Multicenter EuroTravNet/GeoSentinel study of travel-related infectious diseases in Europe

Infectious diseases and predominant travel-related syndromes among long-term expatriates living in low-and middle- income countries: a scoping review

Introduction

Expatriates working in low-and middle-income countries have unique health problems. Migration leads not only to an increase in individual health risk but also a risk of global impact, such as pandemics. Expatriates with no prior experience living in tropical settings have expressed greatest concern about infectious diseases and appropriate peri-travel consultation is essential to expatriates. The objective of this review is to describe infections and travel-related syndromes among expatriates living in low-and middle-income countries.

Methods

MEDLINE database since the year 2000 was searched for relevant literature. Search terms were “long-term travel”, “expatriate”, and “health problems”. The additional references were obtained from hand-searching of selected articles.

Results

Up to 80% of expatriates suffered from gastrointestinal problems followed by dermatologic problems (up to 40%), and febrile systemic infection/vector-borne/parasitic infection (up to 34%) Expatriates living in Southeast Asia were at risk of vector-borne diseases including dengue and non-Plasmodium falciparum (pf) malaria while expatriates living in South Asia had a high prevalence of acute and chronic diarrhea. Staying long-term in Africa was related to an elevated risk for pf malaria and gastrointestinal infection. In Latin America, dermatologic problems were commonly reported illnesses among expatriates.

Conclusion

Certain health risks for expatriates who are going to depart to specific regions should be the focus of pre-travel consultation. Specific health preparations may reduce the risk of disease throughout their time abroad. Disease and symptom awareness is essential for screening, early diagnosis, and better health outcomes for ill-expatriates.

Immunogenicity of a single fractional intradermal dose of Japanese encephalitis live attenuated chimeric vaccine

BACKGROUND

Japanese encephalitis (JE) is endemic in Asia and the western Pacific. Vaccination is recommended for travellers to endemic regions, but the high cost of the vaccine is a major barrier to uptake.

METHODS

A quasi-experimental, pre-post intervention clinical trial without a control group was conducted to assess the immunogenicity and safety of intradermal (ID) JE vaccine. Healthy adults (18-45 years) received one dose of 0.1 mL (20% of standard dose) ID Imojev® (JE live attenuated chimeric vaccine, Sanofi-Aventis). Adverse events following immunisation (AEFIs) were recorded 10 days post-vaccination. Blood samples were collected at baseline, 4, and 8 weeks post-vaccination. Neutralising antibodies were measured using 50% plaque reduction neutralisation test (PRNT50). Seroconversion was defined as PRNT50 titre ≥10. An in vitro study was also conducted to quantify the rate of decay of vaccine potency after reconstitution.

RESULTS

51 participants (72.6% females, median age 31 years), all non-reactive to JE virus at baseline were enrolled. Mild and moderate AEFIs were reported by 19.6% of participants; none required medical attention or interfered with normal daily activities. All participants seroconverted at 4 weeks (GMT 249.3; 95%CI:192.8-322.5) and remained seropositive at 8-weeks (GMT 135.5; 95%CI:104.5-175.6). Vaccine potency declined at a rate of 0.14 log plaque-forming units/0.5 mL per hour.

CONCLUSIONS

In healthy adults, a single 0.1 mL ID dose of Imojev was safe and immunogenic, at least in the short-term. Reconstituted vials of Imojev vaccine may not retain their potency after 6 hours. Fractional JE ID vaccination could be a cheaper yet effective alternative for short-term travellers. Further studies need to investigate the immune response in a wider age range of individuals and the long-term immunogenicity of fractional JE ID vaccines.

CLINICAL TRIALS REGISTRATION

ACTRN12621000024842.

Attitudes, practices, and obstacles towards influenza vaccination for international travelers among travel health advisors in Germany: A questionnaire-based survey

BACKGROUND

Influenza is the most frequent vaccine-preventable infection in travelers, and both national and international guidelines recommend considering seasonal influenza vaccination (SIV) not only for those with risk factors for complications but for all travelers. However, vaccination coverage may be hampered by a lack of awareness among travelers and health care providers and limited vaccine availability outside the local influenza season.

METHODS

We identified travel health advisors in databases of German medical professional societies and invited them to complete an online questionnaire between April and May 2021.

RESULTS

Among 1085 travel health advisors contacted by email, 253 (23.3%) completed the online questionnaire. Most of them recommend SIV for travelers older than 60 years or those with comorbidities regardless of the travel destination or the influenza season in Germany. However, only very few respondents stated that they had regular access to SIV in June (n = 16, 6.5%), July (n = 10, 4.0%), and August (n = 17, 6.9%), respectively. While most participants (n = 197, 79.4%) stated that they would vaccinate more travelers if they had SIV regularly available outside the German influenza season, only eleven respondents (4.4%) have previously ordered SIV produced for the southern hemisphere, which was attributed mainly to logistic barriers.

CONCLUSIONS

Travel health advisors in Germany recommend SIV for a considerable proportion of travelers. While most of them see a necessity to vaccinate throughout the year, availability of SIV outside the German season is very limited. Current organizational barriers must be overcome to increase vaccination coverage among international travelers.

New Developments in PCR-Based Diagnostics for Bacterial Pathogens Causing Gastrointestinal Infections-A Narrative Mini-Review on Challenges in the Tropics

The application of modern PCR approaches for the diagnosis of bacterial gastrointestinal pathogens is on the rise due to their rapidly available results combined with high sensitivity. While multiple studies describe the ongoing implementation of this technique for routine diagnostic purposes in laboratories in Western industrialized countries, reports on successful and also sustainable respective approaches in resource-poor tropical settings are still scarce. In order to shed light on potential reasons for this marked discrepancy, this narrative review summarizes identified challenges for the application of diagnostic PCR targeting bacterial gastrointestinal pathogens from stool samples in the tropics. The identified and discussed issues comprise the lack of generally accepted definitions for (1) minimum standards regarding sample acquisition, storage and transport time for diagnostic PCR analyses in the tropics, (2) nucleic acid extraction standards allowing an optimum detection of all types of pathogens which may be responsible for gastroenteritis in the tropics, (3) validation standards to ensure comparable quality of applied diagnostic assays, and (4) cut-offs for a reliable discrimination of infection and mere colonization in areas where semi-immunity due to repeated exposition associated with poor hygiene conditions has to be expected. Further implementation research is needed to solve those issues.

An Investigation of the General Population's Self-Reported Hand Hygiene Behaviour and Compliance in a Cross-European Setting

Every year, thousands of people from the UK travel to other countries for work and leisure. Europe, and particularly Spain, is one of the most popular travel destinations for people from the UK. However, it is known that travel to other countries can enhance the risk of communicable disease transmission from person to person, especially when a new one emerges. Adequate hand hygiene behaviour and compliance is widely accepted as being a simple, effective method in preventing the spread of communicable diseases that may be contracted during travel abroad. There is a well-established body of work investigating hand hygiene practice and compliance in community settings, but no recent studies have examined the hand hygiene practice and compliance of the general population when travelling abroad or in a cross-European context. The findings of this study indicated that most UK members of the general population when travelling abroad have a good level of understanding of the importance of adequate hand hygiene practice and compliance and its role regarding communicable disease prevention and control. As such, self-reported levels of compliance were high. Similar findings were made for Spanish members of the general population. However, while self-reported perceptions of adequacy of hand hygiene performance were relatively high, particularly among UK respondents, this was not supported by responses specifically focused on hand hygiene behaviour. However, differences in self-reported adequacy regarding the importance of handwashing versus hand drying, the number of steps that should be followed and the length of time that should be spent washing and drying hands were found for each group. This suggests that self-reported compliance may reflect intention to practice hand hygiene rather than true compliance. It also suggests that there are gaps in knowledge regarding the adequate method of hand hygiene among the cohort as a whole, and indeed these differences may account be a factor in for the high transmission rates of communicable disease when travelling abroad.

Travel-related infections presenting in Europe: A 20-year analysis of EuroTravNet surveillance data

Background

Disease epidemiology of (re-)emerging infectious diseases is changing rapidly, rendering surveillance of travel-associated illness important.

Methods

We evaluated travel-related illness encountered at EuroTravNet clinics, the European surveillance sub-network of GeoSentinel, between March 1, 1998 and March 31, 2018.

Findings

103,739 ill travellers were evaluated, including 11,239 (10.8%) migrants, 89,620 (86.4%) patients seen post-travel, and 2,880 (2.8%) during and after travel. Despite increasing numbers of patient encounters over 20 years, the regions of exposure by year of clinic visits have remained stable. In 5-year increments, greater proportions of patients were migrants or visiting friends and relatives (VFR); business travel-associated illness remained stable; tourism-related illness decreased. Falciparum malaria was amongst the most-frequently diagnosed illnesses with 5,254 cases (5.1% of all patients) and the most-frequent cause of death (risk ratio versus all other illnesses 2.5:1). Animal exposures requiring rabies post-exposure prophylaxis increased from 0.7% (1998–2002) to 3.6% (2013–2018). The proportion of patients with seasonal influenza increased from zero in 1998–2002 to 0.9% in 2013–2018. There were 44 cases of viral haemorrhagic fever, most during the past five years. Arboviral infection numbers increased significantly as did the range of presenting arboviral diseases, dengue and chikungunya diagnoses increased by 2.6% and 1%, respectively.

Interpretation

Travel medicine must adapt to serve the changing profile of travellers, with an increase in migrants and persons visiting relatives and friends and the strong emergence of vector-borne diseases, with potential for further local transmission in Europe.

Funding

This project was supported by a cooperative agreement (U50CK00189) between the Centers for Disease Control and Prevention to the International Society of Travel Medicine (ISTM) and funding from the ISTM and the Public Health Agency of Canada.

Epidemiology of imported infectious diseases, China, 2014-18

BACKGROUND

The frequent movement of population between countries brings an increasing number of travel-related infections. This study aims to define the spectrum and dynamics of imported infections observed from international travel in the Chinese mainland.

METHODS

Sick travellers were screened by inbound sentinel surveillance and post-travel clinic visits from 2014 to 18. The infections were classified as respiratory, gastrointestinal, vector-borne, blood/sexually transmitted and mucocutaneous. The analysed variables included the place of origin of the travellers (Chinese or foreign) and the time when travel-related infection was present (at the time of return, during travel and post-travel visits to the clinic).

RESULTS

In total, 58 677 cases were identified amongst 1 409 265 253 travellers, with an incidence of 41.64/million, comprising during-travel incidence of 27.44/million and a post-travel incidence of 14.20/million. Respiratory infections constituted the highest proportion of illnesses during travel (81.19%, 31 393 of 38 667), which mainly came from Asian countries and tourists; with influenza virus and rhinovirus infections being mainly diagnosed. Vector-borne diseases constituted the highest proportion of post-travel illnesses (98.14%, 19 638 of 20 010), which were mainly diagnosed from African countries and labourers; with malaria and dengue fever being mainly diagnosed. The differential infection spectrum varied in terms of the traveller's demography, travel destination and travel purpose. As such, a higher proportion of foreign travellers had blood/sexually transmitted diseases (89.85%, 2832 of 3152), while Chinese citizens had a higher prevalence of vector-borne diseases (85.98%, 19 247 of 22 387) and gastrointestinal diseases (79.36%, 1115 of 1405). The highest incidence rate was observed amongst travellers arriving from Africa, while the lowest was observed amongst travellers arriving from Europe.

CONCLUSIONS

The findings might help in preparing recommendations for travellers and also aid in primary care or other clinics that prepare travellers before trips abroad. The findings will also help to identify locations and the associated types of infections that might require attention.

A Prospective Study on the Impact and Out-of-Pocket Costs of Dengue Illness in International Travelers

Although the costs of dengue illness to patients and households have been extensively studied in endemic populations, international travelers have not been the focus of costing studies. As globalization and human travel activities intensify, travelers are increasingly at risk for emerging and reemerging infectious diseases, such as dengue. This exploratory study aims to investigate the impact and out-of-pocket costs of dengue illness among travelers. We conducted a prospective study in adult travelers with laboratory-confirmed dengue and recruited patients at travel medicine clinics in eight different countries from December 2013 to December 2015. Using a structured questionnaire, we collected information on patients and their health-care utilization and out-of-pocket expenditures, as well as income and other financial losses they incurred because of dengue illness. A total of 90 patients participated in the study, most of whom traveled for tourism (74%) and visited countries in Asia (82%). Although 22% reported hospitalization and 32% receiving ambulatory care while traveling, these percentages were higher at 39% and 71%, respectively, after returning home. The out-of-pocket direct and indirect costs of dengue illness were US$421 (SD 744) and US$571 (SD 1,913) per episode, respectively, averaging to a total out-of-pocket cost of US$992 (SD 2,052) per episode. The study findings suggest that international travelers incur important direct and indirect costs because of dengue-related illness. This study is the first to date to investigate the impact and out-of-pocket costs of travel-related dengue illness from the patient's perspective and paves the way for future economic burden studies in this population.

Malaria

Malaria is a significant cause of morbidity and mortality throughout the world, and environmental changes are likely to increase its importance in the coming years. Diagnosing this disease is difficult and requires a high index of suspicion, especially in non-endemic countries. Critical care providers play a major role in treating severe malaria and its complications, which has management particularities that might not be readily apparent. Fluid resuscitation should be carefully tailored to avoid complications, and dysperfusion seems more related to degree of parasitemia than hypovolemia. Antimalarial agents are effective, but resistance is growing. Complications can be found in nearly every organ, including cerebral malaria, acute respiratory distress syndrome, and acute kidney injury. As such, a critical care unit is frequently required for organ support when they appear. Superimposed infections are not infrequent. Despite all of this, mortality is encouragingly low with a timely diagnosis and access to appropriate treatment.

Travelers' Diarrhea in Thailand: A Quantitative Analysis Using TaqMan® Array Card

Background

Travelers' diarrhea (TD) is a common illness experienced by travelers from developed countries who visit developing countries. Recent questionnaire-based surveillance studies showed that approximately 6%-16% of travelers experienced TD while visiting Thailand; however, a majority of TD information was limited mainly to US military populations.

Methods

A TD surveillance study was conducted at Bumrungrad International Hospital in 2012-2014 in Bangkok, Thailand. Enteropathogens were identified using conventional methods and the TaqMan® array card (TAC), which uses real-time polymerase chain reaction for the simultaneous detection of multiple pathogens. Analyses to determine pathogen-disease and symptoms association were performed to elucidate the clinical relevance of each enteropathogen.

Results

TAC identified more pathogens per sample than conventional methods. Campylobacter spp. were the most prevalent, followed by the diarrheagenic Escherichia coli and norovirus GII. These agents had significant pathogen-disease associations as well as high attributable fractions among diarrheal cases. A wide range of pathogen loads for Campylobacter spp. was associated with TD, while heat-labile toxin enterotoxigenic Escherichia coli was associated with an increased pathogen load. Most cases were associated with inflammatory diarrhea, while Campylobacter spp. and Shigella spp. were associated with dysentery.

Conclusions

A pan-molecular diagnostic method such as TAC produces quantifiable and comparable results of all tested pathogens, thereby reducing the variability associated with multiple conventional methods. This allows better determination of the clinical relevance of each diarrhea etiologic agent, as well as their geographical relevance in Thailand.

Assessment of fever in the returning traveller

Evaluation of people returning from trips abroad with fever is an important skill for all general physicians given the increasing trend in foreign travel. This evaluation should comprise a detailed travel history, thorough clinical examination, appropriate initial tests and a knowledge of when to ask for further advice. An understanding of the incubation periods of common imported infections and a syndromic approach to patients' symptoms is helpful in order to narrow down the likely diagnosis. The need to implement relevant infection control precautions has been highlighted by the recent Middle East respiratory syndrome coronavirus and Ebola virus disease outbreaks.

NECESSITY TO IMPROVE THE EMERGENCY DIAGNOSTICS OF TICK-BORNE INFECTIONS IN PEOPLE BITTEN BY IXODID TICKS ABROAD OF THE RUSSIAN FEDERATION

Introduction. Annually, there are several patients attended the Center for Diagnosis and Prevention of Tick-borne Infections in  Irkutsk after bites of ticks that happened outside the Pribaikalye  region or abroad. In such cases, the attacking ticks do not belong to  convenient species that are usual for Eastern Siberia. Consequently,  the spectrum of pathogenic microorganisms transmitted by these  ticks may significantly differ from those that are detected by usual  laboratory tests. Thus, both physicians and laboratory personnel may  have difficulties in proper detection and identification of pathogens as well as in diagnosing and treating of such patients.

The purpose of the study was the analysis of potential risks of human infection with the pathogens that are common in foreign countries outside the Russian Federation.

Material and methods. The article uses information from electronic databases created by the authors during 2007-2017.

Results and discussion. During 11 years of observations, 52 tick bites were registered in 20 countries, with 48 of them in the Eastern  Hemisphere (92.3 %), three (5.8 %) in the United States and one  (1.9 %) in the Republic of Cuba. The results indicate a real danger of infection by tick-borne pathogens of people traveling as the tourists  and with business purposes to the countries of Europe, Asia and America.

 

Conclusion. It is necessary to improve the existing algorithm for diagnosis, prevention and treatment for people bitten by ixodid ticks  outside the Russian Federation, taking into account the possibility of  infection by inconvenient imported infections.

Mobile populations across the Mediterranean Sea and beyond: travel medicine, mass gathering medicine and homeless health

The Méditerranée Infection institute is internationally recognized for its expertise in infectious diseases and tropical medicine, and is one of the most active research centres for infectious diseases in Europe. Surveillance and research addressing infectious diseases in globally mobile populations is one of the strong components of the research conducted at the institute. A significant amount of clinical, microbiologic and epidemiologic works have been conducted in international travellers, pilgrims participating in large international religious gatherings, economic migrants and homeless migrant people over the last decades by our group. Our strong anchoring in several countries around the Mediterranean Sea and beyond, as well as the pivotal role of Marseille in the EuroTravNet and GeoSentinel international networks that monitor travel-associated diseases, reinforce our leading position in the fields of travel and tropical medicine, mass gathering medicine and homeless health.

Seek and Find! PCR analyses of skin infections in West-European travelers returning from abroad with an eschar

BACKGROUND

Skin infections are among the leading causes of diseases in travelers. Diagnosing pathogens could be difficult.

METHOD

We applied molecular assays for the diagnostic of a large collection of skin biopsies and swabs from travelers with suspected skin infections. All samples were tested by qPCR for Coxiella burnetti, Bartonella sp., Rickettsia sp., Borrelia sp., Ehrlichia sp., Tropheryma whipplei, Francisella tularensis, Mycobacteria sp., Staphylococcus aureus, Streptococcus pyogenes, Leishmania spp., Ortho poxvirus and Para poxvirus and then screened for the presence of bacteria by PCR amplification and sequencing, targeting the 16S rRNA gene.

RESULTS

From January 2009 to January 2017, 100 international travelers presenting with a suspected skin infection were enrolled. We detected 51 patients with an identified pathogen on skin samples. Travelers presenting with eschars were more likely to have a positive PCR sample (n = 44/76, 57.9%) compared to other patients (n = 7/24, 29.2%). Spotted fever group Rickettsia (n = 28) was the most frequently detected pathogens (19 R. africae, 6 R. conorii, 3 R. mongolitimonae); S. aureus were detected in 11 patients; S. pyogenes in 3; Leishmania sp.; M. leprae and B. henselae in 1 patient, respectively.

CONCLUSION

By targeting the most commonly encountered causative agents of travel-related skin infections, our strategy provides a sensitive and rapid diagnostic method.

Infectious disease risk and international tourism demand

Context

 For some countries, favourable climatic conditions for tourism are often associated with favourable conditions for infectious diseases, with the ensuing development constraints on the tourist sectors of impoverished countries where tourism's economic contribution has a high potential. This paper evaluates the economic implications of eradication of Malaria, Dengue, Yellow Fever and Ebola on the affected destination countries focusing on the tourist expenditures.

Methods

 A gravity model for international tourism flows is used to provide an estimation of the impact of each travel-related disease on international tourist arrivals. Next the potential eradication of these diseases in the affected countries is simulated and the impact on tourism expenditures is estimated.

Findings

 The results show that, in the case of Malaria, Dengue, Yellow Fever and Ebola, the eradication of these diseases in the affected countries would result in an increase of around 10 million of tourist worldwide and a rise in the tourism expenditure of 12 billion dollars.

Conclusion

 By analysing the economic benefits of the eradication of Dengue, Ebola, Malaria, and Yellow Fever for the tourist sector-a strategic economic sector for many of the countries where these TRD are present-this paper explores a new aspect of the quantification of health policies which should be taken into consideration in future international health assessment programmes. It is important to note that the analysis is only made of the direct impact of the diseases' eradication and consequently the potential multiplicative effects of a growth in the GDP, in terms of tourism attractiveness, are not evaluated. Consequently, the economic results can be considered to be skeleton ones.

Redefining priorities towards graded travel-related infectious disease research

Our knowledge of the health problems and infections encountered by international travellers has evolved considerably in the past decades. The growth of global networks such as the GeoSentinel Surveillance network, TropNet Europe, EuroTravNet and networks based in North America have provided valuable information on the frequency of a wide array of travel-related diseases and accidents, including details on the destination of travel and trends over time. The information gained from these network studies has provided important data for the practice of travel medicine and in some instances for the development of practice guidelines. However, network data due to a lack of denominators usually cannot serve as a basis for a GRADE approach to guideline development. Although epidemiological network studies will continue to serve an important role in travel medicine we encourage an additional strong focus towards translational scientific research questions and towards the broader use of novel techniques to obtain more accurate epidemiological analyses to address the many unanswered questions in our field.

Non-falciparum malaria imported mainly from Africa: a review from a Portuguese hospital

BACKGROUND

Non-falciparum malaria (NFM) has been reported to be responsible for around 25% of imported malaria cases in Europe but is often neglected due to its less severe clinical course when compared to Plasmodium falciparum. Differentiation between species is however crucial for a correct approach. The objective of this study is to report the cases of this often missed aetiology of malaria in a tertiary hospital in Portugal.

METHODS

Data were retrospectively analysed from patients admitted from January 2006 to August 2016 with a NFM diagnosis based on microscopy, rapid diagnostic tests (RDT) (BinaxNow^®) and/or PCR. Epidemiologic and clinical aspects were reviewed.

RESULTS

A total of 19 NFM cases were diagnosed, corresponding to 8.4% of the total 225 cases of malaria. Seventeen (89%) were male with a median age of 41 years. All but one case were imported from sub-Saharan Africa, with 12 (63%) of the cases returned from Angola. Microscopy was positive for all patients and correctly identified the species in 12 (63%) patients. BinaxNOW^® was performed in all patients and it was positive in 11 cases, showing a sensitivity of 58%. PCR was performed in nine patients and was positive in eight of them, being responsible for the identification of the species in four cases. Plasmodium malariae accounted for 37% (n = 7) of the cases, Plasmodium ovale for 32% (n = 6) and Plasmodium vivax for 17% (n = 3). In three (16%) patients, morphology was suggestive of P. vivax or P. ovale, but precise species identification was not possible. Regarding presentation, fever was the most reported symptom, and the most frequent laboratory finding was thrombocytopaenia. Quinine-doxycycline was prescribed in eleven patients (58%), chloroquine in six cases (32%) and artemether-lumefantrine in two (11%). All of the patients showed clinical improvement.

CONCLUSIONS

NFM remains an important cause of imported malaria in patients from sub-Saharan Africa, alone or as mixed infection with P. falciparum. Access to PCR techniques facilitates diagnosis, as low sensitivity from RDTs and microscopy are to be expected.

Pre-travel advice at a crossroad: Medical preparedness of travellers to South and Southeast-Asia - The Hamburg Airport Survey

BACKGROUND

Specific travel-related recommendations exist for the prevention or self-treatment of infectious diseases contracted by travellers to the tropics. In the current study, we assessed the medical preparedness per these recommendations, focusing on whether travellers carried antidiarrheal and antimalarial medication with them stratified by type of pre-travel advice.

METHODS

We surveyed travellers departing from Hamburg International Airport to South or Southeast Asia, using a questionnaire on demographic, medical and travel characteristics.

RESULTS

975 travellers were analysed - the majority (817, 83%) being tourists. A large proportion packed any antidiarrheal medication (612, 63%) - most frequently loperamide (440, 72%). Only 176 of 928 (19%) travellers to destinations with low-to medium risk for malaria packed a recommended antimalarial medication. The majority (162, 17%) of them carried antimalarials as stand-by emergency treatment (SBET). 468 (48%) travellers had a pre-travel medical consultation. This lead to higher odds of carrying SBET- with the highest odds associated with a consultation at a travel medicine specialist (OR 7.83 compared to no consultation).

CONCLUSIONS

Attending a travel medicine specialist was associated with better adherence to current recommendations concerning the carriage of stand-by emergency treatment of malaria. However, the proportion of travellers seeking pre-travel health advice was overall low in our population. Promoting pre-travel consultations may, therefore, lead to higher adherence to the current recommendations in travel medicine.

Frequency of infectious diseases in immigrants in a Western European country: a population-based study

The aim of this population-based study was to assess the incidence rates of infectious diseases in native- (Italian) and foreign-born (immigrants) populations in a North Italy area, in 2006-2010. Crude, age-specific incidence rates (IRs) and age-standardised rate ratios (SRRs) between foreign- and native-born subjects and their 95% confidence intervals (95% CI) were estimated. A total of 32,554 cases of infectious diseases were found (9.9% in foreign-born subjects). The highest SRRs between foreign- and nativeborn subjects were found for tuberculosis (SRR = 27.1; 95% CI 21.3-34.3), malaria (SRR = 21.1; 14.6-30.4), scabies (SRR = 8.5; 7.6-9.4), AIDS (SRR = 2.5; 1.8-3.4) and viral hepatitis B (SRR = 3.3; 2.1-5.2). The highest IR was found for AIDS in people from the Americas (IR = 4.57; 95% CI 2.2-8.4), for malaria and tuberculosis in people from Africa (IR = 13.89; 11.6-16.5 and IR = 11.87; 9.8-14.3 respectively). Therefore immigrants are at a higher risk of acquiring some common infectious diseases compared to the native population in Western European countries.

Diseases affecting patients returning from abroad: Experience of a travel clinic in Japan from 2004 to 2014

The number of patients returning from or staying abroad is likely to increase in the future. We performed a retrospective study of patients returning from abroad in our travel clinic in Japan. All patients presenting within 6 months of traveling abroad between 2004 and 2014 were included in the present study. A total of 2374 (mean age, 35 years) patients were seen by doctors specializing in treating infectious diseases. Of these, 918 were females and 87 of them lived abroad. Diagnoses and exposure regions were recorded for all patients. The most frequent region visited before attending our clinic was Southeast Asia (n = 1050, 44%), with a median duration for staying abroad of 8 days. The major purposes for overseas travel were tourism (n = 1302, 55%) and business (n = 684, 29%). Of the 2399 individual diagnoses made, the most frequent were diseases of the gastrointestinal system (n = 1083, 45%), skin and soft tissue (n = 440, 18%), systemic febrile disease without specific systems (419, 18%), and the respiratory system (353, 15%). The relative incidences of specific diseases changed drastically due to significant disease outbreaks, such as pandemic influenza in 2009. Exposure regions remained relatively constant throughout the study period, except for Japan. Vaccine-preventable diseases accounted for 5.3% of all the diseases, and 402 (26%) patients received pre-travel consultation and prophylaxis with vaccines and/or anti-malarial drug. We should make an effort to make more people notice the risk of travel and properly perform prophylaxis.

A closer look at travellers' infections abroad: Finnish nationwide data with incidences, 2010 to 2012

BACKGROUND

Although infections represent the most common health problem of travellers abroad, data on morbidity and incidences of various infections are scarce.

METHOD

Data on infections of Finnish travellers during 2010-2012 were retrieved from the database of SOS International, an assistance organization covering 95% of Finns requiring aid abroad. The study included 30,086 cases. For incidence calculation, the data were linked to the numbers of Finns visiting these regions during the same period as recorded by the Official Statistics of Finland.

RESULTS

The incidence of infections was particularly high in Africa, southern Europe plus the eastern Mediterranean, and Asia plus Oceania. The most frequent diagnoses were acute gastroenteritis (38.0%) and respiratory-tract infections (RTI) (34.5%), followed by infections of the ear (12.6%), skin or subcutaneous tissue (5.1%), urogenital tract (4.2%), eye (3.1%), and systemic febrile infections (2.2%). Vaccine-preventable diseases (VPD) accounted for 0.8% of cases, with varicella as most (49%) and influenza as second-most (27%) common.

CONCLUSIONS

Incidence of infections was higher in southern than in eastern and western Europe. Gastroenteritis and RTI proved the most frequent diagnoses, whereas systemic febrile infections were uncommon. Despite pre-travel immunizations, VPDs still occurred; pre-travel consultation should cover both varicella and influenza.

Meningococcal vaccination for international travellers from Greece visiting developing countries

BACKGROUND

Meningococcal meningitis is a serious disease. Travel-associated infection for the general traveller is low; however regular epidemics in indigenous population, particularly in sub-Saharan Africa are responsible for significant morbidity and mortality. Our aim was to assess meningococcal vaccination for international travellers from Greece.

METHODS

A prospective questionnaire-based study was conducted during 2009-2013.

RESULTS

A total of 5283 travellers were studied (median age: 39.2 years); Meningococcal tetravalent vaccine (A,C,W135,Y) was delivered to 1150 (21.8%) of them. Of those who travelled to the Middle East and sub-Saharan Africa, 73.1% and 21.2% received meningococcal vaccine, respectively. Of those travellers who travelled to sub-Saharan Africa from November to June and from July to October, 22.1% and 20.6% were vaccinated with meningococcal vaccine, respectively. Of all travellers who travelled for <1 month and ≥1 month, 23.3%, and 20.5%, were vaccinated, respectively. Meningococcal vaccine was administered to 95.3% of pilgrims, 17.4% of those visiting friends and relatives (VFRs), 16.7% of those who travelled for recreation, and 13.8% of those who travelled for work. Of travellers who stayed in urban, in rural, and in urban and rural areas, 32%, 11.6% and 12.7% were vaccinated, respectively. Meningococcal vaccine was delivered to 29.2%, 21.1%, 19.4% and 5.1% of those who stayed in hotels, at local people's home, in camps, and on ships, respectively. The association of meningococcal vaccine administration with the destination, duration and purpose of travel, area of stay and type of accommodation was statistically significant.

CONCLUSION

There is a need to improve meningococcal vaccine recommendations for travellers from Greece, particularly for high risk populations, such as VFRs, business travellers and those visiting sub-Saharan Africa especially during the dry season.

Crimean-Congo haemorrhagic fever in travellers: A systematic review

Background

The recent Ebola epidemic has increased public awareness of the risk of travel associated viral haemorrhagic fever (VHF). International preparedness to manage imported cases Ebola virus infection was inadequate, highlighted by cases of nosocomial transmission. Crimean-Congo haemorrhagic fever (CCHF) is a re-emerging tick-borne VHF centred in the Eurasian region, affecting a large geographical area and with human-to-human transmission reported, especially in the healthcare setting.

Objectives

To systematically review the characteristics of travel associated Crimean-Congo haemorrhagic fever.

Methods

A systematic review of travel-associated cases of CCHF was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement protocol. PubMed, SCOPUS, Science Citation Index (SCI) and ProMED databases were searched for reports published between January 1960 and January 2016. Three independent reviewers selected and reviewed studies and extracted data.

Results

21 cases of travel associated CCHF were identified, of which 12 died (3 outcome unknown) and 4 secondary (nosocomial) infections were reported. Risk occupations or activities for CCHF infection were reported in 8/12 cases when data were available. Travel from Asia to Asia occurred in 9 cases, Africa to Africa occurred in 5 cases, Africa to Europe in 3 cases, Asia to Europe in 2 cases and Europe to Europe in 2 cases.

Conclusion

CCHF related to travel is rare, is generally associated with at risk activities/occupation and is frequently fatal. Key to early diagnosis and prevention of nosocomial transmission is an understanding of CCHF risk factors and the geographical distribution of CCHF. International travel to CCHF endemic areas is increasing and clinicians and laboratory personnel managing returning travellers should maintain a high index of suspicion.

Spectrum of Imported Infectious Diseases: A Comparative Prevalence Study of 16,817 German Travelers and 977 Immigrants from the Tropics and Subtropics

The aim of this study was to assess the spectrum of imported infectious diseases (IDs) among patients consulting the University of Munich, Germany, between 1999 and 2014 after being in the sub-/tropics. The analysis investigated complete data sets of 16,817 diseased German travelers (2,318 business travelers, 4,029 all-inclusive travelers, and 10,470 backpackers) returning from Latin America (3,225), Africa (4,865), or Asia (8,727), and 977 diseased immigrants, originating from the same regions (112, 654 and 211 respectively). The most frequent symptoms assessed were diarrhea (38%), fever (29%), and skin disorder (22%). The most frequent IDs detected were intestinal infections with species of Blastocystis(900),Giardia(730),Campylobacter(556),Shigella(209), and Salmonella(183). Also frequently observed were cutaneous larva migrans (379), dengue (257), and malaria (160). The number of IDs with significantly elevated proportions was higher among backpackers (18) and immigrants (17), especially among those from Africa (18) and Asia (17), whereas it was lower for business travelers (5), all-inclusive travelers (1), and those from Latin America (5). This study demonstrates a large spectrum of imported IDs among returning German travelers and immigrants, which varies greatly based not only on travel destination and origin of immigrants, but also on type of travel.

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

BACKGROUND

The travel clinic in Lausanne serves a catchment area of 700 000 of inhabitants and provides pre- and post-travel consultations. This study describes the profile of attendees before departure, their travel patterns and the travel clinic practices in terms of vaccination over time.

METHODS

We included all pre-travel first consultation data recorded between November 2002 and December 2012 by a custom-made program DIAMM/G. We analysed client profiles, travel characteristics and vaccinations prescribed over time.

RESULTS

Sixty-five thousand and forty-six client-trips were recorded. Fifty-one percent clients were female. Mean age was 32 years. In total, 0.1% were aged <1 year and 0.2% ≥80 years. Forty-six percent of travellers had pre-existing medical conditions. Forty-six percent were travelling to Africa, 35% to Asia, 20% to Latin America and 1% (each) to Oceania and Europe; 19% visited more than one country. India was the most common destination (9.6% of travellers) followed by Thailand (8.6%) and Kenya (6.4%). Seventy-three percent of travellers were planning to travel for ≤ 4 weeks. The main reasons for travel were tourism (75%) and visiting friends and relatives (18%). Sixteen percent were backpackers. Pre-travel advice were sought a median of 29 days before departure. Ninety-nine percent received vaccine(s). The most frequently administered vaccines were hepatitis A (53%), tetanus-diphtheria (46%), yellow fever (39%), poliomyelitis (38%) and typhoid fever (30%).

CONCLUSIONS

The profile of travel clinic attendees was younger than the general Swiss population. A significant proportion of travellers received vaccinations that are recommended in the routine national programme. These findings highlight the important role of travel clinics to (i) take care of an age group that has little contact with general practitioners and (ii) update vaccination status. The most commonly prescribed travel-related vaccines were for hepatitis A and yellow fever. The question remains to know whether clients do attend travel clinics because of compulsory vaccinations or because of real travel health concern or both.

Syndromic Approach to Arboviral Diagnostics for Global Travelers as a Basis for Infectious Disease Surveillance

BACKGROUND

Arboviruses have overlapping geographical distributions and can cause symptoms that coincide with more common infections. Therefore, arbovirus infections are often neglected by travel diagnostics. Here, we assessed the potential of syndrome-based approaches for diagnosis and surveillance of neglected arboviral diseases in returning travelers.

METHOD

To map the patients high at risk of missed clinical arboviral infections we compared the quantity of all arboviral diagnostic requests by physicians in the Netherlands, from 2009 through 2013, with a literature-based assessment of the travelers' likely exposure to an arbovirus.

RESULTS

2153 patients, with travel and clinical history were evaluated. The diagnostic assay for dengue virus (DENV) was the most commonly requested (86%). Of travelers returning from Southeast Asia with symptoms compatible with chikungunya virus (CHIKV), only 55% were tested. For travelers in Europe, arbovirus diagnostics were rarely requested. Over all, diagnostics for most arboviruses were requested only on severe clinical presentation.

CONCLUSION

Travel destination and syndrome were used inconsistently for triage of diagnostics, likely resulting in vast under-diagnosis of arboviral infections of public health significance. This study shows the need for more awareness among physicians and standardization of syndromic diagnostic algorithms.

Management of imported cutaneous larva migrans: A case series and mini-review

BACKGROUND

Cutaneous larva migrans (CLM), a zoonotic helminthiasis imported to Canada by travelers to the tropics, causes morbidity due to severe, intractable pruritus. Treatment in Canada is only available through the Special Access Program (SAP) of Health Canada, thus, many patients are prescribed ineffective courses of non-targeted therapy.

OBJECTIVE

We analyzed patients with CLM referred to our specialized Tropical Disease Unit (TDU) having failed non-targeted therapy prior to referral, and characterized demographic and travel related correlates of CLM.

METHODS

Patients with CLM evaluated between June 2012 and December 2014 were identified through our SAP application log, and charts were reviewed for demographic, clinical, and travel-related data following IRB approval.

RESULTS

25 patients with CLM were identified: 12 women, and 13 men. Median age was 35 years (range 4-58 years). Patients had primarily acquired their CLM in the Caribbean (80%), with Jamaica being the most well represented source destination (N = 10, 40%). Reported symptoms included intense, function-limiting pruritus (N = 25, 100%) and loss of sleep (N = 3, 12%). Twelve patients (48%) with CLM had received at least 1 course of non-targeted therapy prior to referral. Non-targeted therapies included topical steroids (N = 7), cryotherapy (N = 3), oral antibiotics (N = 2), and oral mebendazole (N = 11). Median duration of symptoms was 34 days (range 5-226 days). Of 25 patients with CLM, 23 (92%) were prescribed a single 3-day course of albendazole and responded appropriately, and 2 (8%) required a second 3-day course of albendazole.

CONCLUSIONS

Although CLM is non-communicable and of little public health relevance in Canada, it causes significant morbidity. A substantial proportion of patients with CLM referred to our specialized TDU had a prolonged course of illness and were prescribed ineffective and non-targeted therapies. Oral albendazole or ivermectin, or topical thiabendazole, are the drugs of choice for CLM, and should be prescribed as first-line therapy.

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

Binary file ES_Abstracts_Final_ECDC.txt matches

Conflict in Neighboring Countries, a Great Risk for Malaria Elimination in Southwestern Iran: Narrative Review Article

The intensity of the conflict such as war is one of the determinants of the flow of migrants and refuges with consequence of introducing infectious disease to other countries. This paper investigates the relationship between malaria incidence and forced immigration due to war from neighboring countries in Dezful district, southwestern Iran. All available data and accessible archived documentary records on malaria cases in the period 1988-2011 in Dezful Health Centers were reviewed. Retrospective analysis of routine surveillance data from the Health authority of Dezful district was conducted to assess the trend of malaria incidence and prevalence in the last two decades. Malaria transmission dynamics was described using surveillance indicators viz, Annual Parasite Incidence (API), Slide Positivity Rate (SPR), Annual Blood Examination Rate (ABER) and based on personal information of patients. Two peaks of malaria incidence occurred during past two decades. The first one arisen by Iran-Iraq war due to residential instability in Dezful while the API reached to 8 per 1000. The second peak happened after to civil war of Afghanistan began which caused large immigrates moved into the study area. During the second peak, API reached 1.7 per 1000 at maximum and the majority of patients were immigrants. This study describes the linkage between incidence and prevalence of malaria and immigration due to civil conflict. Therefore, malaria screening of immigrants and early warning programme are effective to prevent outbreak of disease in a potential risk area such Dezful.

Efficacy and safety of artemisinin combination therapy (ACT) for non-falciparum malaria: a systematic review

Background

Artemisinin combination therapy (ACT) is recommended as first-line treatment for uncomplicated Plasmodium falciparum malaria, whereas chloroquine is still commonly used for the treatment of non-falciparum species (Plasmodium vivax, Plasmodium ovale and Plasmodium malariae). A more simplified, more uniform treatment approach across all malaria species is worthwhile to be considered both in endemic areas and for malaria as an imported condition alike.

Methods

A PROSPERO-registered systematic review to determine the efficacy and safety of ACT for the treatment of non-falciparum malaria was conducted, following PRISMA guidelines. Without language restrictions, Medline/PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, LILACS, Biosis Previews and the African Index Medicus were searched for studies published up to November 2014.

Results

The literature search identified 986 reports; 40 publications were found eligible for inclusion, all of them on non-falciparum malaria in endemic areas. Most evidence was available for P. vivax (n = 35). Five clinical trials in total were identified evaluating ACT for P. ovale, P. malariae and Plasmodium knowlesi. Most ACT presentations have high efficacy against P. vivax parasites; artemisinin-based combinations have shorter parasite and fever clearance times compared to chloroquine. ACT is as effective as chloroquine in preventing recurrent parasitaemia before day 28. Artemisinin-based combinations with long half-lives show significantly fewer recurrent parasitaemia up to day 63. The limited evidence available supports both the use of chloroquine and an ACT for P. ovale and P. malariae. ACT seems to be preferable for optimal treatment of P. knowlesi.

Conclusion

ACT is at least equivalent to chloroquine in effectively treating non-falciparum malaria. These findings may facilitate development of simplified protocols for treating all forms of malaria with ACT, including returning travellers. Obtaining comprehensive efficacy and safety data on ACT use for non-falciparum species particularly for P. ovale, P. malariae and P. knowlesi should be a research priority.

Trial registration

CRD42014009103

Electronic supplementary material

The online version of this article (doi:10.1186/1475-2875-13-463) contains supplementary material, which is available to authorized users.

Fever in the returning child traveller: approach to diagnosis and management

During the last half century there has been an exponential increase in international travel including to more exotic and long-haul destinations. The assessment of febrile returning child travellers presents diagnostic challenges and is often performed poorly. A detailed travel and medical history, clinical examination and appropriate first-line investigations are essential. While the majority of children will have a common self-limiting or easily treatable infection, it is important to consider other causes, including imported infections, which may be life-threatening or highly contagious. In this article, we provide guidance on the initial assessment and management of such children with a focus on some of the more important imported infections, including malaria, dengue, typhoid fever, travellers' diarrhoea, respiratory infections, tuberculosis, schistosomiasis and rickettsial diseases.

A profile of travelers--an analysis from a large swiss travel clinic

BACKGROUND

Globally, the Swiss have one of the highest proportions of the population traveling to tropical and subtropical countries. Large travel clinics serve an increasing number of customers with specific pre-travel needs including uncommon destinations and preexisting medical conditions. This study aims to identify health characteristics and travel patterns of travelers seeking advice in the largest Swiss travel clinic so that tailored advice can be delivered.

METHODS

A descriptive analysis was performed on pre-travel visits between July 2010 and August 2012 at the Travel Clinic of the Institute of Social and Preventive Medicine, University of Zurich, Switzerland.

RESULTS

A total of 22,584 travelers sought pre-travel advice. Tourism was the main reason for travel (17,875, 81.5%), followed by visiting friends and relatives (VFRs; 1,715, 7.8%), traveling for business (1,223, 5.6%), and "other reasons" (ie, volunteer work, pilgrimage, study abroad, and emigration; 1,112, 5.1%). The main travel destination was Thailand. In the VFR group, the highest proportions of traveling children (258, 15.1%) and of pregnant or breastfeeding women (23, 3.9%) were observed. Mental disorders were more prominent in VFRs (93, 5.4%) and in travel for "other reasons" (63, 5.7%). The latter stayed for the longest periods abroad; 272 (24.9%) stayed longer than 6 months. VFR travelers received the highest percentage of yellow fever vaccinations (523, 30.5%); in contrast, rabies (269, 24.2%) and typhoid vaccinations (279, 25.1%) were given more often to the "other travel reasons" group.

CONCLUSIONS

New insights into the characteristics of a selected and large population of Swiss international travelers results in improved understanding of the special needs of an increasingly diverse population and, thus, in targeted preventive advice and interventions.

Vaccination and malaria prophylaxis among Greek international travelers to Asian destinations

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Awareness of meningococcal disease among travelers from the United Kingdom to the meningitis belt in Africa

Meningococcal disease causes considerable morbidity and has a high case-fatality rate. In the United Kingdom, the meningococcal quadrivalent vaccine is recommended for travelers visiting the meningitis belt of Africa. We analyzed 302 responses to a cross-sectional study conducted in 2010 of travelers who had visited the meningitis belt recently or were shortly due to travel there. Using the results of an online questionnaire, we assessed knowledge and understanding of meningococcal disease and likelihood of uptake of meningococcal immunization before travel. Meningococcal vaccine uptake was 30.1%. Although global scores in the questionnaire did not correlate with vaccine uptake, knowledge of the meningitis belt and knowledge of certain key symptoms or signs were statistically associated with high vaccine uptake. We conclude that improved education of travelers may improve vaccine uptake before travel to the meningitis belt in Africa.

Morbidity and outcomes of foreign travelers in Zakynthos island, Greece: a retrospective study

Background

Although there is satisfactory recording of diseases affecting travelers visiting developing countries, little is known regarding morbidity of travelers when visiting developed countries. We sought to evaluate the morbidity of foreign travelers in Zakynthos, a popular Greek island attracting large number of foreign tourists every summer.

Methods

Data from foreign travelers that accommodated in Zakynthos and sought medical services from the private offices of Zante Medical Care from May 1 to October 30 2012 were retrospectively analyzed.

Results

Two thousand six hundred and eighty-eight patients were included in the study. The mean age (±SD) of the patients whom the age was recorded was 29.6 (±18.3) and 51.5% of them were from 18 to 40 years old. Disorders of the respiratory tract (32.7%), dermatologic conditions (21.1%), musculoskeletal injuries (16.4%), and gastrointestinal disorders (16.3%) were the four most prevalent clinical categories among patients. Ear disorder was the most common syndromic description (14.5%) among which 81.2% were ear infections; otitis externa and otitis media were diagnosed in 8.5% and 3.3% patients in total. The most common specific diagnosis was gastroenteritis (14.3%). Insect bite and sunburn were the most common diagnosis (6.5% and 3.8%, respectively) among patients with a dermatologic condition. Ear infection was the most common diagnosis in pediatric patients.

Conclusion

Disorders mainly of the upper respiratory tract were the predominant causes of illness among foreign travelers in Zakynthos. Traveler's diarrhea was the most common specific diagnosis but the prevalence within the total population was not very high.

Vaccination and Malaria Prevention among International Travelers Departing from Athens International Airport to African Destinations

Background. International travel to Africa has grown dramatically over the last decade along with an increasing need to understand the health issues for travelers. The current survey aimed to assess vaccination and malaria prevention of travelers visiting Africa. Methods. A questionnaire-based survey was conducted from of November 1, 2011 to of April 30, 2013 at Athens International Airport. Results. A total of 360 travelers were studied; 68% were men. Their mean age was 39.9 years. Previous travel to tropical countries was reported by 71.9% of them. Most frequent destination was sub-Saharan Africa (60%). Most of them traveled for ≥1 month (62%). The main reason for travel was work (39.7%). Only 47% sought pretravel consultation. Hepatitis A, typhoid, and meningococcal vaccines were administered to 49.8%, 28%, and 26.6%, respectively, and malaria chemoprophylaxis to 66.8% of those who visited sub-Saharan Africa. A history of previous travel to a tropical country, elementary level of education, and traveling for visiting friends and relatives, and for short duration were significant determinants for not pursuing pretravel consultation. Conclusions. The current survey revealed important inadequacies in vaccine and malaria prophylaxis of travelers departing to Africa. Educational tools should be developed in order to improve awareness of travelers to risk destinations.

Effect of travel on influenza epidemiology

To assess the attack and incidence rates for influenza virus infections, during October 2006–October 2007 we prospectively studied 1,190 adult short-term travelers from the Netherlands to tropical and subtropical countries. Participants donated blood samples before and after travel and kept a travel diary. The samples were serologically tested for the epidemic strains during the study period. The attack rate for all infections was 7% (86 travelers) and for influenza-like illness (ILI), 0.8%. The incidence rate for all infections was 8.9 per 100 person-months and for ILI, 0.9%. Risk factors for infection were birth in a non-Western country, age 55–64 years, and ILI. In 15 travelers with fever or ILI, influenza virus infection was serologically confirmed; 7 of these travelers were considered contagious or incubating the infection while traveling home. Given the large number of travelers to (sub)tropical countries, travel-related infection most likely contributes to importation and further influenza spread worldwide.