Closing the gap in travel medicine: reframing research questions for a new era

UiO-66 nanoparticles combat influenza A virus in mice by activating the RIG-I-like receptor signaling pathway

The Influenza A virus (IAV) is a zoonotic pathogen that infects humans and various animal species. Infection with IAV can cause fever, anorexia, and dyspnea and is often accompanied by pneumonia characterized by an excessive release of cytokines (i.e., cytokine storm). Nanodrug delivery systems and nanoparticles are a novel approach to address IAV infections. Herein, UiO-66 nanoparticles (NPs) are synthesized using a high-temperature melting reaction. The in vitro and in vivo optimal concentrations of UiO-66 NPs for antiviral activity are 200 μg mL-1 and 60 mg kg-1, respectively. Transcriptome analysis revealed that UiO-66 NPs can activate the RIG-I-like receptor signaling pathway, thereby enhancing the downstream type I interferon antiviral effect. These NPs suppress inflammation-related pathways, including the FOXO, HIF, and AMPK signaling pathways. The inhibitory effect of UiO-66 NPs on the adsorption and entry of IAV into A549 cells is significant. This study presents novel findings that demonstrate the effective inhibition of IAV adsorption and entry into cells via UiO-66 NPs and highlights their ability to activate the cellular RIG-I-like receptor signaling pathway, thereby exerting an anti-IAV effect in vitro or in mice. These results provide valuable insights into the mechanism of action of UiO-66 NPs against IAV and substantial data for advancing innovative antiviral nanomedicine.

Clinical data mining: challenges, opportunities, and recommendations for translational applications

Clinical data mining of predictive models offers significant advantages for re-evaluating and leveraging large amounts of complex clinical real-world data and experimental comparison data for tasks such as risk stratification, diagnosis, classification, and survival prediction. However, its translational application is still limited. One challenge is that the proposed clinical requirements and data mining are not synchronized. Additionally, the exotic predictions of data mining are difficult to apply directly in local medical institutions. Hence, it is necessary to incisively review the translational application of clinical data mining, providing an analytical workflow for developing and validating prediction models to ensure the scientific validity of analytic workflows in response to clinical questions. This review systematically revisits the purpose, process, and principles of clinical data mining and discusses the key causes contributing to the detachment from practice and the misuse of model verification in developing predictive models for research. Based on this, we propose a niche-targeting framework of four principles: Clinical Contextual, Subgroup-Oriented, Confounder- and False Positive-Controlled (CSCF), to provide guidance for clinical data mining prior to the model's development in clinical settings. Eventually, it is hoped that this review can help guide future research and develop personalized predictive models to achieve the goal of discovering subgroups with varied remedial benefits or risks and ensuring that precision medicine can deliver its full potential.

Impact, healthcare utilization and costs of travel-associated mosquito-borne diseases in international travellers: a prospective study

BACKGROUND

International travellers frequently acquire infectious diseases whilst travelling, yet relatively little is known about the impact and economic burden of these illnesses on travellers. We conducted a prospective exploratory costing study on adult returning travellers with falciparum malaria, dengue, chikungunya or Zika virus.

METHODS

Patients were recruited in eight Travel and Tropical Medicine clinics between June 2016 and March 2020 upon travellers' first contact with the health system in their country of residence. The patients were presented with a structured 52-question self-administered questionnaire after full recovery to collect information on patients' healthcare utilization and out-of-pocket costs both in the destination and home country, and about income and other financial losses due to the illness.

RESULTS

A total of 134 patients participated in the study (malaria, 66; dengue, 51; chikungunya, 8; Zika virus, 9; all fully recovered; median age 40; range 18-72 years). Prior to travelling, 42% of patients reported procuring medical evacuation insurance. Across the four illnesses, only 7% of patients were hospitalized abroad compared with 61% at home. Similarly, 15% sought ambulatory services whilst abroad compared with 61% at home. The average direct out-of-pocket hospitalization cost in the destination country (USD $2236; range: $108-$5160) was higher than the direct out-of-pocket ambulatory cost in the destination country (USD $327; range: $0-$1560), the direct out-of-pocket hospitalization cost at home (USD $35; range: $0-$120) and the direct out-of-pocket ambulatory costs at home (US$45; range: $0-$192). Respondents with dengue or malaria lost a median of USD $570 (Interquartile range [IQR] 240-1140) and USD $240 (IQR 0-600), respectively, due to their illness, whilst those with chikungunya and Zika virus lost a median of USD $2400 (IQR 1200-3600) and USD $1500 (IQR 510-2625), respectively.

CONCLUSION

Travellers often incur significant costs due to travel-acquired diseases. Further research into the economic impact of these diseases on travellers should be conducted.

Lyme borreliosis presenting as severe back pain after Shinrin-Yoku (forest bathing) in southern Germany

Since Lyme borreliosis is endemic in the Northern Hemisphere, it is usually not in the spotlight of travel medicine. However, borreliosis is a relevant problem and diagnostic challenge in travelers from the Southern Hemisphere returning from trips to Europe and North America.

Safety, Immunogenicity, and Effectiveness of Defective Viral Particles Arising in Mast Cells Against Influenza in Mice

Mast cells play pivotal roles in the pathogenesis of influenza A virus (IAV) infections. Defective viral particles (DPs) often arise during IAV replication, which can interfere with the replication of infectious viruses and stimulate the antiviral response of host cells. Therefore, DPs are expected to have immune-protective functions in clinic. However, the potent immunogenicity and effectiveness of DPs arising in mast cells during IAV replication have not been reported. In the present study, we showed that DPs generated in the human mastocytoma cell line HMC-1 following H1N1 infection were safe to mice after vaccination. Compared with lung adenocarcinoma cells, A549, DPs generated in infected mast cells had much better immunostimulatory activity, enhancing both humoral and cellular immunity of hosts. Notably, they could significantly increase the expression of immune-associated cytokines, especially the IFN-γ. Due to the robust immunogenicity, thus DPs generated in infected mast cells could stimulate the robust protective immune reaction effectively to fight against lethal IAV re-challenge after vaccination, which result in the high survival, decreased lung injury as well as inhibition of viral replication and inflammatory response in lungs. This study is the first to illustrate and explore the safety, immunogenicity, and effectiveness of DPs arising in mast cells against influenza as favorable potential vaccination. The results provide insight into the advances of new prophylactic strategies to fight influenza by focusing on DPs generated in mast cells.

Profile and complexity of travel medicine consultations in Chile: unicentric cross-sectional study

OBJECTIVE

To analyse the spectrum, vaccination needs and pretravel advice complexity of travellers presenting at a travel medicine clinic in Santiago, Chile.

DESIGN

Cross-sectional study.

SETTING

Pretravel consultations in a private healthcare centre in Chile, an 'emerging market' country in South America.

PARTICIPANTS

Travellers (n=1341) seeking pretravel advice at the Travel Medicine Program of Clínica Alemana, Santiago, from April 2016 to March 2018.

PRIMARY AND SECONDARY OUTCOME MEASURES

Demographical and travel characteristics, indications for travel vaccines and malaria prophylaxis, and complexity of travel consultations.

RESULTS

Of 1341 travellers, 51% were female; the median age was 33 years. Most frequent travel reasons were tourism (67%) and business (20%). Median travel duration and time to departure were 21 days and 28 days, respectively. Most destinations were located in America (41%), followed by Asia (36%) and Africa (26%); 96% visited less developed countries, mostly in tropical regions, with risk of arboviral infections (94%) and malaria (69%). The indicated vaccine indications comprised hepatitis A (84%), yellow fever (58%), typhoid fever (51%), rabies (29%), polio (8%), Japanese encephalitis (6%) and meningococcal meningitis (5%). More than 60% of consultations were classified as complex.

CONCLUSION

The studied population mostly visited less developed tropical regions, resulting in a high requirement of yellow fever and other travel-related vaccinations. Most consultations were complex and required a comprehensive knowledge and training in travel medicine.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pre-Treatment with Zirconia Nanoparticles Reduces Inflammation Induced by the Pathogenic H5N1 Influenza Virus

Background

New approaches are urgently needed to fight influenza viral infection. Previous research has shown that zirconia nanoparticles can be used as anticancer materials, but their antiviral activity has not been reported. Here, we investigated the antiviral effect of zirconia (ZrO₂) nanoparticles (NPs) against a highly pathogenic avian influenza virus.

Materials and Methods

In this study, the antiviral effects of ZrO₂ on H5N1 virus were assessed in vivo, and the molecular mechanism responsible for this protection was investigated.

Results

Mice treated with 200 nm positively-charged NPs at a dose of 100 mg/kg showed higher survival rates and smaller reductions in weight. 200 nm ZrO₂ activated mature dendritic cells and initially promoted the expression of cytokines associated with the antiviral response and innate immunity. In the lungs of H5N1-infected mice, ZrO₂ treatment led to less pathological lung injury, significant reduction in influenza A virus replication, and overexpression of pro-inflammatory cytokines.

Conclusion

This antiviral study using zirconia NPs shows protection of mice against highly pathogenic avian influenza virus and suggests strong application potential for this method, introducing a new tool against a wide range of microbial infections.

Reducing infectious disease inequities among migrants

BACKGROUND

migration has reached unprecedented levels, with 3.6% of the world's population living outside their country of birth. Migrants comprise a substantial proportion of high-income country populations, are at increased risk of a range of infectious diseases, compared to native-born populations and may experience worse health outcomes due to barriers accessing timely diagnoses and treatment. Poor access to essential healthcare services can be attributed to several factors, including language and cultural barriers and lack of specific inclusive health policies.

METHODS

This review draws on evidence from the immigrant health and travel medicine literature, with a focus on infectious disease risks. It presents strategies to reduce barriers to healthcare access through health promotion and screening programs both at the community and clinic level and the delivery of linguistically and culturally competent care. The Methods: Salud Entre Culturas (SEC) 'Health Between Cultures' project from the Tropical Medicine Unit at the Hospital Ramon y Cajal in Madrid is described as an effective model of care.

RESULTS

For those providing healthcare to migrant populations, the use of community-consulted approaches are considered best practice in the development of health education, health promotion and the delivery of targeted health services. At the clinic-level, strategies optimizing care for migrants include the use of bilingual healthcare professionals or community-based healthcare workers, cultural competence training of all clinic staff, the appropriate use of trained interpreters and the use of culturally appropriate health promotion materials.

CONCLUSIONS

Multifaceted strategies are needed to improve access, community knowledge, community engagement and healthcare provider training to provide appropriate care to migrant populations to reduce infectious disease disparities.

Non-communicable diseases in migrants: an expert review

BACKGROUND

Non-communicable diseases (NCDs) remain a major challenge in the 21st century. High-income countries (HICs) populations are ethnically and culturally diverse due to international migration. Evidence suggests that NCDs rates differ between migrants and the host populations in HICs. This paper presents a review of NCDs burden among migrant groups in HICs in Europe, North America and Australia with a major focus on cardiovascular diseases (CVDs), cancer and diabetes.

METHODS

We performed a narrative review consisting of scholarly papers published between 1960 until 2018.

RESULTS

CVD risk differs by country of origin, country of destination and duration of residence. For example, stroke is more common in sub-Sahara African and South-Asian migrants, but lower in North African and Chinese migrants. Chinese migrants, however, have a higher risk of haemorrhagic stroke despite the lower rate of overall stroke. Coronary heart disease (CHD) is more common in South-Asian migrants, but less common in sub-Saharan and north African migrants although the lower risk of CHD in these population is waning. Diabetes risk is higher in all migrants and migrants seem to develop diabetes at an earlier age than the host populations. Migrants in general have lower rates of overall cancer morbidity and mortality than the host populations in Europe. However, migrants have a higher infectious disease-related cancers than the host populations in Europe. In North America, the picture is more complex. Data from cross-national comparisons indicate that migration-related lifestyle changes associated with the lifestyle of the host population in the country of settlement may influence NCDs risk among migrants in a very significant way.

CONCLUSION

With exception of diabetes, which is consistently higher in all migrant groups than in the host populations, the burden of NCDs among migrants seems to depend on the migrant group, country of settlement and NCD type. This suggests that more work is needed to disentangle the key migration-related lifestyle changes and contextual factors that may be driving the differential risk of NCDs among migrants in order to assist prevention and clinical management of NCDs in these populations.

Spectrum of illness in migrants to Canada: sentinel surveillance through CanTravNet

BACKGROUND

Due to ongoing political instability and conflict in many parts of the world, migrants are increasingly seeking asylum and refuge in Canada.

METHODS

We examined demographic and travel correlates of illnesses among migrants to Canada to establish a detailed epidemiologic framework of this population for Canadian practitioners. Data on ill-returned Canadian travellers presenting to a CanTravNet site between 1 January 2015 and 31 December 2015 were analyzed.

RESULTS

During the study period, 2415 ill travellers and migrants presented to a CanTravNet site, and of those, 519 (21.5%) travelled for the purpose of migration. Sub-Saharan Africa (n = 160, 30.8%), southeast Asia (n = 84, 16.2%) and south central Asia (n = 75, 14.5%) were the most common source regions for migrants, while the top specific source countries, of 98 represented, were the Philippines (n = 45, 8.7%), China (n = 36, 6.9%) and Vietnam (n = 31, 6.0%). Compared with non-migrant travellers, migrants were more likely to have a pre-existing immunocompromising medical condition, such as HIV or diabetes mellitus (P < 0.0001), and to require inpatient management of their illness (P < 0.0001). Diagnoses such as tuberculosis (n = 263, 50.7%), hepatitis B and C (n = 78, 15%) and HIV (n = 11, 2.1%) were over-represented in the migrant population compared with non-migrant travellers (P < 0.0001). Most cases of tuberculosis in the migrant population (n = 263) were latent (82% [n = 216]); only 18% (n = 47) were active.

CONCLUSIONS

Compared with non-migrant travellers, migrants were more likely to present with a communicable infectious disease, such as tuberculosis, potentially complicated by an underlying immunosuppressing condition such as HIV. These differences highlight the divergent healthcare needs in the migrant population, and underscore the importance of surveillance programmes to understand their burden of illness. Intake programming should be adequately resourced to accommodate the medical needs of this vulnerable population of new Canadians.

Zika in travellers 1947-2017: a systematic review

INTRODUCTION

Travellers contributed substantially to the rapid spread of Zika virus (ZIKV). They act as sentinel and may unmask ongoing ZIKV transmission in countries where outbreaks have not yet been reported. Our objectives were to (i) describe the burden of ZIKV infections in international travellers over time; (ii) estimate the proportion of birth defects as a result of maternal ZIKV infection in travellers; (iii) track the extent of sexual transmission; (iv) summarize ZIKV infections in returning travellers as reported by the GeoSentinel network; and (v) identify countries without reports on local ZIKV transmission where travellers served as sentinel.

METHODS

We performed a systematic review from 1947 to April 2017 on travel-associated ZIKV infections. We also compared published reports on autochthonous ZIKV transmission in Asia with published reports on exportations from travellers in Asia.

RESULTS

Of 314 papers that fit the inclusion criteria, 61 were eligible for final analysis. There was an exponential increase in the number of reported ZIKV infected travellers from the years 2013 to 2016, which declined in 2017. Amongst pregnant women with ZIKV infection, (5%) resulted in a fetus or infant with ZIKV-associated birth defects. An estimated 1% of the total number of ZIKV cases reported in the USA and Europe were acquired through sexual transmission. Through the GeoSentinel network, five countries (Indonesia, Philippines, Thailand, Vietnam, Cameroon) were identified as sentinel markers where ZIKV was exported despite the absence of reported local transmission.

CONCLUSIONS

Mobility patterns and travel volumes can help to identify the most likely origin of importation, and also in predicting further propagation. Studies on pregnant returning travellers have contributed to a better understanding of the risk estimates of congenital Zika syndrome/microcephaly as a result of maternal ZIKV infection, and the relative contribution of sexual transmisison.

Infectious disease implications of large-scale migration of Venezuelan nationals

Background

The ongoing economic and political crisis in Venezuela has resulted in a collapse of the healthcare system and the re-emergence of previously controlled or eliminated infectious diseases. There has also been an exodus of Venezuelan international migrants in response to the crisis. We sought to describe the infectious disease risks faced by Venezuelan nationals and assess the international mobility patterns of the migrant population.

Methods

We synthesized data on recent infectious disease events in Venezuela and among international migrants from Venezuela, as well as on current country of residence among the migrant population. We used passenger-level itinerary data from the International Air Transport Association to evaluate trends in outbound air travel from Venezuela over time. We used two parameter-free mobility models, the radiation and impedance models, to estimate the expected population flows from Venezuelan cities to other major Latin American and Caribbean cities.

Results

Outbreaks of measles, diphtheria and malaria have been reported across Venezuela and other diseases, such as HIV and tuberculosis, are resurgent. Changes in migration in response to the crisis are apparent, with an increase in Venezuelan nationals living abroad, despite an overall decline in the number of outbound air passengers. The two models predicted different mobility patterns, but both highlighted the importance of Colombian cities as destinations for migrants and also showed that some migrants are expected to travel large distances. Despite the large distances that migrants may travel internationally, outbreaks associated with Venezuelan migrants have occurred primarily in countries proximate to Venezuela.

Conclusions

Understanding where international migrants are relocating is critical, given the association between human mobility and the spread of infectious diseases. In data-limited situations, simple models can be useful for providing insights into population mobility and may help identify areas likely to receive a large number of migrants.

Expanding travel medicine in the 21st century to address the health needs of the world's migrants

The body of knowledge needed to effectively practice travel medicine has expanded since the 1990s, as migrants begin to comprise an increasing proportion of the world's population. We describe the unique needs of migrants and provide resources available to migration health practitioners. As the number of the world's migrants grows, collaboration across disciplines is key to achieving high-quality migration health practices.