doxycycline, mefloquine and atovaquone-proguanil for the prevention of P. falciparum malaria.

Psychiatric effects of malaria and anti-malarial drugs: historical and modern perspectives

The modern medical literature implicates malaria, and particularly the potentially fatal form of cerebral malaria, with a risk of neurocognitive impairment. Yet historically, even milder forms of malaria were associated in the literature with a broad range of psychiatric effects, including disorders of personality, mood, memory, attention, thought, and behaviour. In this article, the history of psychiatric effects attributed to malaria and post-malaria syndromes is reviewed, and insights from the historical practice of malariotherapy in contributing to understanding of these effects are considered. This review concludes with a discussion of the potentially confounding role of the adverse effects of anti-malarial drugs, particularly of the quinoline class, in the unique attribution of certain psychiatric effects to malaria, and of the need for a critical reevaluation of the literature in light of emerging evidence of the chronic nature of these adverse drug effects.

Malaria in the Traveler: How to Manage Before Departure and Evaluate Upon Return

Malaria is the clinical syndrome when a patient experiences symptoms in response to infection with one of several strains of the Plasmodium parasite. This article is intended for health care providers to become familiar with some of the basics of care of patients who are travelling to or returning from an area with ongoing malaria transmission. The specific focus is on patients from nonendemic areas who plan on travel for a finite period to an area where malaria is endemic.

Tetracyclines in malaria

Malaria, a parasite vector-borne disease, is one of the greatest health threats in tropical regions, despite the availability of malaria chemoprophylaxis. The emergence and rapid extension of Plasmodium falciparum resistance to various anti-malarial drugs has gradually limited the number of potential malaria therapeutics available to clinicians. In this context, doxycycline, a synthetically derived tetracycline, constitutes an interesting alternative for malaria treatment and prophylaxis. Doxycycline is a slow-acting blood schizontocidal agent that is highly effective at preventing malaria. In areas with chloroquine and multidrug-resistant P. falciparum parasites, doxycycline has already been successfully used in combination with quinine to treat malaria, and it has been proven to be effective and well-tolerated. Although not recommended for pregnant women and children younger than 8 years of age, severe adverse effects are rarely reported. In addition, resistance to doxycycline is rarely described. Prophylactic and clinical failures of doxycycline have been associated with both inadequate doses and poor patient compliance. The effects of tetracyclines on parasites are not completely understood. A better comprehension of the mechanisms underlying drug resistance would facilitate the identification of molecular markers of resistance to predict and survey the emergence of resistance.

Absence of association between Plasmodium falciparum small sub-unit ribosomal RNA gene mutations and in vitro decreased susceptibility to doxycycline

Background

Doxycycline is an antibiotic used in combination with quinine or artesunate for malaria treatment or alone for malaria chemoprophylaxis. Recently, one prophylactic failure has been reported, and several studies have highlighted in vitro doxycycline decreased susceptibility in Plasmodium falciparum isolates from different areas. The genetic markers that contribute to detecting and monitoring the susceptibility of P. falciparum to doxycycline, the pfmdt and pftetQ genes, have recently been identified. However, these markers are not sufficient to explain in vitro decreased susceptibility of P. falciparum to doxycycline. In this paper, the association between polymorphism of the small sub-unit ribosomal RNA apicoplastic gene pfssrRNA (PFC10_API0057) and in vitro susceptibilities of P. falciparum isolates to doxycycline were investigated.

Methods

Doxycycline IC₅₀ determinations using the hypoxanthine uptake inhibition assay were performed on 178 African and Thai P. falciparum isolates. The polymorphism of pfssrRNA was investigated in these samples by standard PCR followed by sequencing.

Results

No point mutations were found in pfssrRNA in the Thai or African isolates, regardless of the determined IC₅₀ values.

Conclusions

The pfssrRNA gene is not associated with in vitro decreased susceptibility of P. falciparum to doxycycline. Identifying new in vitro molecular markers associated with reduced susceptibility is needed, to survey the emergence of doxycycline resistance.

Safety, Tolerability, and Compliance with Long-Term Antimalarial Chemoprophylaxis in American Soldiers in Afghanistan

Long-term antimalarial chemoprophylaxis is currently used by deployed U.S. military personnel. Previous small, short-term efficacy studies have shown variable rates of side effects among patients taking various forms of chemoprophylaxis, though reliable safety and tolerability data on long-term use are limited. We conducted a survey of troops returning to Fort Drum, NY following a 12-month deployment to Operation Enduring Freedom, Afghanistan from 2006 to 2007. Of the 2,351 respondents, 95% reported taking at least one form of prophylaxis during their deployment, and 90% were deployed for > 10 months. Compliance with daily doxycycline was poor (60%) compared with 80% with weekly mefloquine (MQ). Adverse events (AEs) were reported by approximately 30% with both MQ and doxycycline, with 10% discontinuing doxycycline compared with 4% of MQ users. Only 6% and 31% of soldiers reported use of bed nets and skin repellents, respectively. Compliance with long-term malaria prophylaxis was poor, and there were substantial tolerability issues based on these anonymous survey results, though fewer with MQ than doxycycline. Given few long-term antimalarial chemoprophylaxis options, there is an unmet medical need for new antimalarials safe for long-term use.

A literature review of medical aspects of post-cold war UN peacekeeping operations: trends, lessons learnt, courses of action and recommendations

OBJECTIVE

Post-Cold War United Nations Peace Keeping Operations (UN PKOs) have been increasingly involved in dangerous areas with ill-defined boundaries, harsh and remote geographies, simmering internecine armed conflict and disregard on the part of some local parties for peacekeepers' security and role. In the interest of 'force protection' and optimising operations, a key component of UN PKOs is healthcare and medical treatment. The expectation is that UN PKO medical support will conform to the general intent and structure of UN PKOs. To do so requires effective policies and planning informed by a review of medical aspects crucial to UN PKOs. The intent of this article is to report on a review of principal medical aspects practical to post-Cold War UN PKOs.

METHODS

This review was assembled through a comprehensive, grounded, systematic iterative inquiry of open-source articles.

RESULTS

This inquiry revealed that the principal medical aspects in post-Cold War UN missions were the following: (1) the changed nature of UN PKOs, (2) new challenges in terms of proximity and distance to medical care, (3) expanded need for preventive medicine and disease contagion prevention and (4) increased propensity for psychological morbidity and need for intervention.

CONCLUSIONS

Post Cold War, the dramatically changed nature of UN PKOs has resulted in new challenges mainly in terms of medical logistics, preventive medicine and psychiatry. The changed nature of post-Cold War UN PKOs altered the character of medical support most notably regarding (1) a need for emphasis on immediate response proximate to medical events and rapid transport over long distances and traversing barriers to higher levels of care, (2) proactive contagion and hazard identification and prevention and (3) interventions designed to reduce psychological morbidity. Recommendations are offered about possible courses of action in terms of addressing trends found in identified medical aspects of PKOs.

Reduced in vitro doxycycline susceptibility in plasmodium falciparum field isolates from Kenya is associated with PfTetQ KYNNNN sequence polymorphism

Doxycycline is widely used for malaria prophylaxis by international travelers. However, there is limited information on doxycycline efficacy in Kenya, and genetic polymorphisms associated with reduced efficacy are not well defined. In vitro doxycycline susceptibility profiles for 96 Plasmodium falciparum field isolates from Kenya were determined. Genetic polymorphisms were assessed in P. falciparum metabolite drug transporter (Pfmdt) and P. falciparum GTPase tetQ (PftetQ) genes. Copy number variation of the gene and the number of KYNNNN amino acid motif repeats within the protein encoded by PftetQ were determined. Reduced in vitro susceptibility to doxycycline was defined by 50% inhibitory concentrations (IC50s) of ≥35,000 nM. The odds ratio (OR) of having 2 PfTetQ KYNNNN amino acid repeats in isolates with IC50s of >35,000 nM relative to those with IC50s of <35,000 nM is 15 (95% confidence interval [CI], 3.0 to 74.3; P value of <0.0002). Isolates with 1 copy of the Pfmdt gene had a median IC50 of 6,971 nM, whereas those with a Pfmdt copy number of >1 had a median IC50 of 9,912 nM (P = 0.0245). Isolates with 1 copy of PftetQ had a median IC50 of 6,370 nM, whereas isolates with a PftetQ copy number of >1 had a median IC50 of 3,422 nM (P < 0.0007). Isolates with 2 PfTetQ KYNNNN motif repeats had a median IC50 of 26,165 nM, whereas isolates with 3 PfTetQ KYNNNN repeats had a median IC50 of 3,352 nM (P = 0.0023). PfTetQ sequence polymorphism is associated with a reduced doxycycline susceptibility phenotype in Kenyan isolates and is a potential marker for susceptibility testing.

Emerging and re-emerging infectious diseases: challenges and opportunities for militaries

The communal nature of living and training environments, alongside suboptimal hygiene and stressors in the field, place military personnel at higher risk of contracting emerging infectious diseases. Some of these diseases spread quickly within ranks resulting in large outbreaks, and personnel deployed are also often immunologically naïve to otherwise uncommonly-encountered pathogens. Furthermore, the chance of weaponised biological agents being used in conventional warfare or otherwise remains a very real, albeit often veiled, threat. However, such challenges also provide opportunities for the advancement of preventive and therapeutic military medicine, some of which have been later adopted in civilian settings. Some of these include improved surveillance, new vaccines and drugs, better public health interventions and inter-agency co-operations. The legacy of successes in dealing with infectious diseases is a reminder of the importance in sustaining efforts aimed at ensuring a safer environment for both military and the community at large.

PftetQ and pfmdt copy numbers as predictive molecular markers of decreased ex vivo doxycycline susceptibility in imported Plasmodium falciparum malaria

Background

The objective of this study was to evaluate the distribution of a series of independent doxycycline inhibitory concentration 50% (IC₅₀) values to validate the trimodal distribution previously described and to validate the use of the pftetQ and pfmdt genes as molecular markers of decreased in vitro doxycycline susceptibility in Plasmodium falciparum malaria.

Methods

Doxycycline IC₅₀ values, from 484 isolates obtained at the French National Reference Centre for Imported Malaria (Paris) between January 2006 and December 2010, were analysed for the first time by a Bayesian mixture modelling approach to distinguish the different in vitro phenotypic groups by their IC₅₀ values. Quantitative real-time polymerase chain reaction was used to evaluate the pftetQ and pfmdt copy numbers of 89 African P. falciparum isolates that were randomly chosen from the phenotypic groups.

Results

The existence of at least three doxycycline phenotypes was demonstrated. The mean doxycycline IC₅₀ was significantly higher in the group with a pftetQ copy number >1 compared to the group with a pftetQ copy number = 1 (33.17 μM versus 17.23 μM) and the group with a pfmdt copy number >1 (28.28 μM versus 16.11 μM). There was a significant difference between the combined low and medium doxycycline IC₅₀ group and the high IC₅₀ group in terms of the per cent of isolates with one or more copy numbers of the pftetQ gene (0% versus 20.69%) or pfmdt gene (8.33% versus 37.93%). In the logistic regression model, the pfmdt and pftetQ copy numbers >1 (odds ratio = 4.65 and 11.47) were independently associated with the high IC₅₀ group.

Conclusions

Copy numbers of pftetQ and pfmdt are potential predictive molecular markers of decreased susceptibility to doxycycline.

Mass administration of the antimalarial drug mefloquine to Guantánamo detainees: a critical analysis

Recently, evidence has emerged from an unusual form of mass drug administration practised among detainees held at US Naval Station Guantánamo Bay, Cuba ('Guantánamo'), ostensibly as a public health measure. Mefloquine, an antimalarial drug originally developed by the US military, whose use is associated with a range of severe neuropsychiatric adverse effects, was administered at treatment doses to detainees immediately upon their arrival at Guantánamo, prior to laboratory testing for malaria and irrespective of symptoms of disease. In this analysis, the history of mefloquine's development is reviewed and the indications for its administration at treatment doses are discussed. The stated rationale for the use of mefloquine among Guantánamo detainees is then evaluated in the context of accepted forms of population-based malaria control. It is concluded that there was no plausible public health indication for the use of mefloquine at Guantánamo and that based on prevailing standards of care, the clinical indications for its use are decidedly unclear. This analysis suggests the troubling possibility that the use of mefloquine at Guantánamo may have been motivated in part by knowledge of the drug's adverse effects, and points to a critical need for further investigation to resolve unanswered questions regarding the drug's potentially inappropriate use.

Absence of association between ex vivo susceptibility to doxycycline and pftetQ and pfmdt copy numbers in Plasmodium falciparum isolates from Dakar, Senegal

The objective of this study was to validate the use of pftetQ and pfmdt genes as molecular markers of decreased in vitro susceptibility to doxycycline in 113 Plasmodium falciparum isolates from Dakar, Senegal. The results show that copy numbers of pftetQ and pfmdt, estimated by TaqMan real-time PCR, are not significantly associated with reduced susceptibility to doxycycline in vitro; however, the number of samples with a high doxycycline IC(50) was likely to be too low to derive statistically significant results. Thus, no definitive conclusions could be drawn. The markers should be further tested by analysing more isolates.

Malaria in the Republic of Djibouti, 1998-2009

Historically, native populations in the Republic of Djibouti have experienced only low and unstable malaria transmission and intermittent epidemics. In recent years, efforts at malaria control have been aggressively pursued. This study was performed to inform revised malaria prevention recommendations for military service members and international travelers to the country. Laboratory-confirmed cases of malaria documented at large medical facilities and within military and civilian health care systems in the Republic of Djibouti from 1998 to 2009 were reviewed. In recent years, fewer than 5% of febrile cases among the three largest passive surveillance systems were laboratory-confirmed as malaria, and incidence of confirmed malaria was well below 1/1,000 persons/year. As efforts in the Republic of Djibouti progress toward elimination, and in conjunction with continued efforts at surveillance, emphasizing mosquito-avoidance measures and standby emergency treatment will become reasonable recommendations for malaria prevention.

Doxycycline for malaria chemoprophylaxis and treatment: report from the CDC expert meeting on malaria chemoprophylaxis

Doxycycline, a synthetically derived tetracycline, is a partially efficacious causal prophylactic (liver stage of Plasmodium) drug and a slow acting blood schizontocidal agent highly effective for the prevention of malaria. When used in conjunction with a fast acting schizontocidal agent, it is also highly effective for malaria treatment. Doxycycline is especially useful as a prophylaxis in areas with chloroquine and multidrug-resistant Plasmodium falciparum malaria. Although not recommended for pregnant women and children < 8 years of age, severe adverse events are rarely reported for doxycycline. This report examines the evidence behind current recommendations for the use of doxycycline for malaria and summarizes the available literature on its safety and tolerability.

Neurological disorders in complex humanitarian emergencies and natural disasters

Complex humanitarian emergencies include the relatively acute, severe, and overwhelming health consequences of armed conflict, food scarcity, mass displacement, and political strife. Neurological manifestations of complex humanitarian emergencies are important and underappreciated consequences of emergencies in populations worldwide. This review critically assesses the existing knowledge of the range of neurological disorders that accompany complex humanitarian emergencies and natural disasters in both the acute phase of crisis and the "long shadow" that follows.

An outbreak of Plasmodium falciparum malaria in U.S. Marines deployed to Liberia

In 2003, 44 U.S. Marines were evacuated from Liberia with either confirmed or presumed Plasmodium falciparum malaria. An outbreak investigation showed that only 19 (45%) used insect repellent, 5 (12%) used permethrin-treated clothing, and none used bed netting. Adherence with weekly mefloquine (MQ) was reported by 23 (55%). However, only 4 (10%) had serum MQ levels high enough to correlate with protection (> 794 ng/mL), and 9 (22%) had evidence of steady-state kinetics (MQ carboxy metabolite/MQ > 3.79). Tablets collected from Marines met USP identity and dissolution specifications for MQ. Testing failed to identify P. falciparum isolates with MQ resistance. This outbreak resulted from under use of personal protective measures and inadequate adherence with chemophrophylaxis. It is essential that all international travelers make malaria prevention measures a priority, especially when embarking to regions of the world with high transmission intensity such as west Africa..

The past and present threat of vector-borne diseases in deployed troops

From time immemorial, vector-borne diseases have severely reduced the fighting capacity of armies and caused suspension or cancellation of military operations. Since World War I, infectious diseases have no longer been the main causes of morbidity and mortality among soldiers. However, most recent conflicts involving Western armies have occurred overseas, increasing the risk of vector-borne disease for the soldiers and for the displaced populations. The threat of vector-borne disease has changed with the progress in hygiene and disease control within the military: some diseases have lost their military significance (e.g. plague, yellow fever, and epidemic typhus); others remain of concern (e.g. malaria and dengue fever); and new potential threats have appeared (e.g. West Nile encephalitis and chikungunya fever). For this reason, vector control and personal protection strategies are always major requirements in ensuring the operational readiness of armed forces. Scientific progress has allowed a reduction in the impact of arthropod-borne diseases on military forces, but the threat is always present, and a failure in the context of vector control or in the application of personal protection measures could allow these diseases to have the same devastating impact on human health and military readiness as they did in the past.

Doxycycline-chloroquine vs. doxycycline-placebo for malaria prophylaxis in nonimmune soldiers: a double-blind randomized field trial in sub-Saharan Africa

Failures of malaria chemoprophylaxis have been related to a lack of compliance with doxycycline due to its short elimination half-life. Adding a molecule with a long half-life to doxycycline could be useful to take over from this drug in case of occasional missed doses. A double-blind, placebo-controlled randomized field trial was designed to compare the tolerability of a doxycycline-chloroquine combination vs. doxycycline as malaria prophylaxis among French soldiers deployed in Africa. Data from 936 volunteers were analyzed. In both groups, the proportion of volunteers who reported at least one adverse effect was about 57%. Tolerability was similar in the groups except for a higher proportion of nausea or vomiting in the doxycycline-chloroquine group. The reported compliance rate was 86.6% and was similar in the two groups. Eight Plasmodium falciparum malaria cases were diagnosed in the doxycycline group and seven in the doxycycline-chloroquine group. The efficacy of the two chemoprophylaxis regimens was similar. Our study was the first randomized field trial to assess a doxycycline-chloroquine combination as malaria prophylaxis and showed no significant decrease of overall tolerability of the combination compared with doxycycline alone. Our results showed that a doxycycline-chloroquine combination could be a safe combination for malaria chemoprophylaxis.

The role of the United States military in the development of vector control products, including insect repellents, insecticides, and bed nets

Arthropod-borne diseases such as malaria, dengue, scrub typhus, and leishmaniasis continue to pose a significant threat to U.S. military forces deployed in support of operational and humanitarian missions. These diseases are transmitted by a variety of arthropods, including mosquitoes, ticks, chiggers, sand flies, and biting midges. In addition to disease threats, biting arthropods can cause dermatitis, allergic reactions, and sleep loss; therefore, monitoring of vector impact and integrated use of personal protective measures (PPM) and methods to reduce the vector populations are needed to protect service members. The U.S. military has played a vital role in vector identification tools and the development and testing of many of the most effective PPM and vector control products available today, including the topical repellent DEET and the repellent/insecticide permethrin, which is applied to clothing and bed nets. Efforts to develop superior products are ongoing. Although the U.S. military often needs vector control products with rather specific properties (e.g., undetectable, long-lasting in multiple climates) in order to protect its service members, many Department of Defense vector control products have had global impacts on endemic disease control.

Multinormal in vitro distribution model suitable for the distribution of Plasmodium falciparum chemosusceptibility to doxycycline

The distribution and range of 50% inhibitory concentrations (IC(50)s) of doxycycline were determined for 747 isolates obtained between 1997 and 2006 from patients living in Senegal, Republic of the Congo, and Gabon and patients hospitalized in France for imported malaria. The statistical analysis was designed to answer the specific question of whether Plasmodium falciparum has different phenotypes of susceptibility to doxycycline. A triple normal distribution was fitted to the data using a Bayesian mixture modeling approach. The IC(50) geometric mean ranged from 6.2 microM to 11.1 microM according to the geographical origin, with a mean of 9.3 microM for all 747 parasites. The values for all 747 isolates were classified into three components: component A, with an IC(50) mean of 4.9 microM (+/-2.1 microM [standard deviation]); component B, with an IC(50) mean of 7.7 microM (+/-1.2 microM); and component C, with an IC(50) mean of 17.9 microM (+/-1.4 microM). According to the origin of the P. falciparum isolates, the triple normal distribution was found in each subgroup. However, the proportion of isolates predicted to belong to component B was most important in isolates from Gabon and Congo and in isolates imported from Africa (from 46 to 56%). In Senegal, 55% of the P. falciparum isolates were predicted to be classified as component C. The cutoff of reduced susceptibility to doxycycline in vitro was estimated to be 35 microM.

Risk assessments for exposure of deployed military personnel to insecticides and personal protective measures used for disease-vector management

Infectious diseases are problematic for deployed military forces throughout the world, and, historically, more military service days have been lost to insect-vectored diseases than to combat. Because of the limitations in efficacy and availability of both vaccines and therapeutic drugs, vector management often is the best tool that military personnel have against most vector-borne pathogens. However, the use of insecticides may raise concerns about the safety of their effects on the health of the military personnel exposed to them. Therefore, our objective was to use risk assessment methodologies to evaluate health risks to deployed U.S. military personnel from vector management tactics. Our conservative tier-1, quantitative risk assessment focused on acute, subchronic, and chronic exposures and cancer risks to military personnel after insecticide application and use of personal protective measures in different scenarios. Exposures were estimated for every scenario, chemical, and pathway. Acute, subchronic, and chronic risks were assessed using a margin of exposure (MOE) approach. Our MOE was the ratio of a no-observed-adverse-effect level (NOAEL) to an estimated exposure. MOEs were greater than the levels of concern (LOCs) for all surface residual and indoor space spraying exposures, except acute dermal exposure to lambda-cyhalothrin. MOEs were greater than the LOCs for all chemicals in the truck-mounted ultra-low-volume (ULV) exposure scenario. The aggregate cancer risk for permethrin exceeded 1 x 10(-6), but more realistic exposure refinements would reduce the cancer risk below that value. Overall, results indicate that health risks from exposures to insecticides and personal protective measures used by military personnel are low.

Travel Recommendations for Older Adults

Older age is an important factor in preparing travelers owing not only to physiologic changes and the increased probability of underlying medical conditions and prescription medications but also to immune status with regard to naturally acquired immunity versus immunization for vaccine-preventable diseases. Cardiovascular events (including myocardial infarctions and cerebrovascular accidents) account for most deaths abroad, followed by injuries. To plan for healthy travel, international travelers should be advised to seek care at least 4 to 6 weeks before departure. Travel medicine is a dynamic field because conditions worldwide are subject to rapid change. Clinicians must maintain a current base of knowledge if they will be regularly advising travelers or must set a threshold for referral to a travel medicine specialist.

Surgical Support for Low-Intensity Conflict, Limited Warfare, and Special Operations

Low-intensity conflicts and special operations present a wide range of injury scenarios for military and civilian surgeons alike. Harsh environments, difficult and high-risk missions, long lines of communication, and isolated locations are but some of the factors that create challenge in providing care for patients in this category. Often surgeons and other medical personnel are faced with many additional medical and nonmedical tasks outside their usual expertise because of the small number of support personnel and medical footprints brought forward in these missions.

Role of US military research programs in the development of US Food and Drug Administration--approved antimalarial drugs

US military physicians and researchers helped identify the optimum treatment dose of the naturally occurring compound quinine and collaborated with the pharmaceutical industry in the development and eventual US Food and Drug Administration approval of the synthetic antimalarial drugs chloroquine, primaquine, chloroquine-primaquine, sulfadoxine-pyrimethamine, mefloquine, doxycycline, halofantrine, and atovaquone-proguanil. Because malaria parasites develop drug resistance, the US military must continue to support the creation and testing of new drugs to prevent and treat malaria until an effective malaria vaccine is developed. New antimalarial drugs also benefit civilians residing in and traveling to malarious areas.

Antimalarial activities of new pyrrolo[3,2-f]quinazoline-1,3-diamine derivatives

WR227825 is an antimalarial pyrroloquinazolinediamine derivative with a high potency but a low therapeutic index. A series of carbamate, carboxamide, succinimide, and alkylamine derivatives of WR227825 were prepared to search for compounds with an improved therapeutic index. The new acetamides and imide showed potent cell growth inhibition against four clones of Plasmodium falciparum (D-6, RCS, W-2, and TM91C235), with a 50% inhibitory concentration of approximately 0.01 ng/ml, and were highly active against Plasmodium berghei, with 100% cure at doses from <0.1 mg/kg of body weight to 220 mg/kg. The carbamates and alkyl derivatives, however, showed weak activity against Plasmodium falciparum cell growth but were highly efficacious in tests against P. berghei by the Thompson test. The best compounds, bis-ethylcarbamate (compound 2a) and tetra-acetamide (3a) derivatives, further demonstrated high potency against the sporozoite Plasmodium yoelii in mice and P. falciparum and Plasmodium vivax in aotus monkeys. Against the AMRU-1 strain of P. vivax, which has four dihydrofolate reductase mutations and is highly resistant to antifolates, tetra-acetamide 3a cured the monkeys at doses of 1 and 3 mg/kg. Compound 2a cured only one out of two monkeys at 3 mg/kg. The results indicated that the new derivatives 2a and 3a not only have retained/improved the antimalarial efficacy of the parent compound WR227825 but also were less toxic to the animals used in the tests.

Gastroenteritis in US Marines during Operation Iraqi Freedom

BACKGROUND

Approximately 83,000 US Marines participated in the opening phase of Operation Iraqi Freedom in Spring 2003. A Navy Preventive Medicine laboratory was set up in Ad Diwaniyah, Iraq, to provide clinical diagnostic support for Marine medical units during a period of repositioning in south-central Iraq.

METHODS

Specimen collection boxes were sent to >30 primary care medical stations handling 500-900 personnel each. The laboratory had capability to detect many different disease agents, especially those causing febrile illness. Diarrheal stool diagnostic evaluation included plating and biochemical identification, antigen serologic testing, fluorescent antibody antigen detection, disk diffusion antimicrobial susceptibility testing, enzyme immunoassay, and reverse-transcriptase polymerase chain reaction for norovirus (NV). Confirmation and sequencing work for NV was done at Cincinnati Children's Hospital Medical Center (Ohio).

RESULTS

By far the most common reason for infectious disease sick call visits was gastrointestinal illness; no other symptoms had equivalent impact. An enteropathogen was detected in 57 (44%) of 129 stool samples, with NV detected in 30 stool samples (23%) obtained from 14 different battalion or similar-sized units; next in frequency were Shigella flexneri and Shigella sonnei, which were isolated from 26 stool samples (20%) obtained from 15 units. Sequencing the NV RNA polymerase gene demonstrated that NV strains represented 7 genetic clusters, including 2 strains from genogroup I and 5 from genogroup II. Ciprofloxacin was effective in vitro against most bacterial agents, but neither doxycyline (which was taken daily as the antimalarial prophylaxis dose) nor trimethoprim-sulfamethoxazole were effective.

CONCLUSIONS

Multiple strains of Shigella species and NV predominated, probably because they do not require a large inoculum to cause infection. Otherwise, personnel remained free of infectious illness during this phase of the conflict, because other infectious agents were rare or absent.

Tolerability of malaria chemoprophylaxis in non-immune travellers to sub-Saharan Africa: multicentre, randomised, double blind, four arm study

OBJECTIVE

To compare the tolerability of malaria chemoprophylaxis regimens in non-immune travellers.

DESIGN

Randomised, double blind, study with placebo run-in phase.

SETTING

Travel clinics in Switzerland, Germany, and Israel.

MAIN OUTCOME MEASURE

Proportion of participants in each treatment arm with subjectively moderate or severe adverse events.

PARTICIPANTS

623 non-immune travellers to sub-Saharan Africa: 153 each received either doxycycline, mefloquine, or the fixed combination chloroquine and proguanil, and 164 received the fixed combination atovaquone and proguanil.

RESULTS

A high proportion of patients reported adverse events, even in the initial placebo group. No events were serious. The chloroquine and proguanil arm had the highest proportion of mild to moderate adverse events (69/153; 45%, 95% confidence interval 37% to 53%), followed by mefloquine (64/153; 42%, 34% to 50%), doxycycline (51/153; 33%, 26% to 41%), and atovaquone and proguanil (53/164; 32%, 25% to 40%) (P = 0.048 for all). The mefloquine and combined chloroquine and proguanil arms had the highest proportion of more severe events (n = 19; 12%, 7% to 18% and n = 16; 11%, 6% to 15%, respectively), whereas the combined atovaquone and proguanil and doxycycline arms had the lowest (n = 11; 7%, 2% to 11% and n = 9; 6%, 2% to 10%, respectively: P = 0.137 for all). The mefloquine arm had the highest proportion of moderate to severe neuropsychological adverse events, particularly in women (n = 56; 37%, 29% to 44% versus chloroquine and proguanil, n = 46; 30%, 23% to 37%; doxycycline, n = 36; 24%, 17% to 30%; and atovaquone and proguanil, n = 32; 20%, 13% to 26%: P = 0.003 for all). The highest proportion of moderate or severe skin problems were reported in the chloroquine and proguanil arm (n = 12; 8%, 4% to 13% versus doxycycline, n = 5; 3%, 1% to 6%; atovaquone and proguanil, n = 4; 2%, 0% to 5%; mefloquine, n = 2; 1%, 0% to 3%: P = 0.013).

CONCLUSIONS

Combined atovaquone and proguanil and doxycyline are well tolerated antimalarial drugs. Broader experience with both agents is needed to accumulate reports of rare adverse events.

Delayed onset of malaria--implications for chemoprophylaxis in travelers

BACKGROUND

Most antimalarial agents used by travelers act on the parasite's blood stage and therefore do not prevent late-onset illness, particularly that due to species that cause relapsing malaria. We examined the magnitude of this problem among Israeli and American travelers.

METHODS

We examined malaria surveillance data from Israel and the United States to determine the traveler's destination, the infecting species, the type of chemoprophylaxis used, and the incubation period.

RESULTS

In Israel, from 1994 through 1999, there were 300 cases of malaria among returning travelers in which one species of plasmodium could be identified. In 134 of these cases (44.7 percent), the illness developed more than two months after the traveler's return; nearly all of these cases were due to infection with Plasmodium vivax or P. ovale. In 108 of the 134 cases (80.6 percent), the patient had used an antimalarial regimen according to national guidelines. In the United States, from 1992 through 1998, there were 2822 cases of malaria among travelers in which the cause could be evaluated. Late illness developed in 987 (35.0 percent) of these travelers. The infection was due to P. vivax in 811 travelers, P. ovale in 66, P. falciparum in 59, and P. malariae in 51; 614 (62.2 percent) of those with late-onset illness had appropriately taken an effective antimalarial agent.

CONCLUSIONS

In more than one third of malaria-infected travelers, the illness developed more than two months after their return. Most of these late-onset illnesses are not prevented by the commonly used and effective blood schizonticides. Agents that act on the liver phase of malaria parasites are needed for more effective prevention of malaria in travelers.

[Malaria prevention in international travel]

For travelers malaria represents the principal infectious risk of severe complications and death. Infection during traveling depends on the geographical area visited, the predominant species of parasite, the frequency of resistance to antimalarial agents, and whether preventive measures have been taken. Until a vaccine has been developed, prevention strategies consist of providing travelers with information, the use of barrier methods against vector bites, the correct use of chemoprophylaxis, and the possibility of self-diagnosis and treatment. The choice of chemoprophylaxis regimen should be individualized since no regimen guarantees 100% protection or is free of adverse effects or contraindications. The most effective drugs are doxycycline, atovaquone-proguanil and mefloquine while those producing severe adverse effects with the least frequency are atovaquone-proguanil and doxycycline.

Prophylaxis failure due to probable mefloquine resistant P falciparum from Tanzania

Failures of mefloquine prophylaxis in travellers returning from Africa have been reported repeatedly. Non-compliance to chemoprophylaxis is considered to be a major factor for failure. Only few reports on mefloquine prophylaxis failure in sub-Saharan Africa were able to report blood levels of the drug that were sufficient for prophylactic effectiveness. We report the case of a 44-year-old German female who travelled to Tanzania for 3 weeks. The patient reported that she never missed a dose of mefloquine during her weekly prophylaxis schedule. Four weeks after returning from Tanzania, the patient presented with fever, headache and myalgia. Only a few trophozoites of Plasmodium falciparum were found in a thick film. Blood levels of mefloquine at that stage were at 1400 ng/ml, thus largely excluding non-compliance and malabsorption. To our knowledge, this is the first case of confirmed prophylaxis failure due to mefloquine resistance in East Africa.

Tolerability of doxycycline monohydrate salt vs. chloroquine-proguanil in malaria chemoprophylaxis

The resistance of Plasmodium falciparum to the chloroquine-proguanil association (C/P) as antimalarial chemoprophylaxis is becoming increasingly common in Africa. Daily oral doxycycline hyclate 100 mg is effective as malaria prophylaxis. But the hyclate salt's adverse effects combined with the capsule's galenic form are incompatible with good chemoprophylaxis compliance. We conducted a randomized group study of 522 French soldiers deployed in Gabon and Chad for 4 months to determine the tolerability of short-term malaria chemoprophylaxis with a 100-mg daily tablet of a monohydrate doxycycline salt compared with a daily C/P capsule. At days 7 and 120, compliance was better in the doxycycline group [respectively 98.5%vs. 73.9% (P < 0.001) and 90.5%vs. 74% (P < 0.001)]. No major event (evacuation, hospitalization) was related to the medications. Epigastralgia, diarrhoea, urticaria, mouth ulcers, sun sensitization and desquamation were significantly more frequent in the C/P group (P < 0.05). There was no statistical difference for malaria incidence, vertigo, nausea and hair loss. These results suggest that doxycycline monohydrate may be safely used in short-term malaria chemoprophylaxis. With the same efficacy as a hyclate doxycycline, doxycycline monohydrate could be a good chemoprophylaxis for short-term travellers at particular risk of C/P resistant P. falciparum malaria.

Endemic infectious diseases of Afghanistan

The current crisis in Afghanistan has resulted in an influx of Western military personnel, peacekeepers, humanitarian workers, and journalists. At the same time, unprecedented numbers of internally displaced persons and refugees have overwhelmed much of the already fragile infrastructure, setting the stage for outbreaks of infectious diseases among both foreigners and local populations. This review surveys the literature concerning the infectious diseases of Afghanistan and south-central Asia, with particular emphasis on diseases not typically seen in the Western world.

Safety evaluation of the drugs available to prevent malaria

All drugs used for malaria prophylaxis have common adverse effects, in addition to rare and/or severe adverse effects. For many of the drugs in current use, the common adverse effects include neuropsychiatric harms. This property makes these drugs unpopular with tourists and business travellers, most of whom will be well at the start of chemoprophylaxis. Drugs available to prevent malaria have not been rigorously researched in terms of the phenomenology of their unwanted effects. Consequently, prescribers are not well placed to give useful information to travellers on the incidence, natural history and avoidability of the harms they may experience from malaria chemoprophylaxis. There is some evidence that the adverse effects of mefloquine may be a post-hepatic syndrome caused by drug-induced liver damage with, in some users, symptomatic thyroid disturbance. However, confusion in the interpretation of the scientific evidence has led to conflicting messages regarding the safety of mefloquine and other antimalaria drugs, and to incorrect self-therapy by individual travellers, sometimes with fatal outcomes. In this review, the existing knowledge base for the safety of drugs currently used to prevent malaria is described along with present designs for future studies that would allow a rigorous safety assessment of candidate chemoprophylactic agents and of new drugs introduced to prevent malaria. There is an urgent need for internationally-agreed, evidence-based malaria prevention guidelines. These guidelines should be explicitly linked to the best available research evidence (normally systematic reviews of trials and individual randomised trials) and should highlight gaps in the knowledge base as priority areas for research.

Malaria chemoprophylaxis in the age of drug resistance. II. Drugs that may be available in the future

All current regimens of malaria chemoprophylaxis have serious drawbacks as a result of either suboptimal efficacy, difficulty with medication compliance, or adverse events. Two 8-aminoquinolines may be approaching registration, with primaquine having completed its prophylactic field testing and tafenoquine having begun advanced field testing at the end of 2000. Primaquine has long been used for management of relapses of malaria, but in the past decade, it has been reexamined for use in malaria prevention in order to stop infection in the liver. In field trials performed in Indonesia and Colombia, the efficacy of primaquine for malaria prevention was approximately 90%, compared with that of placebo. Because of its short half-life, primaquine requires daily administration. For adults, the prevention regimen is 30 mg base daily (0.5 mg base/kg/day), and it can probably be discontinued soon after departure from an area where malaria is endemic. To kill parasites that already exist in the liver, terminal prophylaxis is given after exposure to relapses of malaria infection; for adults, such prophylaxis usually consists of 15 mg base (0.3 mg base/kg/day) given daily for 2 weeks. Primaquine-induced gastrointestinal disturbances can be minimized if the drug is taken with food. Neither primaquine nor tafenoquine should be given to persons with glucose-6-phosphate dehydrogenase deficiency, to avoid the development of potentially severe drug-induced hemolysis. Tafenoquine is an analogue of primaquine that is more potent than the parent drug. Field trials in Kenya, Ghana, Gabon, and Southeast Asia have demonstrated an efficacy rate of approximately 90% for tafenoquine. Its long half-life allows for infrequent dosing (currently tested at 200 mg base/week), and its effect on parasites at the liver stage may allow for drug discontinuation at the time of departure from the area of endemicity.

Severe falciparum malaria in five soldiers from East Timor: a case series and literature review

Despite chemoprophylaxis, malaria remains a serious threat for large numbers of non-immune soldiers deployed in endemic areas. Five adult cases of severe falciparum malaria are reported. Three cases were complicated by multiorgan failure and one of these patients died from cerebral malaria. These cases serve to highlight issues, in an Australian intensive care unit, associated with the management of severe malaria, an uncommon disease in our country. The need for rapid diagnosis and commencement of appropriate treatment is paramount in preventing further morbidity and mortality. Understanding and management of malaria continues to evolve rapidly. The pathophysiology of acute lung injury, shock and brain injury associated with malaria are examined in light of recent research. This article discusses the current controversies of exchange blood transfusion and the use of the new artemisinin derivatives.

Use of malaria prevention measures by North American and European travelers to East Africa

BACKGROUND

The use of preventive measures, including effective chemoprophylaxis, is essential for protection against malaria among travelers. However, data have shown that travelers and medical advisors are confused by the lack of uniform recommendations and numerous prophylactic regimens of varying effectiveness that are used.

METHODS

To assess the use and type of preventive measures against malaria, we conducted a cross-sectional study in 1997 among travelers departing from the Nairobi and Mombasa airports in Kenya with European destinations.

RESULTS

Seventy-five percent of the travelers studied were residents of Europe and 25% were residents of North America; all stayed less than 1 year, and visited malarious areas. Most travelers, 97.1%, were aware of the risk and 91.3% sought pretravel medical advice. Although 95.4% used chemoprophylaxis and/or antimosquito measures, only 61.7% used both regular chemoprophylaxis and two or more antimosquito measures. Compliance with chemoprophylaxis was lowest amongst those who used a drug with a daily, as opposed to, a weekly dosing schedule, stayed more than 1 month, attributed an adverse health event to the chemoprophylaxis, and were less than 40 years of age. Among US travelers, 94.6% of those taking chemoprophylaxis were taking an effective regimen, that is, mefloquine or doxycycline. Only 1.9% used a suboptimal drug regimen, such as chloroquine/proguanil. Among European travelers, 69% used mefloquine or doxycycline, and 25% used chloroquine/proguanil. Notably, 45.3% of travelers from the UK used chloroquine/proguanil. Adverse events were noted by 19.7% of mefloquine users and 16.4% of travelers taking chloroquine/proguanil. Neuropsychologic adverse events were reported by 7.8% of users of mefloquine and 1.9% of those taking chloroquine/proguanil. The adverse events, however, had a lesser impact on compliance than frequent dosing schedule.

CONCLUSIONS

Health information should be targeted to travelers who are likely to use suboptimal chemoprophylaxis or may be noncompliant with prophylaxis. Uniform recommendations for effective chemoprophylaxis with simple dosing schedules are necessary to reduce rates of malaria among travelers to Africa.

Antimalarial chemoprophylaxis in infants and children

The evolving patterns of drug resistance in malaria parasites and changes in recommendations for malaria prevention present a challenge to physicians who advise travellers on chemoprophylaxis. Because compliance with personal protection measures is usually low, children should receive appropriate chemoprophylaxis, including breast-fed infants who are not protected through maternal chemoprophylaxis. For travel to areas where chloroquine resistance has not yet been reported (i.e. parts of Central America, the Caribbean and parts of the Middle East), chloroquine alone is sufficient for antimalarial prophylaxis. Mefloquine is the drug of choice for chemoprophylaxis in areas with chloroquine-resistant Plasmodium falciparum, and can be given to infants and young children. The combination of chloroquine and proguanil is well tolerated in children but is much less effective against drug-resistant malaria. Further research is needed to determine the best dosage regimen for antimalarial drugs used for chemoprophylaxis in children.