Causes of fever in returning travelers: a European multicenter prospective cohort study

Not all severe malaria cases are severe: Is it time to redefine severity criteria for malaria in non-endemic regions?

BACKGROUND

The current definition of severe malaria in non-endemic areas follows WHO criteria, which mainly target children in malaria-endemic areas, potentially misclassifying cases in non-endemic regions. We assessed the performance of a modified severe malaria classification criteria within our patient cohort.

METHODS

A cohort study of patients managed for malaria in a non-endemic setting (2005-2023) was analyzed. We classified patients into severe malaria (SM) using WHO 2013 criteria except for hyperparasitemia, where 2 % threshold was applied. Patients with SM were distinguished as very severe malaria (VSM) when presenting at least one of the following conditions: parasitemia >10 %, pulmonary edema, impaired consciousness, seizures, renal failure, metabolic acidosis or hyperlactatemia, shock or hypoglycemia. In patients with SM and no criteria for VSM, less severe malaria (LSM) was defined by: 2-10 % parasitemia, hyperbilirubinemia, prostration, anemia or minor bleeding. The primary composite outcome was death or the need for a life-saving intervention, as analyzed in the three comparative groups. Secondary outcome was the prevalence of co-infections.

RESULTS

Among 506 patients with malaria, 176 (34.8 %) presented with SM. A total of 37 (7.3 %) patients developed a life-threatening condition, namely death (n = 4) and/or the need for life-saving interventions (n = 34). All fatalities and 33 out of the 34 life-saving interventions occurred in the VSM group. Patients in LSM group did not develop any life-threatening conditions. As to co-infections, 28 (5.5 %) patients had a community-acquired co-infection, with no differences between groups (p = 0.763).

CONCLUSIONS

Severity criteria definitions would benefit from a review when assessing patients with malaria in non-endemic areas. Within the spectrum of SM, patients reclassified as LSM have a low risk of developing a life-threatening condition and present low co-infection incidence and could benefit from management out of intensive care units and a restrictive use of empirical antibiotics.

An observer-blind, randomised, placebo-controlled, phase 1, single ascending dose study of dengue monoclonal antibody in healthy adults in Australia

BACKGROUND

Dengue is highly prevalent in Asia and Latin America and has no specific dengue antiviral treatment. A recombinant monoclonal antibody (VIS513) that neutralises all four serotypes of the dengue virus has been developed in India. After confirmation of safety and efficacy in preclinical studies, it was tested in a first-in-human study to assess the safety and pharmacokinetics.

METHODS

This was a partially blind (observer-blind), randomised, placebo-controlled, phase 1, single ascending dose study in Australia. Participants were dengue naive, healthy adults (aged 18-45 years) with no clinically significant disorders or immunosuppressive conditions. Four dose levels of dengue monoclonal antibody (ie, 1 mg/kg, 3 mg/kg, 7 mg/kg, and 12 mg/kg; n=4 for 1 mg/kg and n=10 each for 3 mg/kg, 7 mg/kg, and 12 mg/kg doses) were assessed in a dose-ascending way with a placebo control (n=2 for each dose cohort, total n=6) for each cohort except for 1 mg/kg. Within each cohort, participants were first randomly assigned (1:1) in a sentinel sub-cohort and then randomly assigned (9:1) in an expansion sub-cohort to dengue monoclonal antibody or placebo except for the 1 mg/kg cohort. Participants, investigators, and outcome assessors were masked and treatment administrators were not masked. 40 participants received a single intravenous injection or infusion of either dengue monoclonal antibody or placebo over a period of 3 min to 2 h and were followed up until day 85. The primary outcomes were proportion of participants with adverse events and serious adverse events (SAEs) up to 84 days after dosing whereas the secondary outcomes were to assess the pharmacokinetic profile of dengue monoclonal antibody and to assess the presence of anti-drug antibody (ADA) to dengue monoclonal antibody. All participants were included in the safety analysis and the pharmacokinetic population involved participants receiving dengue monoclonal antibody. This study is registered with ClinicalTrials.gov, NCT03883620.

FINDINGS

Between March 22 and Dec 23, 2019, 40 healthy adults were randomly assigned and all completed the study. There were no SAEs reported. None of the placebo recipients (n=6) reported any adverse events. 31 (91%) of 34 participants receiving dengue monoclonal antibody reported 143 adverse events (1 mg/kg: four [100%] of four participants; 3 mg/kg: ten [100%] of ten participants; 7 mg/kg: seven [70%] of ten participants; 12 mg/kg: ten [100%] of ten participants). Of these 143 adverse events, 80 were treatment-related adverse events in 28 (82%) of 34 participants. Headache (16 [47%] of 34), infusion reaction (11 [32%] of 34), lymphopenia (seven [21%] of 34), fatigue (five [15%] of 34), and pyrexia (four [12%] of 34) were the most common reactions. Infusion reactions were reduced in the 7 mg/kg (two [20%] of ten participants) and 12 mg/kg (three [30%] of ten) cohorts with paracetamol premedication compared with the 3 mg/kg cohort (five [50%] of ten). The majority of adverse events were grade 1 or grade 2 in severity, and resolved completely. Median maximum serum concentrations ranged from 28 μg/mL (1 mg/kg) to 525 μg/mL (12 mg/kg). The median elimination half-life ranged from 775 h (1 mg/kg) to 878 h (12 mg/kg). No ADA against dengue monoclonal antibody was detected.

INTERPRETATION

Dengue monoclonal antibody was safe and well tolerated. It showed a dose-proportionate increase in pharmacokinetic exposure. These data support further evaluation of dengue monoclonal antibody in patients with dengue for safety and efficacy.

FUNDING

Serum Institute of India.

Infections diagnosed in children and young people screened for malaria in UK emergency departments: a retrospective multi-centre study

BACKGROUND

Data on imported infections in children and young people (CYP) are sparse.

AIMS

To describe imported infections in CYP arriving from malaria-endemic areas and presenting to UK emergency departments (ED) who were screened for malaria.

METHODS

This is a retrospective, multi-centre, observational study nested in a diagnostic accuracy study for malaria rapid diagnostic tests. Any CYP < 16 years presenting to a participating ED with a history of fever and travel to a malaria-endemic area between 1 January 2016 and 31 December 2017 and who had a malaria screen as a part of standard care were included. Geographical risk was calculated for the most common tropical infections.

RESULTS

Of the 1414 CYP screened for malaria, 44.0% (n = 622) arrived from South Asia and 33.3% (n = 471) from sub-Saharan Africa. Half (50.0%) had infections common in both tropical and non-tropical settings such as viral upper respiratory tract infection (URTI); 21.0% of infections were coded as tropical if gastro-enteritis is included, with a total of 4.2% (60) cases of malaria. CYP diagnosed with malaria were 7.44 times more likely to have arrived from sub-Saharan Africa than from South Asia (OR 7.44, 3.78-16.41).

CONCLUSION

A fifth of CYP presenting to participating UK EDs with fever and a history of travel to a malaria-endemic area and who were screened for malaria had a tropical infection if diarrhoea is included. A third of CYP had no diagnosis. CYP arriving from sub-Saharan Africa had the greatest risk of malaria.Abbreviations: CYP: children and young people; ED: emergency department; PERUKI: Paediatric Emergency Research in the UK and Ireland; RDT: rapid diagnostic test; VFR: visiting friends and relatives.

Imported infectious diseases in migrants from Latin America: A retrospective study from a referral centre for tropical diseases in Spain, 2017-2022

INTRODUCTION

Detecting imported diseases by migrants and individuals visiting friends and relatives (VFR) is key in the prevention and management of emergent infectious diseases acquired abroad.

METHODS

Retrospective descriptive study on migrants and VFR from Central and South America between 2017 and 2022 attended at a National Referral Centre for Tropical Diseases in Madrid, Spain. Demographic characteristics, syndromes and confirmed travel-related diagnoses were obtained from hospital patient medical records.

RESULTS

1654 cases were registered, median age of 42 years, 69.1% were female, and 55.2% were migrants. Most cases came from Bolivia (49.6%), followed by Ecuador (12.9%). Health screening while asymptomatic (31.6%) was the main reason for consultation, followed by Chagas disease follow-up (31%). Of those asymptomatic at screening, 47,2% were finally diagnosed of any disease, mainly Chagas disease (19,7%) and strongyloidiasis (10,2%) CONCLUSION: Our study emphasizes the importance of proactive health screening to detect asymptomatic conditions in migrants and VFR, enabling timely intervention and improved health outcomes. By understanding the unique health profiles of immigrant populations, targeted public health interventions can be devised to safeguard the well-being of these vulnerable groups.

Assessing viral metagenomics for the diagnosis of acute undifferentiated fever in returned travellers: a multicenter cohort study

BACKGROUND

Up to 45% of febrile returning travellers remain undiagnosed after a thorough diagnostic work-up, even at referral centres. Although metagenomic next-generation sequencing (mNGS) has emerged as a promising tool, evidence of its usefulness in imported fever is very limited.

METHODS

Travellers returning with fever were prospectively recruited in three referral clinics from November 2017 to November 2019. Unbiased mNGS optimised for virus detection was performed on serum samples of participants with acute undifferentiated febrile illness (AUFI), and results were compared to those obtained by reference diagnostic methods (RDM).

RESULTS

Among 507 returned febrile travellers, 433(85.4%) presented with AUFI. Dengue virus (n = 86) and Plasmodium spp. (n = 83) were the most common causes of fever. 103/433(23.8%) AUFI remained undiagnosed at the end of the follow-up.Metagenomic next-generation sequencing unveiled potentially pathogenic microorganisms in 196/433(38.7%) AUFI. mNGS identifications were more common in patients with a shorter duration of fever (42.3% in ≤5 days vs 28.7% in >5 days, P = 0.005). Potential causes of fever were revealed in 25/103(24.2%) undiagnosed AUFI and 5/23(21.7%) travellers with severe undiagnosed AUFI. Missed severe aetiologies included eight bacterial identifications and one co-infection of B19 parvovirus and Aspergillus spp.Additional identifications indicating possible co-infections occurred in 29/316(9.2%) travellers with AUFI, and in 11/128(8.6%) travellers with severe AUFI, who had received a diagnosis through RDM. The most common co-infections detected in severe AUFI were caused by Gram-negative bacteria. Serum mNGS was unable to detect >50% of infectious diagnoses achieved by RDM and also yielded 607 non-pathogenic identifications.

DISCUSSION

mNGS of serum can be a valuable diagnostic tool for selected travellers with undiagnosed AUFI or severe disease in addition to reference diagnostic techniques, especially during the first days of symptoms. Nevertheless, mNGS results interpretation presents a great challenge. Further studies evaluating the performance of mNGS using different sample types and protocols tailored to non-viral agents are needed.

Failure of artemether-lumefantrine therapy in travellers returning to Belgium with Plasmodium falciparum malaria: an observational case series with genomic analysis

BACKGROUND

Failure of artemisinin-based combination therapy is increasingly reported in patients with Plasmodium falciparum malaria in sub-Saharan Africa. We aimed to describe the clinical and genomic characteristics of recent cases of P. falciparum malaria failing artemether-lumefantrine in Belgium.

METHODS

Travel-related cases of malaria confirmed at the national reference laboratory of the Institute of Tropical Medicine, Antwerp, Belgium, were reviewed. All cases for which attending clinicians reported persistence (beyond Day 3 post-treatment initiation, i.e. early failure) or recrudescence (from Day 7 to 42, i.e. late failure) of P. falciparum parasites despite adequate drug intake were analysed. Both initial and persistent/recurrent samples were submitted to next generation sequencing to investigate resistance-conferring mutations.

RESULTS

From July 2022 to June 2023, eight P. falciparum cases of failure with artemether-lumefantrine therapy were reported (early failure = 1; late failure = 7). All travellers were returning from sub-Saharan Africa, most (6/8) after a trip to visit friends and relatives. PfKelch13 (PF3D7_1343700) mutations associated with resistance to artemisinin were found in two travellers returning from East Africa, including the validated marker R561H in the patient with early failure and the candidate marker A675V in a patient with late failure. Additional mutations were detected that could contribute to decreased susceptibility to artemisinin in another three cases, lumefantrine in six cases and proguanil in all eight participants. Various regimens were used to treat the persistent/recrudescent cases, with favourable outcome.

CONCLUSION

Within a 12-month period, we investigated eight travellers returning from sub-Saharan Africa with P. falciparum malaria and in whom artemether-lumefantrine failure was documented. Mutations conferring resistance to antimalarials were found in all analysed blood samples, especially against lumefantrine and proguanil, but also artemisinin. There is a pressing need for systematic genomic surveillance of resistance to antimalarials in international travellers with P. falciparum malaria, especially those experiencing treatment failure.

Usefulness of serial testing for the diagnosis of malaria in cases of fever upon return from travel

BACKGROUND

When malaria is suspected in case of fever after travel in endemic areas, the current recommendation is to repeat the malaria test at 24-hour intervals, with up to two additional tests, as long as the test result is negative. A retrospective analysis was conducted to investigate the appropriateness of this recommendation by determining the proportion of tests with negative result at first and subsequently with a positive one at second or third attempt.

METHODS

A retrospective study was conducted at the Centre for Primary Care and Public Health, Lausanne, covering a period of 15 years. All patients tested once for malaria were included. Testing included microscopy thick and thin films as well as malaria rapid diagnostic test used in combination. The main outcome measure was the proportion of patients with a first negative test result, subsequently positive on second or third test over the total patients with suspected malaria assessed. Demographic, travel, clinical, and laboratory variables were collected from patients' records to identify potential predictors of an initially negative and then positive test result.

RESULTS

Four thousand nine hundred seventy-two patients were included. Of those, 4557 (91.7%) had definitive negative test results, and 415 (8.3%) had a positive result on the first test [332/415 (80%) Plasmodium falciparum, 40/415 (9.6%) P. vivax, 21/415 (5.1%) P. ovale, 12/415 (2.9%) P. vivax/ovale, 9/415 (2.2%) P. malariae and 1/415 (0.2%) P. knowlesi], and 3/4972 (0.06%) had a positive result on the second test after a first negative result, 1/4972(0.02%) had a positive test result after 2 negative results, all with P. falciparum. One of the four patients that were positive after their initial negative test was pregnant. The very small number of patients with an initially negative test result and secondarily positive did not allow for risk factor analysis.

CONCLUSIONS

The current recommendation of serial malaria testing is not supported by the present study, a fortiori for those who do not present with a strong clinical or laboratory predictor of malaria.

MALrisk: a machine-learning–based tool to predict imported malaria in returned travellers with fever

BACKGROUND

Early diagnosis is key to reducing the morbi-mortality associated with P. falciparum malaria among international travellers. However, access to microbiological tests can be challenging for some healthcare settings. Artificial Intelligence could improve the management of febrile travellers.

METHODS

Data from a multicentric prospective study of febrile travellers was obtained to build a machine-learning model to predict malaria cases among travellers presenting with fever. Demographic characteristics, clinical and laboratory variables were leveraged as features. Eleven machine-learning classification models were evaluated by 50-fold cross-validation in a Training set. Then, the model with the best performance, defined by the Area Under the Curve (AUC), was chosen for parameter optimization and evaluation in the Test set. Finally, a reduced model was elaborated with those features that contributed most to the model.

RESULTS

Out of eleven machine-learning models, XGBoost presented the best performance (mean AUC of 0.98 and a mean F1 score of 0.78). A reduced model (MALrisk) was developed using only six features: Africa as a travel destination, platelet count, rash, respiratory symptoms, hyperbilirubinemia and chemoprophylaxis intake. MALrisk predicted malaria cases with 100% (95%CI 96-100) sensitivity and 72% (95%CI 68-75) specificity.

CONCLUSIONS

The MALrisk can aid in the timely identification of malaria in non-endemic settings, allowing the initiation of empiric antimalarials and reinforcing the need for urgent transfer in healthcare facilities with no access to malaria diagnostic tests. This resource could be easily scalable to a digital application and could reduce the morbidity associated with late diagnosis.

Coinfections and antimicrobial treatment in a cohort of falciparum malaria in a non-endemic country: a 10-year experience

INTRODUCTION

Falciparum malaria remains one of the deadliest infectious diseases worldwide. In Germany, it is mainly an imported infection among travellers. Rates of coinfection are often unknown, and a clinical rationale for the beneficial use of calculated antibiotic therapy in patients with malaria and suspected coinfection is lacking.

METHODS

We conducted an analysis of all in-patients treated with falciparum malaria at a German infectious diseases centre in vicinity to one of Europe's major airports for 2010-2019. Logistic regression and time-to-event analysis were used to evaluate predictors for bacterial coinfection, the use of antibacterial substances, as well as their influence on clinical course.

RESULTS

In total, 264 patients were included. Of those, 64% received an additional antibacterial therapy (n = 169). Twenty-nine patients (11.0%) were found to have suffered from a relevant bacterial coinfection, while only a small fraction had relevant bacteremia (n = 3, 1.4%). However, patients with severe malaria did not suffer from coinfections more frequently (p = 0.283). CRP levels were not a reliable predictor for a bacterial coinfection (OR 0.99, 95% CI 0.94-1.06, p = 0.850), while another clinical focus of infection was positively associated (OR 3.86, 95% CI 1.45-11.55, p  = 0.010).

CONCLUSION

Although bacterial coinfections were rare in patients with malaria at our centre, the risk does not seem negligible. These data point rather towards individual risk assessment in respective patients than to general empiric antibiotic use.

Chikungunya infection in returned travellers: results from the geosentinel network, 2005-2020

BACKGROUND

Chikungunya is an important travel-related disease because of its rapid geographical expansion and potential for prolonged morbidity. Improved understanding of the epidemiology of travel-related chikungunya infections may influence prevention strategies including education and vaccination.

METHODS

We analysed data from travellers with confirmed or probable chikungunya reported to GeoSentinel sites from 2005 to 2020. Confirmed chikungunya was defined as a compatible clinical history plus either virus isolation, positive nucleic acid test or seroconversion/rising titre in paired sera. Probable chikungunya was defined as a compatible clinical history with a single positive serology result.

RESULTS

1202 travellers (896 confirmed and 306 probable) with chikungunya were included. The median age was 43 years (range 0-91; interquartile range [IQR]: 31-55); 707 (58.8%) travellers were female. Most infections were acquired in the Caribbean (28.8%), Southeast Asia (22.8%), South Central Asia (14.2%) and South America (14.2%). The highest numbers of chikungunya cases reported to GeoSentinel were in 2014 (28.3%), 2015 (14.3%) and 2019 (11.9%). The most frequent reasons for travel were tourism (n = 592; 49.3%) and visiting friends or relatives (n = 334; 27.7%). The median time to presentation to a GeoSentinel site was 23 days (IQR: 7-52) after symptom onset. In travellers with confirmed chikungunya and no other reported illnesses, the most frequently reported symptoms included musculoskeletal symptoms (98.8%), fever/chills/sweats (68.7%) and dermatologic symptoms (35.5%). Among 917 travellers with information available, 296 (32.3%) had a pretravel consultation.

CONCLUSIONS

Chikungunya was acquired by international travellers in almost 100 destinations globally. Vector precautions and vaccination where recommended should be integrated into pretravel visits for travellers going to areas with chikungunya or areas with the potential for transmission. Continued surveillance of travel-related chikungunya may help public health officials and clinicians limit the transmission of this potentially debilitating disease by defining regions where protective measures (e.g. pretravel vaccination) should be strongly considered.

The epidemiology of imported and locally acquired dengue in Australia, 2012-2022

BACKGROUND

Dengue is the most important arboviral disease globally and poses ongoing challenges for control including in non-endemic countries with competent mosquito vectors at risk of local transmission through imported cases. We examined recent epidemiological trends in imported and locally acquired dengue in Australia, where the Wolbachia mosquito population replacement method was implemented throughout dengue-prone areas of northern Queensland between 2011 and 2019.

METHODS

We analysed dengue cases reported to the Australian National Notifiable Disease Surveillance System between January 2012 and December 2022, and Australian traveller movement data.

RESULTS

Between 2012 and 2022, 13 343 dengue cases were reported in Australia (median 1466 annual cases); 12 568 cases (94.2%) were imported, 584 (4.4%) were locally acquired and 191 (1.4%) had no origin recorded. Locally acquired cases decreased from a peak in 2013 (n = 236) to zero in 2021-22. Annual incidence of imported dengue ranged from 8.29/100 000 (n = 917 cases) to 22.10/100 000 (n = 2203) annual traveller movements between 2012 and 2019, decreased in 2020 (6.74/100 000 traveller movements; n = 191) and 2021 (3.32/100 000 traveller movements; n = 10) during COVID-19-related border closures, then rose to 34.79/100 000 traveller movements (n = 504) in 2022. Imported cases were primarily acquired in Southeast Asia (n = 9323; 74%), Southern and Central Asia (n = 1555; 12%) and Oceania (n = 1341; 11%). Indonesia (n = 5778; 46%) and Thailand (n = 1483; 12%) were top acquisition countries. DENV-2 (n = 2147; 42%) and DENV-1 (n = 1526; 30%) were predominant serotypes.

CONCLUSION

Our analysis highlights Australia's successful control of locally acquired dengue with Wolbachia. Imported dengue trends reflect both Australian travel destinations and patterns and local epidemiology in endemic countries.

Proceedings of the 6th Asia Dengue Summit, June 2023

The 6th Asia Dengue Summit (ADS) themed "Road Map to Zero Dengue Death" was held in Thailand from 15th-16th June 2023. The summit was hosted by Tropical Medicine Cluster, Chulalongkorn University, Bangkok, Thailand in conjunction with Queen Saovabha Memorial Institute, The Thai Red Cross Society; Faculty of Tropical Medicine, Mahidol University; and the Ministry of Public Health. The 6th ADS was convened by Asia Dengue Voice and Action (ADVA); Global Dengue and Aedes Transmitted Diseases Consortium (GDAC); Southeast Asian Ministers of Education Tropical Medicine and Public Health Network (SEAMEO TROPMED); Fondation Mérieux (FMx) and the International Society for Neglected Tropical Diseases (ISNTD). Dengue experts from academia and research, and representatives from the Ministries of Health, Regional and Global World Health Organization (WHO) and International Vaccine Institute (IVI) participated in the three-day summit. With more than 51 speakers and 451 delegates from over 24 countries, 10 symposiums, and 2 full days, the 6th ADS highlighted the growing threat of dengue and its antigenic evolution, flagged the urgent need to overcome vaccine hesitancy and misinformation crisis, and focused on dengue control policies, newer diagnostics, therapeutics and vaccines, travel-associated dengue, and strategies to improve community involvement.

Injuries and medical emergencies among international travellers

BACKGROUND

Tropical infectious diseases and vaccine-preventable emergencies are the mainstay of pre-travel consultations. However, non-communicable diseases, injuries and accidents that occur during travel are not emphasized enough in these settings.

METHODS

We performed a narrative review based on a literature search of PubMed, Google Scholar, UpToDate, DynaMed and LiSSa and on reference textbooks and medical journals dedicated to travel, emergency and wilderness medicine. Relevant secondary references were extracted. We also aimed to discuss newer or neglected issues, such as medical tourism, Coronavirus Disease 2019, exacerbations of co-morbidities associated with international travel, insurance coverage, health care seeking abroad, medical evacuation or repatriation and tips for different types of travellers' emergency medical kits (personal, group, physician handled).

RESULTS

All sources reviewed led to the selection of >170 references. Among epidemiological data on morbidity and deaths while abroad, only retrospective data are available. Deaths are estimated to occur in 1 in 100 000 travellers, with 40% caused by trauma and 60% by diseases, and <3% linked to infectious diseases. Trauma and other injuries acquired during travel, such as traffic accidents and drowning, can be reduced by up to 85% with simple preventive recommendations such as avoiding simultaneous alcohol intake. In-flight emergencies occur on 1 in 604 flights on average. Thrombosis risk is two to three times greater for travellers than for non-travellers. Fever during or after travel can occur in 2-4% of travellers, but in up to 25-30% in tertiary centres. Traveller's diarrhoea, although rarely severe, is the most common disease associated with travel. Autochthonous emergencies (acute appendicitis, ectopic pregnancy, dental abscess) can also occur.

CONCLUSIONS

Pre-travel medicine encounters must include the topic of injuries and medical emergencies, such as the risk-taking behaviours and foster better planning in a comprehensive approach along with vaccines and infectious diseases advices.

Rapid diagnostic tests for dengue would reduce hospitalizations, healthcare costs and antibiotic prescriptions in Spain: A cost-effectiveness analysis

BACKGROUND

Current gold standard diagnostic techniques for dengue are expensive and time-consuming. Rapid diagnostic tests (RDTs) have been proposed as alternatives, although data about their potential impact in non-endemic areas is scarce.

METHODS

We performed a cost-effectiveness analysis comparing the costs of dengue RDTs to the current standard of care for the management of febrile returning travelers in Spain. Effectiveness was measured in terms of potential averted hospital admissions and reduction of empirical antibiotics, based on 2015-2020 dengue admissions at Hospital Clinic Barcelona (Spain).

RESULTS

Dengue RDTs were associated with 53.6% (95% CI: 33.9-72.5) reduction of hospital admissions and were estimated to save 289.08-389.31€ per traveler tested. Moreover, RDTs would have avoided the use of antibiotics in 46.4% (95% CI: 27.5-66.1) of dengue patients.

DISCUSSION

Implementation of dengue RDTs for the management of febrile travelers is a cost-saving strategy that would lead to a reduction of half of dengue admissions and a reduction of inappropriate antibiotics in Spain.

A new dengue vaccine (TAK-003) now WHO recommended in endemic areas; what about travellers?

Qdenga (Takeda) is now WHO recommended for residents of highly endemic areas. Travellers from dengue non-endemic countries with previous travel-related dengue (any serotype) will benefit from TAK-003 vaccination to prevent a secondary dengue infection during future dengue risk travel. Dengue-naïve travellers have less potential benefit and use will remain discretionary for now.

Asymptomatic arbovirus and campylobacter infections in German travelers to Asia

The true risk for many travel diseases is unknown because most studies do not detect asymptomatic infections. In this study, we performed ELISA for dengue virus (DENV), chikungunya virus (CHIKV), Zika virus (ZIKV), hepatitis E virus (HEV), and Campylobacter jejuni on samples from 81 healthy Germans before and after they traveled to Asia. ELISA found five seroconversions for C. jejuni, two for DENV, one for ZIKV, and zero for HEV. For CHIKV, three subjects were positive before travel and negative afterwards. None had symptoms. These infections would have gone unnoticed by retrospective studies. Therefore, the risk for these infections may be higher than previously estimated.

Travel-related respiratory symptoms and infections in travellers (2000-22): a systematic review and meta-analysis

BACKGROUND

Respiratory tract infections (RTIs) are common in travellers due to the year-round or seasonal presence of respiratory pathogen and exposure to crowded environments during the itinerary. No study has systematically examined the burden of RTI infections among travellers. The aim of this systematic review and meta-analysis is to evaluate the prevalence of RTIs and symptoms suggestive of RTIs among travellers according to risk groups and/or geographic region, and to describe the spectrum of RTIs.

METHODS

The systematic review and meta-analysis was registered in PROSPERO (CRD42022311261). We searched Medline, Embase, Scopus, Cochrane Central, Web of Science, Science Direct and preprint servers MedRxiv, BioRxiv, SSRN and IEEE Xplore on 1 February 2022. Studies reporting RTIs or symptoms suggestive of RTIs in international travellers after 1 January 2000 were eligible. Data appraisal and extraction were performed by two authors, and proportional meta-analyses were used to obtain estimates of the prevalence of respiratory symptoms and RTIs in travellers and predefined risk groups.

FINDINGS

A total of 429 articles on travellers' illness were included. Included studies reported 86 841 symptoms suggestive of RTIs and 807 632 confirmed RTIs. Seventy-eight percent of reported respiratory symptoms and 60% of RTIs with available location data were acquired at mass gatherings events. Cough was the most common symptom suggestive of respiratory infections, and the upper respiratory tract was the most common site for RTIs in travellers. The prevalence of RTIs and respiratory symptoms suggestive of RTIs were 10% [8%; 14%] and 37% [27%; 48%], respectively, among travellers. Reporting of RTIs in travellers denoted by publication output was found to correlate with global waves of new respiratory infections.

INTERPRETATION

This study demonstrates a high burden of RTIs among travellers and indicates that travellers' RTIs reflect respiratory infection outbreaks. These findings have important implications for understanding and managing RTIs among travellers.

Clinical Characteristics and Outcomes Among Travelers With Severe Dengue : A GeoSentinel Analysis

BACKGROUND

Dengue virus is a flavivirus transmitted by Aedes mosquitoes and is an important cause of illness worldwide. Data on the severity of travel-associated dengue illness are limited.

OBJECTIVE

To describe the epidemiology, clinical characteristics, and outcomes among international travelers with severe dengue or dengue with warning signs as defined by the 2009 World Health Organization classification (that is, complicated dengue).

DESIGN

Retrospective chart review and analysis of travelers with complicated dengue reported to GeoSentinel from January 2007 through July 2022.

SETTING

20 of 71 international GeoSentinel sites.

PATIENTS

Returning travelers with complicated dengue.

MEASUREMENTS

Routinely collected surveillance data plus chart review with abstraction of clinical information using predefined grading criteria to characterize the manifestations of complicated dengue.

RESULTS

Of 5958 patients with dengue, 95 (2%) had complicated dengue. Eighty-six (91%) patients had a supplemental questionnaire completed. Eighty-five of 86 (99%) patients had warning signs, and 27 (31%) were classified as severe. Median age was 34 years (range, 8 to 91 years); 48 (56%) were female. Patients acquired dengue most frequently in the Caribbean (n = 27 [31%]) and Southeast Asia (n = 21 [24%]). Frequent reasons for travel were tourism (46%) and visiting friends and relatives (32%). Twenty-one of 84 (25%) patients had comorbidities. Seventy-eight (91%) patients were hospitalized. One patient died of nondengue-related illnesses. Common laboratory findings and signs were thrombocytopenia (78%), elevated aminotransferase (62%), bleeding (52%), and plasma leakage (20%). Among severe cases, ophthalmologic pathology (n = 3), severe liver disease (n = 3), myocarditis (n = 2), and neurologic symptoms (n = 2) were reported. Of 44 patients with serologic data, 32 confirmed cases were classified as primary dengue (IgM+/IgG-) and 12 as secondary (IgM-/IgG+) dengue.

LIMITATIONS

Data for some variables could not be retrieved by chart review for some patients. The generalizability of our observations may be limited.

CONCLUSION

Complicated dengue is relatively rare in travelers. Clinicians should monitor patients with dengue closely for warning signs that may indicate progression to severe disease. Risk factors for developing complications of dengue in travelers need further prospective study.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention, International Society of Travel Medicine, Public Health Agency of Canada, and GeoSentinel Foundation.

Travel-associated melioidosis: a narrative review

BACKGROUND

Melioidosis, caused by Burkholderia pseudomallei, may be considered a neglected tropical disease that remains underdiagnosed in many geographical areas. Travellers can act as the sentinels of disease activity, and data from imported cases may help complete the global map of melioidosis.

METHODS

A literature search for imported melioidosis for the period 2016-22 was performed in PubMed and Google Scholar.

RESULTS

In total, 137 reports of melioidosis associated with travel were identified. The majority were males (71%) and associated with exposure in Asia (77%) (mainly Thailand, 41%, and India, 9%). A minority acquired the infection in the Americas-Caribbean area (6%), Africa (5%) and Oceania (2%). The most frequent comorbidity was diabetes mellitus (25%) followed by underlying pulmonary, liver or renal disease (8, 5 and 3%, respectively). Alcohol/tobacco use were noted for seven and six patients, respectively (5%). Five patients (4%) had associated non-human immunodeficiency virus (HIV)-related immunosuppression, and three patients (2%) had HIV infection. One patient (0.8%) had concomitant coronavirus disease 19. A proportion (27%) had no underlying diseases. The most frequent clinical presentations included pneumonia (35%), sepsis (30%) and skin/soft tissue infections (14%). Most developed symptoms <1 week after return (55%), and 29% developed symptoms >12 weeks after. Ceftazidime and meropenem were the main treatments used during the intensive intravenous phase (52 and 41% of patients, respectively) and the majority (82%) received co-trimoxazole alone/combination, for the eradication phase. Most patients had a favourable outcome/survived (87%). The search also retrieved cases in imported animals or cases secondary to imported commercial products.

CONCLUSIONS

As post-pandemic travel soars, health professionals should be aware of the possibility of imported melioidosis with its diverse presentations. Currently, no licensed vaccine is available, so prevention in travellers should focus on protective measures (avoiding contact with soil/stagnant water in endemic areas). Biological samples from suspected cases require processing in biosafety level 3 facilities.

Healthcare seeking during travel: an analysis by the GeoSentinel surveillance network of travel medicine providers

BACKGROUND

International travellers may seek care abroad to address health problems that arise during their trip or plan healthcare outside their country of residence as medical tourists.

METHODS

Data were collected on travellers evaluated at GeoSentinel Network sites who reported healthcare during travel. Both unplanned and planned healthcare were analysed, including the reason and nature of healthcare sought, characteristics of the treatment provided and outcomes. Travellers that presented for rabies post-exposure prophylaxis were described elsewhere and were excluded from detailed analysis.

RESULTS

From May 2017 through June 2020, after excluding travellers obtaining rabies post-exposure prophylaxis (n= 415), 1093 travellers reported care for a medical or dental issue that was an unanticipated part of the travellers' planned itinerary (unplanned healthcare). Travellers who sought unplanned healthcare abroad had frequent diagnoses of acute diarrhoea, dengue, falciparum malaria and unspecified viral syndrome, and obtained care in 131 countries. Thirty-four (3%) reported subsequent deterioration and 230 (21%) reported no change in condition; a third (n = 405; 37%) had a pre-travel health encounter. Forty-one travellers had sufficient data on planned healthcare abroad for analysis. The most common destinations were the US, France, Dominican Republic, Belgium and Mexico. The top reasons for their planned healthcare abroad were unavailability of procedure at home (n = 9; 19%), expertise abroad (n = 9; 19%), lower cost (n = 8; 17%) and convenience (n = 7; 15%); a third (n = 13; 32%) reported cosmetic or surgical procedures. Early and late complications occurred in 14 (33%) and 4 (10%) travellers, respectively. Four travellers (10%) had a pre-travel health encounter.

CONCLUSIONS

International travellers encounter health problems during travel that often could be prevented by pre-travel consultation. Travellers obtaining planned healthcare abroad can experience negative health consequences associated with treatments abroad, for which pre-travel consultations could provide advice and potentially help to prevent complications.

Doxycycline responding illnesses in returning travellers with undifferentiated non-malaria fever: a European multicentre prospective cohort study

BACKGROUND

Diagnosis of undifferentiated non-malaria fevers (NMF) in returning travellers is a great challenge. Currently, there is no consensus about the use of empirical antibiotics in returning travellers with undifferentiated NMF. Although studies in endemic areas showed that a wide range of pathogens implicated in undifferentiated NMF are treatable with doxycycline, the role of doxycycline in returning travellers with fever still has to be explored.

METHODS

Prospective European multicentre cohort study of febrile international travellers (November 2017-November 2019). Immunological and molecular diagnostic techniques for doxycycline responding illnesses (DRI) agents such as Anaplasma phagocytophilum, spotted fever group Rickettsia spp., typhus group Rickettsia spp., Coxiella burnetii, Bartonella spp., Orientia tsutsugamushi, Borrelia miyamotoi, Borrelia recurrentis and Leptospira spp. were systematically performed in all patients with undifferentiated NMF. We estimated the prevalence and predictive factors of DRI in returning travellers with undifferentiated NMF.

RESULTS

Among 347 travellers with undifferentiated NMF, 106 (30·5%) were finally diagnosed with DRI. Only 57 (53·8%) of the 106 DRI infections were diagnosed by the standard of care. The main causes of DRI were: 55 (51·9%) Rickettsia spp., 16 (15·1%) C. burnetii; 15 (14·2%) Bartonella spp.; 13 (12·3%) Leptospira spp. and 10 (9·5%) A. phagocytophilum. The only predictive factor associated with DRI was presenting an eschar (aOR 39·52, 95%CI 4·85-322·18). Features of dengue such as retro-orbital pain (aOR 0·40, 95%CI 0·21-0·76) and neutropenia (aOR 0·41, 95%CI 0·21-0·79) were negatively associated with DRI.

CONCLUSIONS

Although DRI are responsible for 30% of undifferentiated NMF cases in travellers, those are seldom recognized during the first clinical encounter. Empirical treatment with doxycycline should be considered in returning travellers with undifferentiated fever and negative tests for malaria and dengue, particularly when presenting severe illness, predictive factors for rickettsiosis or no features of dengue.

Mycoplasma haemohominis as a cause of fever of unknown origin in a traveller

Candidatus mycoplasma haemohominis (cMh) is the most human-adapted and lethal haemoplasma. Bats are the common reservoir worldwide. cMh should be suspected in fever of unknown origin associated with splenomegaly, and haemolytic anaemia or haemophagocytic lymphohistiocytosis, above all in Asia Pacific travellers. Doxycycline should  be started preemptively as diagnosis can be retrospectively confirmed.

Melioidosis in a traveller from Africa

A high index of suspicion is necessary to diagnose imported melioidosis in travellers from Africa. Known risk factors include diabetes mellitus, old age and exposure to soil and water. Processing of samples may pose a risk and requires handling in a biosafety level 3 facility.

The Emergence of Travel-related Infections in Critical Care Units

Several tropical or geographically confined infectious diseases may lead to organ failure requiring management in an intensive care unit (ICU), both in endemic low- and middle-income countries where ICU facilities are increasingly being developed and in (nonendemic) high-income countries through an increase in international travel and migration. The ICU physician must know which of these diseases may be encountered and how to recognize, differentiate, and treat them. The four historically most prevalent "tropical" diseases (malaria, enteric fever, dengue, and rickettsiosis) can present with single or multiple organ failure in a very similar manner, which makes differentiation based solely on clinical signs very difficult. Specific but frequently subtle symptoms should be considered and related to the travel history of the patient, the geographic distribution of these diseases, and the incubation period. In the future, ICU physicians may also be more frequently confronted with rare but frequently lethal diseases, such as Ebola and other viral hemorrhagic fevers, leptospirosis, and yellow fever. No one could have foreseen the worldwide 2019-up to now coronavirus disease 2019 (COVID-19) crisis caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was initially spread by travel too. In addition, the actual pandemic due to SARS-CoV-2 reminds us of the actual and potential threat of (re)-emerging pathogens. If left untreated or when treated with a delay, many travel-related diseases remain an important cause of morbidity and even mortality, even when high-quality critical care is provided. Awareness and a high index of suspicion of these diseases is a key skill for the ICU physicians of today and tomorrow to develop.

A randomized, placebo-controlled, blinded phase 1 study investigating a novel inactivated, Vero cell-culture derived Zika virus vaccine

BACKGROUND

Zika virus (ZIKV) is an emerging public health threat, rendering development of a safe and effective vaccine against the virus a high priority to face this unmet medical need. Our vaccine candidate has been developed on the same platform used for the licensed vaccine IXIARO®, a vaccine against Japanese Encephalitis virus, another closely related member of the Flaviviridae family.

METHODS

Between February 24, 2018 and November 16, 2018, we conducted a randomized, observer-blinded, placebo controlled, single center phase 1 study to assess the safety and immunogenicity of an adjuvanted, inactivated, purified whole-virus Zika vaccine candidate in the U.S. A total of 67 healthy flavivirus-naïve adults aged 18 to 49 years were randomly assigned to one of five study arms to receive two immunizations of either high dose or low dose (6 antigen units or 3 antigen units) with both dose levels applied in two different immunization regimens or placebo as control.

RESULTS

Our vaccine candidate showed an excellent safety profile independent of dose and vaccination regimen with predominantly mild adverse events. No serious adverse event has been reported. The ZIKV vaccine induced neutralizing antibodies in all tested doses and regimens with seroconversion rates up to 85.7% (high dose), which remained up to 40% (high dose) at 6 months follow-up. Of note, the rapid regimen triggered a substantial immune response within days.

CONCLUSIONS

The rapid development and production of a ZIKV vaccine candidate building on a commercial Vero-cell manufacturing platform resulted in a safe and immunogenic vaccine suitable for further clinical development. To optimize antibody persistence, higher doses and a booster administration might be considered.

Malaria Surveillance — United States, 2018

Problem/Condition

Malaria in humans is caused by intraerythrocytic protozoa of the genus Plasmodium. These parasites are transmitted by the bite of an infective female Anopheles species mosquito. Most malaria infections in the United States and its territories occur among persons who have traveled to regions with ongoing malaria transmission. However, among persons who have not traveled out of the country, malaria is occasionally acquired through exposure to infected blood or tissues, congenital transmission, nosocomial exposure, or local mosquitoborne transmission. Malaria surveillance in the United States and its territories provides information on its occurrence (e.g., temporal, geographic, and demographic), guides prevention and treatment recommendations for travelers and patients, and facilitates rapid transmission control measures if locally acquired cases are identified.

Period Covered

This report summarizes confirmed malaria cases in persons with onset of illness in 2018 and trends in previous years.

Description of System

Malaria cases diagnosed by blood smear microscopy, polymerase chain reaction, or rapid diagnostic tests are reported to local and state health departments through electronic laboratory reports or by health care providers or laboratory staff members directly reporting to CDC or health departments. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), the National Notifiable Diseases Surveillance System (NNDSS), or direct CDC clinical consultations. CDC reference laboratories provide diagnostic assistance and conduct antimalarial drug resistance marker testing on blood specimens submitted by health care providers or local or state health departments. This report summarizes data from the integration of all cases from NMSS and NNDSS, CDC clinical consultations, and CDC reference laboratory reports.

Results

CDC received reports of 1,823 confirmed malaria cases with onset of symptoms in 2018, including one cryptic case and one case acquired through a bone marrow transplant. The number of cases reported in 2018 is 15.6% fewer than in 2017. The number of cases diagnosed in the United States and its territories has been increasing since the mid-1970s; the number of cases reported in 2017 was the highest since 1972. Of the cases in 2018, a total of 1,519 (85.0%) were imported cases that originated from Africa; 1,061 (69.9%) of the cases from Africa were from West Africa, a similar proportion to what was observed in 2017. Among all cases, P. falciparum accounted for most infections (1,273 [69.8%]), followed by P. vivax (173 [9.5%]), P. ovale (95 [5.2%]), and P. malariae (48 [2.6%]). For the first time since 2008, an imported case of P. knowlesi was identified in the United States and its territories. Infections by two or more species accounted for 17 cases (<1.0%). The infecting species was not reported or was undetermined in 216 cases (11.9%). Most patients (92.6%) had symptom onset <90 days after returning to the United States or its territories from a country with malaria transmission. Of the U.S. civilian patients who reported reason for travel, 77.0% were visiting friends and relatives. Chemoprophylaxis with antimalarial medications are recommended for U.S. residents to prevent malaria while traveling in countries where it is endemic. Fewer U.S. residents with imported malaria reported taking any malaria chemoprophylaxis in 2018 (24.5%) than in 2017 (28.4%), and adherence was poor among those who took chemoprophylaxis. Among the 864 U.S. residents with malaria for whom information on chemoprophylaxis use and travel region were known, 95.0% did not adhere to or did not take a CDC-recommended chemoprophylaxis regimen. Among 683 women with malaria, 19 reported being pregnant. Of these, 11 pregnant women were U.S. residents, and one of whom reported taking chemoprophylaxis to prevent malaria but her adherence to chemoprophylaxis was not reported. Thirty-eight (2.1%) malaria cases occurred among U.S. military personnel in 2018, more than in 2017 (26 [1.2%]). Among all reported malaria cases in 2018, a total of 251 (13.8%) were classified as severe malaria illness, and seven persons died from malaria. In 2018, CDC analyzed 106 P. falciparum-positive and four P. falciparum mixed species specimens for antimalarial resistance markers (although certain loci were untestable in some specimens); identification of genetic polymorphisms associated with resistance to pyrimethamine were found in 99 (98.0%), to sulfadoxine in 49 (49.6%), to chloroquine in 50 (45.5%), and to mefloquine in two (2.0%); no specimens tested contained a marker for atovaquone or artemisinin resistance.

Interpretation

The importation of malaria reflects the overall trends in global travel to and from areas where malaria is endemic, and 15.6% fewer cases were imported in 2018 compared with 2017. Of imported cases, 59.3% were among persons who had traveled from West Africa. Among U.S. civilians, visiting friends and relatives was the most common reason for travel (77.1%).

Public Health Actions

The best way for U.S. residents to prevent malaria is to take chemoprophylaxis medication before, during, and after travel to a country where malaria is endemic. Adherence to recommended malaria prevention strategies among U.S. travelers would reduce the number of imported cases. Reported reasons for nonadherence include prematurely stopping after leaving the area where malaria was endemic, forgetting to take the medication, and experiencing a side effect. Health care providers can make travelers aware of the risks posed by malaria and incorporate education to motivate them to be adherent to chemoprophylaxis. Malaria infections can be fatal if not diagnosed and treated promptly with antimalarial medications appropriate for the patient’s age, pregnancy status, medical history, the likely country of malaria acquisition, and previous use of antimalarial chemoprophylaxis. Antimalarial use for chemoprophylaxis and treatment should be determined by the CDC guidelines, which are frequently updated. In April 2019, intravenous (IV) artesunate became the first-line medication for treatment of severe malaria in the United States and its territories. Artesunate was approved by the Food and Drug Administration (FDA) in 2020 and is commercially available (Artesunate for Injection) from major U.S. drug distributors (https://amivas.com). Stocking IV artesunate locally allows for immediate treatment of severe malaria once diagnosed and provides patients with the best chance of a complete recovery and no sequelae. With commercial IV artesunate now available, CDC will discontinue distribution of non–FDA-approved IV artesunate under an investigational new drug protocol on September 30, 2022. Detailed recommendations for preventing malaria are online at https://www.cdc.gov/malaria/travelers/drugs.html. Malaria diagnosis and treatment recommendations are also available online at https://www.cdc.gov/malaria/diagnosis_treatment. Health care providers who have sought urgent infectious disease consultation and require additional assistance on diagnosis and treatment of malaria can call the Malaria Hotline 9:00 a.m.–5:00 p.m. Eastern Time, Monday–Friday, at 770-488-7788 or 855-856-4713 or after hours for urgent inquiries at 770-488-7100. Persons submitting malaria case reports (care providers, laboratories, and state and local public health officials) should provide complete information because incomplete reporting compromises case investigations and public health efforts to prevent future infections and examine trends in malaria cases. Molecular surveillance of antimalarial drug resistance markers enables CDC to track, guide treatment, and manage drug resistance in malaria parasites both domestically and globally. A greater proportion of specimens from domestic malaria cases are needed to improve the completeness of antimalarial drug resistance analysis; therefore, CDC requests that blood specimens be submitted for any case of malaria diagnosed in the United States and its territories.