Travellers' profile, travel patterns and vaccine practices--a 10-year prospective study in a Swiss Travel Clinic

Causes of death among international travellers in Peru, 2017 to 2021

BACKGROUND

The wellbeing and safety of international tourists is a paramount concern for governments and stakeholders. Mortality among travellers and the causes of death serve as a significant metric of destination safety. We describe the epidemiology and causes of death among international travellers in Peru.

METHODS

Data retrieved from the Peruvian government's deaths certificates registry included all non-residents who died between January 2017 and December 2021. We analysed the national incidence and causes of death among international travellers in Peru. Causes of death were classified into non-communicable diseases (NCD), communicable diseases and injuries. We classified fatalities according to the existence of preventive measures that could be provided during the travel medicine consultation to decrease the risk.

RESULTS

We obtained records from 1514 deaths among international travellers (973 males, 64%). The incidence increased from 0.2 deaths per 10 000 travellers in 2017 to 9.9 in 2021. NCDs were the most common causes of death (n = 560, 37%), followed by communicable diseases (n = 487, 32%), and injuries (n = 321, 21%). Causes of death were unknown in 9.7% of the records. The leading causes of death in these categories were cancer, cardiovascular disease, COVID-19 and trauma. We found similar sex distribution of NCDs in travellers aged >50 years and higher rates of communicable diseases among males across all ages. Injury-associated deaths were significantly higher among males aged 18-29 years (P < 0.001) compared with other sex-age groups. We estimated that for 57.7% of deaths risk could have been decreased through pre-travel advice.

CONCLUSION

Rates of deaths among travellers to Peru increased over time. Most deaths were due to NCDs, followed by communicable diseases and injuries. Pre-travel medical optimization and effective advice focused on age-sex and destination specific risks could reduce risk among travellers. Increased awareness among travel medicine practitioners and improvement of emergency medical response systems in Peru could decrease mortality.

Travel vaccines-priorities determined by incidence and impact

BACKGROUND

Infectious disease epidemiology is continuously shifting. While travel has been disrupted by the COVID-19 pandemic and travel-related epidemiological research experienced a pause, further shifts in vaccine-preventable diseases (VPDs) relevant for travellers have occurred.

METHODS

We conducted a literature search on the epidemiology of travel-related VPD and synthesized data for each disease with a focus on symptomatic cases and on the impact of the respective infection among travellers, considering the hospitalization rate, disease sequela and case fatality rate. We present new data and revised best estimates on the burden of VPD relevant for decisions on priorities in travel vaccines.

RESULTS

COVID-19 has emerged to be a top travel-related risk and influenza remains high in the ranking with an estimated incidence at 1% per month of travel. Dengue is another commonly encountered infection among international travellers with estimated monthly incidence of 0.5-0.8% among non-immune exposed travellers; the hospitalized proportion was 10 and 22%, respectively, according to two recent publications. With recent yellow fever outbreaks particularly in Brazil, its estimated monthly incidence has risen to >0.1%. Meanwhile, improvements in hygiene and sanitation have led to some decrease in foodborne illnesses; however, hepatitis A monthly incidence remains substantial in most developing regions (0.001-0.01%) and typhoid remains particularly high in South Asia (>0.01%). Mpox, a newly emerged disease that demonstrated worldwide spread through mass gathering and travel, cannot be quantified regarding its travel-related risk.

CONCLUSION

The data summarized may provide a tool for travel health professionals to prioritize preventive strategies for their clients against VPD. Updated assessments on incidence and impact are ever more important since new vaccines with travel indications (e.g. dengue) have been licensed or are undergoing regulatory review.

Travelers and travel vaccines at six health care systems in the Vaccine Safety Datalink

BACKGROUND

Studying the safety of travel vaccines poses challenges since recipients may be traveling during the risk window for adverse events and the identification of a suitable comparison group can also be difficult. The examination of traveler characteristics, travel vaccination patterns, and health care utilization using electronic health record (EHR) data can inform the feasibility of future travel vaccine safety studies.

METHODS

A retrospective cohort study of health plan members in the Vaccine Safety Datalink Project aged 9 months and older who had a travel-related encounter or received a travel vaccine from 2009 to 2018 was performed. Travel regions visited, travel duration, type of travel vaccine received (typhoid, yellow fever, Japanese encephalitis, rabies, and cholera), and timing of vaccination date before departure date were described. Sociodemographic information, clinical characteristics, and health care utilization were compared between travelers who received travel vaccines and travelers who did not.

RESULTS

A total of 1,026,822 unique travelers departing from the United States were identified; 612,795 travelers received 898,196 doses of travel vaccines. The most commonly administered travel vaccine was typhoid vaccine and 77% of all travel vaccines were given more than one week prior to departure. Compared with travelers without travel vaccines, travelers with travel vaccines were overall similar but as a group were slightly younger, healthier, and had lower Hispanic representation. Health care utilization dramatically decreased during travel. Outpatient visits decreased from 294.8 visits per 10,000 person-days before travel to 24.2 visits per 10,000 person-days during reported travel dates.

CONCLUSIONS

Through the EHR information from almost a million travelers, a departure date and duration of travel were successfully captured for the majority of travelers with corresponding health care utilization data. Time after vaccination and prior to departure can potentially be used in the future to compare travelers who receive travel vaccines with travelers who do not receive travel vaccines when looking at adverse events of interest after vaccination.

Characteristics and potential quality indicators for evaluating pre-travel consultations in Japan hospitals: the Japan Pretravel consultation registry (J-PRECOR)

BACKGROUND

Awareness of pre-travel consultations (PTCs) and prevention methods for overseas travel-related diseases, and the understanding of PTCs among Japanese travelers and medical professionals remains low in Japan. A multicenter registry was established to examine PTCs in Japan. This study assessed the PTC implementation rate and examined the indicators of PTCs that can be used as criteria for evaluating quality.

METHODS

Clients who presented for their PTCs at 17 facilities and were registered between February 1, 2018, and May 31, 2020, were included. Medical information was extracted retrospectively via a web-based system. Correlations between vaccination risk categories and advice/intervention proportions by the facility were evaluated using Spearman's ordered phase relations (α = 0.05).

RESULTS

Of the 9700 eligible clients (median age, 32 years; 880 [9.1%] aged < 16 years and 549 [5.7%] aged ≥65 years), the most common travel duration was ≥181 days (35.8%); higher among younger clients. The most common reason for travel was business (40.5%); the US (1118 [11.5%]) and Asia (4008 [41.3%]) were the most common destinations and continents, respectively. The vaccine number (median three per person) increased after the PTCs except for the tetanus toxoid. Only 60.8% of the clients recommended for malaria prophylaxis received anti-malarial agents. The gross national income; the incidence of human rabies, typhoid fever, falciparum malaria; and dengue risk category were associated with the percentage of hepatitis-A vaccines; explaining rabies post-exposure prophylaxis, typhoid-fever vaccinations, malaria-prophylaxis prescriptions; and mosquito repellants, respectively.

CONCLUSIONS

Although the characteristics of the travelers differed, the quality of the PTCs should be improved to address, for example, the lower rate of acceptance of malaria prophylaxis in Japan.

If I told you that there is no need for yellow fever vaccine booster would you still come to the travel clinic?: a cross-sectional study

Background

Yellow Fever (YF) immunization required a single dose vaccine with boosters every 10 years. After International Health Regulation (IHR) amendment annex 7 (July 2016), it was accepted that a single dose confers lifelong immunity. Since pre-travel advice is as important as vaccination when traveling, it is essential to clarify why travelers come to a travel health consultation, with the possibility of IHR amendment having a negative impact on travelers’ health. This study aims to describe travelers’ reasons to come to a pre-travel consultation in Lisbon and if they would return if they wouldn’t need the YF vaccine booster.

Methods

An observational cross-sectional study was conducted during 5 months in the waiting room of Instituto de Higiene e Medicina Tropical travel clinic in Lisbon, Portugal. Travelers were asked about sociodemographic characteristics, destination country, travel duration and reasons to travel in an anonymous self-administered questionnaire.

Results

A total of 1043 travelers agreed to participate in the study. Although 61.0% (627/1028) did not come to the clinic to get the YF vaccine, from those who did, 36.7% (133/362) would not come and 12.9% (47/362) didn’t knew if they would come if the vaccine would not be necessary.

Conclusion

The IHR amendment may have a negative impact on travel clinic attendance and on travelers´ health.

Morbidity among Israeli backpack travelers to tropical areas

BACKGROUND

Travelers to tropical areas may be susceptible to illness or injuries. This study aims to assess morbidity among travelers during their travel and compare those who became ill or were injured with those who did not.

METHODS

This prospective study included 400 travelers who were counselled by a physician in pre-travel clinics in central Israel between 2017 and 2018. Participants were interviewed within a month after their return regarding morbidity during travel, including health problems that started one week following their return.

RESULTS

Most travelers (N = 320, 80%) reported at least one illness or injury. Illnesses/injuries were more common among females than males (84.9% vs. 75.1%, p = 0.01), travel periods longer than 30 days (87.7% vs. 77.2%, p = 0.03), and travelers accompanied by their friends or solo travelers compared with those who traveled with their family/partner (83.8% and 70.0%, respectively, p = 0.002). The most common complaint was diarrhea (N = 159, 49.6%), followed by high-altitude sickness (N = 118, 36.9%) and fever (N = 100, 31.2%). Altitude sickness symptoms were more common in females than in males (58.9% vs. 41.0%, p = 0.006) and in those who ascended rapidly in comparison to those who ascended gradually (58.7% vs. 44.6%, p = 0.04). Animal injury was reported by 30 (7.5%) participants yet only eight (27.0%) received medical care, seven of whom (23.3%) were vaccinated against rabies.

CONCLUSIONS

Being a female, traveling with friends or alone and longer travel periods were associated with illness/injury. Practitioners at pre-travel clinics should inform travelers of the possible risks including the potential severe consequences of rabies and altitude sickness.

Catch-up immunization for adolescents and young adults during pre-travel consultation in Japan

Rubella and measles outbreaks in adults occur because of unimmunized or partially immunized status. Travel clinics play an important role in catch-up measles, rubella, mumps, and varicella immunization for adults. We evaluated the need for catch-up measles, rubella, mumps, and varicella immunization by young adults at our travel clinic. This retrospective observational study was conducted at the National Center for Global Health and Medicine from June 1, 2017 to May 31, 2018. Adults aged 16-49 years who received pre-travel consultation and had childhood immunization records were included. Individuals who fully or partially received planned measles, rubella, mumps, and varicella catch-up immunization were classified as "immunized." We calculated the proportion of "immunized" individuals and analyzed the factors associated with catch-up measles, rubella, mumps, and varicella immunization at pre-travel consultation using logistic regression analysis. Overall, 3,456 individuals received pre-travel consultations during the study period; 827 (336 men, median age 22 years) had childhood immunization records. The most common trip purposes were study (33%) and tourism (24%). The most common destination was Asia (39%). Catch-up immunization of any measles, rubella, mumps, and varicella vaccine was needed by 755 individuals. After consultation, 20-46% of these participants who needed catchup immunization received at least one dose of immunization. Factors that are negatively associated with measles, rubella, mumps, and varicella catch-up immunization were tourism (odds ratio 0.37 to 0.58), yellow fever vaccination (0.45 to 0.50) (excluding varicella), and each disease history (0.13 to 0.40) (excluding rubella and varicella). Further studies are needed to identify barriers to catch-up immunization.

Beyond fragmentary: A proposed measure for travel vaccination concerns

The travel medicine literature points to travelers' concerns as significant promoters of their under-vaccinations. Therefore, this study researches the hitherto understudied concept of vaccination concern and its theoretical scope in the international travel space. It attempts a conceptualization of the concept by delimiting its theoretical scope and proposes a measure for it. An exploratory sequential mixed-methods design was used to conduct four interlocking studies using data from a netnography, field interviews, and surveys among varied international travelers. A scale with six dimensions, comprising safety, efficacy, cost, time, access, and autonomy concerns were revealed. The scale significantly explained mainstream and segments-based tourists' uptake attitudes and behavior for their eligible vaccines. The findings suggest that anti-travel vax sentiments and public vax sentiments despite conceptually similar are considerably distinct. The broad nature of the scale and its prediction of travelers' vaccine uptake make it clinically relevant for tracking and resolving concerns for increased vaccine uptake.

Travel-Related Typhoid Fever: Narrative Review of the Scientific Literature

Enteric fever is a foodborne infectious disease caused by Salmonella enterica serotypes Typhi and Paratyphi A, B and C. The high incidence in low income countries can increase the risk of disease in travelers coming from high income countries. Pre-travel health advice on hygiene and sanitation practices and vaccines can significantly reduce the risk of acquiring infections. Although the majority of the cases are self-limiting, life-threatening complications can occur. Delayed diagnosis and cases of infections caused by multi-drug resistant strains can complicate the clinical management and affect the prognosis. More international efforts are needed to reduce the burden of disease in low income countries, indirectly reducing the risk of travelers in endemic settings. Surveillance activities can help monitor the epidemiology of cases caused by drug-susceptible and resistant strains.

Characteristics and preparation of the last-minute traveler: analysis of vaccine usage in the Global TravEpiNet Consortium

BACKGROUND

Last-minute travellers (LMTs) present challenges for health care providers because they may have insufficient time for recommended vaccinations or pre-travel preparation. Our objective was to obtain a better understanding of LMTs in order to help travel medicine providers develop improved strategies to decrease the number of LMTs and potentially reduce travel-related morbidity.

METHODS

We defined LMTs as travellers with a departure date of 7 days or fewer from the medical encounter. We analysed the characteristics and health preparation of 12 494 LMTs who presented to a network of US clinical practices for pre-travel health advice between January 2009 and December 2015.

RESULTS

LMTs comprised 16% of all travellers. More LMTs than non-LMTs travelled for business or to visit friends and relatives (VFR) (26% vs 16% and 15% vs 8%, respectively; P < 0.0001). More LMTs also travelled for longer than 1 month (27% vs 21%; P < 0.0001) and visited only urban areas (40% vs 29%; P < 0.0001). At least one travel vaccine was deferred by 18% of LMTs because of insufficient time before departure. Vaccines that required multiple vaccinations, such as Japanese encephalitis and rabies, were the most likely to be deferred because of time constraints.

CONCLUSION

Interventions to improve the timing of pre-travel health consultations should be developed, particularly for business and VFR travellers. Recently endorsed accelerated vaccine schedules for Japanese encephalitis and rabies may help some LMTs receive protection against these infections despite late presentation for pre-travel health care.

Determinants of Compliance of Travelers with Vaccination and Malaria Prophylaxis at a Travel Clinic

BACKGROUND

Pre-travel medical consultation is essential to reduce health impairment during travel. Yellow fever vaccination (YFV) is mandatory to enter some endemic countries. In this study, we evaluated the factors that affect compliance with appropriate prevention of infectious diseases in travelers who visited clinic for YFV.

METHODS

For this retrospective study, chart reviews for 658 patients who visited a travel clinic for YFV before travel were conducted. The period of this study was from January 2016 to September 2018. The associations between appropriate vaccination and factors such as travel duration, destination, time of visiting clinic before departure, and purpose of travel were analyzed.

RESULTS

Among 658 patients who got YFV during the study period, 344 patients (52.3%) received additional vaccination or malaria prophylaxis following a physician's recommendation. Travelers who visited the clinic more than 21 days before departure were more compliant than those who visited 14 days or fewer before departure (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.23-2.93; P = 0.004). Travelers visiting Africa were more compliant than were those traveling to South and Central America (OR, 1.97; 95% CI, 1.34-2.90; P = 0.001). Travelers in age groups of 40-49 years and over 70 years were less compliant than the 18-29 years old population (OR, 0.51; 95% CI, 0.28-0.93; P = 0.027 and OR, 0.19; 95% CI, 0.04-0.84; P = 0.03, respectively). Also, those who traveled for tour or to visit friends or relatives were more compliant than those who departed for business (OR, 0.77; 95% CI, 1.03-3.56; P = 0.04).

CONCLUSION

For appropriate vaccination, pre-travel consultation at least 3 weeks before departure is crucial. Travelers should be aware of required vaccination and malaria prophylaxis before visiting South and Central America and Asia. Plans to enhance compliance of the elderly and business travelers should be contrived.

Stand-by emergency treatment (SBET) of malaria in Spanish travellers: a cohort study

Background

Among strategies for malaria prevention, stand-by emergency treatment (SBET) is a possible approach, but scarce evidences exists investigating travellers’ adherence and behaviours toward its use; therefore, the presented study aimed to determine travellers’ compliance toward the SBET when prescribed in travel clinics.

Methods

A prospective cohort study was performed at the Travel Health Clinic of the Hospital Universitari de Bellvitge, Barcelona, Spain, during 2017. The research was planned on survey-based design, using pre- and post-travel questionnaires.

Results

In the study period, of 5436 subjects who attended the HUB Travel Medicine Clinic, 145 travellers to malaria-endemic areas were prescribed SBET, and all patients agreed to participate in the study by completing the pre-travel questionnaire. Approximately half the participants were women (n = 75, 51.7%), and the median age of all travellers was 29 years (range 13–57), mainly travelling to South-East Asia (n = 69, 47.6%), with Indonesia and the Philippines as the most popular destinations. The length of travels had a median duration of 29 days (range 10–213). Of the recruited participants, 98 replied to the online post-travel survey, reaching a response rate of 67.6%. A total of 62.2% of travellers to which SBET was prescribed did not buy and carry drugs while travelling abroad. No participants’ baseline or travel characteristic was shown to be significantly associated (p > 0.05) with this behaviour. Four women (4.1%) experienced fever and self-administered SBET, without seeking medical attention. No malaria cases were observed.

Conclusions

This cohort study addressed travellers’ adherence and behaviour toward SBET, highlighting an incorrect use of the emergency treatment in case of presumptive malaria symptoms. This should be taken into account during pre-travel consultation, since the success of this strategy for malaria prevention depends on travellers’ strong adherence to it.

German travelers' preferences for travel vaccines assessed by a discrete choice experiment

BACKGROUND

Many travelers to regions with endemic infectious diseases do not follow health authorities' recommendations regarding vaccination against vaccine-preventable infectious diseases, before traveling. The determinants of individual travelers' decisions to vaccinate before traveling are largely unknown. This study aimed to provide this information using a discrete choice experiment (DCE) administered to four types of German travelers: (1) business travelers; (2) travelers visiting friends and relatives (VFR); (3) leisure travelers; and (4) backpackers.

METHODS

A DCE survey was developed, pretested and administered online. It included a series of choice questions in which respondents chose between two hypothetical vaccines, each characterized by four disease attributes with varying levels describing the of risk, health impact, curability and transmissibility of the disease they would prevent (described with four disease attributes with varying levels of risk, health impact, curability and transmissibility), and varying levels of four vaccine attributes (duration of protection, number of doses required, time required for vaccination, and vaccine cost). A random-parameters logit model was used to estimate the importance weights each traveler type placed on the various attribute levels. These weights were used to calculate mean monetary equivalents (MMEs) of changes in each attribute (holding all others constant) and of hypothetical disease-vaccine combinations.

RESULTS

All traveler types' choices indicated that they attached the greatest importance to the risk and health impact of disease and to the vaccine cost whereas the other disease and vaccine attributes were less important for their decisions about travel vaccines. An option of not choosing any of the vaccine-pairs presented was rarely selected indicating that travelers' generally prefer to be vaccinated rather than not. The MMEs of changes in vaccine attributes indicated a very high variability between the individual travelers within each type.

CONCLUSIONS

The travelers' responses indicated strong preferences for selecting vaccination rather than opting out of vaccination, and disease risk, health impact and vaccine cost were the most important features for vaccine choice.

Response to fever and utilization of standby emergency treatment (SBET) for malaria in travellers to Southeast Asia: a questionnaire-based cohort study

Background

Guidelines in several European countries recommend standby emergency treatment (SBET) for travellers to regions with low or medium malaria transmission instead of continuous chemoprophylaxis: travellers are advised to seek medical assistance within 24 h in case of fever and to self-administer SBET only if they are not able to consult a doctor within the time period specified. Data on healthcare-seeking behaviour of febrile travellers and utilization of SBET is however scarce as only two studies were performed in the mid-1990s. Since tourism is constantly increasing and malaria epidemiology has dramatically changed in the meantime more knowledge is urgently needed.

Methods

Some 876 travellers to destinations in South and Southeast Asia with low or medium malaria transmission were recruited in the travel clinic of the University Medical Center Hamburg-Eppendorf. Demographic and travel-related data were collected by using questionnaires. Pre-travel advice was carried out and SBET was prescribed in accordance to national guidelines. Post-travel phone interviews were performed to assess health incidents during travel and individual responses of travellers to febrile illness.

Results

Out of 714 patients who were monitored, 130 (18%) reported onset of fever during travel or 14 days after return. Of those travellers who reported fever, 100 (80%) carried SBET during travel. The vast majority of 79 (79%) febrile travellers who carried SBET did not seek medical assistance. Overall, 14 (14%) febrile patients who carried SBET and six (20%) patients who did not carry SBET took the correct measure (doctor visit or timely SBET administration) as a response to febrile illness, respectively. Only two travellers self-administered SBET, but both of them applied the wrong regimen.

Conclusions

In view of declining malaria transmission and improving medical infrastructure in most countries of Southeast Asia and obvious obstacles concerning SBET as shown in this study the current strategy should be re-evaluated. Pre-travel advice concerning malaria in SEA should focus on appropriate mosquito bite protection and clearly emphasize the need to see a doctor within 24 h after onset of fever.