Blood and body fluid exposure as a health risk for international travelers

Clinicoepidemiological characteristics of viral hepatitis in migrants and travellers of the +Redivi network

BACKGROUND

Continuous growth of mobile populations has influenced the global epidemiology of infectious diseases, including chronic and acute viral hepatitis.

METHOD

A prospective observational multicentre study was performed in a Spanish network of imported infections. Viral hepatitis cases from January 2009 to September 2017 were included.

RESULTS

Of 14,546 records, 723 (4.97%) had imported viral hepatitis, including 48 (6.64%) acute cases and 675 (93.36%) chronic cases. Of the 48 acute cases, 31 were travellers and immigrants returning from visiting friends or relatives (VFR), while 19 (61%) were acute Hepatitis A or Hepatitis B. Only 18.2% of VFR immigrants and 35% of travellers received pre-travel advice. Acute hepatitis was more frequent in VFR immigrants (AOR 2.59, CI95% 1.20-5.60) and travellers (AOR 2.83, CI95% 1.46-5.50) than immigrants. Of the 675 Chronic cases, 570 were immigrants, and 439 (77%) had chronic Hepatitis B. Chronic hepatitis was more frequent in immigrants (AOR 20.22, CI95% 11.64-35.13) and VFR immigrants (AOR 11.12, CI95% 6.20-19.94) than travellers.

CONCLUSIONS

Chronic viral hepatitis was typical of immigrants, acute viral hepatitis was common among travellers, and VFR immigrants had mixed risk. Improving pre-travel consultation and screening of immigrants may contribute to preventing new cases of viral hepatitis and avoiding community transmission.

Pre-Travel Medical Preparation of Business and Occupational Travelers: An Analysis of the Global TravEpiNet Consortium, 2009 to 2012

The aim of the study was to understand more about pre-travel preparations and itineraries of business and occupational travelers.

Experiences of and attitudes towards HIV/STI prevention among holidaymaking men who have sex with men living in Sweden: a cross-sectional Internet survey

AIM

Foreign travellers and men who have sex with men (MSM) are prioritised groups for human immunodeficiency virus/sexually transmitted infection (HIV/STI) prevention efforts in Sweden because of high prevalence of sexual risk-taking. This study aims to describe experiences of and attitudes towards HIV/STI prevention efforts, prior to travelling abroad, among MSM, and to investigate the kinds of prevention efforts that are desirable.

METHODS

The study is based on survey responses from 656 MSM who had travelled abroad. Recruitment took place through a Nordic website, and had a cross-sectional design. The analysis has mainly been descriptive, but bivariate analyses were performed using the chi-square test. The level of significance was p <.05.

RESULTS

Only a few of the participants had encountered HIV/STI prevention efforts in Sweden (5%) and abroad (23%), and a majority (58%) felt that it should be more prevalent. Having free access to condoms and lubricants was preferred among 68% of the men. Furthermore, having written information, as opposed to oral, was also preferred (68% vs. 26%). MSM felt that it was easy to find out information (79%) and claimed they would use the Internet to do so (87%).

CONCLUSIONS

Service providers who offer their services to travellers are encouraged to provide helpful links to information about sexual health. Information that is geared towards risk groups such as young adults should be presented with awareness that MSM are also part of that group. It is important for information to be conveyed respectfully to everyone, but perhaps MSM in particular, since they may have experienced feelings of being stigmatised or discriminated against previously.

International travel patterns and travel risks for stem cell transplant recipients

BACKGROUND

Stem cell transplantation (SCT) is being increasingly utilized for multiple medical illnesses. However, there is limited knowledge about international travel patterns and travel-related illnesses of stem cell transplant recipients (SCTRs).

METHODS

An observational cross-sectional study was conducted among 979 SCTRs at Memorial Sloan Kettering Cancer Center using a previously standardized and validated questionnaire. International travel post SCT, pre-travel health advice, exposure risks, and travel-related illnesses were queried.

RESULTS

A total of 516 SCTRs completed the survey (55% response rate); of these, 40% were allogeneic SCTRs. A total of 229 (44.3%) respondents reported international travel outside the United States and Canada post SCT. The international travel incidence was 32% [95% confidence interval CI 28-36] within 2 years after SCT. Using multivariable Cox regression analysis, variables significantly associated with international travel within first 2 years after SCT were history of international travel prior to SCT [hazard ratio (HR) = 5.3, 95% CI 2.3-12.0], autologous SCT (HR = 2.6, 95% CI 1.6-2.8), foreign birth (HR = 2.3, 95% CI 1.5-3.3), and high income (HR = 2.0, 95% CI 1.8-3.7). During their first trip, 64 travelers (28%) had traveled to destinations that may have required vaccination or malaria chemoprophylaxis. Only 56% reported seeking pre-travel health advice. Of those who traveled, 16 travelers (7%) became ill enough to require medical attention during their first trip after SCT. Ill travelers were more likely to have visited high-risk areas (60 vs 26%, p = 0.005), to have had a longer mean trip duration (24 vs 12 days, p = 0.0002), and to have visited friends and relatives (69 vs 21%, p < 0.0001).

CONCLUSIONS

International travel was common among SCTRs within 2 years after SCT and was mainly to low-risk destinations. Although the overall incidence of travel-related illnesses was low, certain subgroups of travelers were at a significantly higher risk. Pre-travel health counseling and interventions were suboptimal.

Travel-acquired infections in Canada: CanTravNet 2011-2012

BACKGROUND

Important gaps remain in our knowledge of the infectious diseases people acquire while travelling and the impact of pathogens imported by Canadian travellers.

OBJECTIVE

To provide a surveillance update of illness in a cohort of returned Canadian travellers and new immigrants.

METHODS

Data on returning Canadian travellers and new immigrants presenting to a CanTravNet site between September 2011 and September 2012 were extracted and analyzed by destination, presenting symptoms, common and emerging infectious diseases and disease severity.

RESULTS

During the study period, 2283 travellers and immigrants presented to a CanTravNet site, 88% (N=2004) of whom were assigned a travel-related diagnosis. Top three destinations for non-immigrant travellers were India (N=132), Mexico (N=103) and Cuba (N=89). Fifty-one cases of malaria were imported by ill returned travellers during the study period, 60% (N=30) of which were Plasmodium falciparum infections. Individuals travelling to visit friends and relatives accounted for 83% of enteric fever cases (15/18) and 41% of malaria cases (21/51). The requirement for inpatient management was over-represented among those with malaria compared to those without malaria (25% versus 2.8%; p<0.0001) and those travelling to visit friends and relatives versus those travelling for other reasons (12.1% versus 2.4%; p<0.0001). Nine new cases of HIV were diagnosed among the cohort, as well as one case of acute hepatitis B. Emerging infections among travellers included hepatitis E virus (N=6), chikungunya fever (N=4) and cutaneous leishmaniasis (N=16). Common chief complaints included gastrointestinal (N=804), dermatologic (N=440) and fever (N=287). Common specific causes of chief complaint of fever in the cohort were malaria (N=47/51 total cases), dengue fever (14/18 total cases), enteric fever (14/17 total cases) and influenza and influenza-like illness (15/21 total cases). Animal bites were the tenth most common diagnosis among tourist travellers.

INTERPRETATION

Our analysis of surveillance data on ill returned Canadian travellers provides a recent update to the spectrum of imported illness among travelling Canadians. Preventable travel-acquired illnesses and injuries in the cohort include malaria, enteric fever, HIV, hepatitis B, hepatitis A, influenza and animal bites. Strategies to improve uptake of preventive interventions such as malaria chemoprophylaxis, immunizations and arthropod/animal avoidance may be warranted.

Perceptions of HIV/STI prevention among young adults in Sweden who travel abroad: a qualitative study with focus group and individual interviews

BACKGROUND

Young adults are at risk for HIV/STIs because they generally have an active sex life with multiple sexual partners; moreover, they use condoms to a lesser extent. Travelling increases sexually risky behaviour, and among both women and men, sexual contacts abroad are common. Better knowledge of how young adults experience prevention efforts prior to travelling, and what they prefer, is important when planning prevention efforts to this group. Experiences of and attitudes towards prevention efforts against HIV/STI among young adults in Sweden who have travelled abroad were investigated.

METHOD

We conducted 12 focus-group interviews and four individual interviews with young adults (20-29 years) who had travelled abroad within the last 12 months. The interviews were recorded, transcribed verbatim, and analysed using thematic content analysis. Results were discussed from a salutogenic perspective.

RESULTS

Only a few had any experience of prevention efforts against HIV/STIs. The majority welcomed the idea of prevention efforts prior to travelling and would have welcomed more, preferably short reminders or links to reliable websites, or someone professional to discuss the issue with. Most of the young adults would use the Internet to search for information. They proposed the possibility of reaching young adults through social media, and the importance of better basic knowledge in school.

CONCLUSION

It is difficult to reach young adults before their trips abroad. Prevention efforts on HIV/STI must therefore focus on the use of established forums. Setting the foundation for a positive attitude towards condom use is needed during school years. Even social media, where there is the possibility for dialogue, should be used as an information source.

Travel medicine research priorities: establishing an evidence base

BACKGROUND

Travel medicine is the medical subspecialty which promotes healthy and safe travel. Numerous studies have been published that provide evidence for the practice of travel medicine, but gaps exist.

METHODS

The Research Committee of the International Society of Travel Medicine (ISTM) established a Writing Group which reviewed the existing evidence base and identified an initial list of research priorities through an interactive process that included e-mails, phone calls, and smaller meetings. The list was presented to a broader group of travel medicine experts, then was presented and discussed at the Annual ISTM Meeting, and further revised by the Writing Group. Each research question was then subject to literature search to ensure that adequate research had not already been conducted.

RESULTS

Twenty-five research priorities were identified and categorized as intended to inform pre-travel encounters, safety during travel, and post-travel management.

CONCLUSION

We have described the research priorities that will help to expand the evidence base in travel medicine. This discussion of research priorities serves to highlight the commitment that the ISTM has in promoting quality travel-related research.

Fever in returned travellers presenting in the United Kingdom: recommendations for investigation and initial management

International travel is increasing. Most physicians and general practitioners will encounter returned travellers with fever and the majority of travel-related infection is associated with travel to the tropics. In those returning from the tropics malaria must always be excluded, and HIV considered, from all settings. Common causes of non-malarial fever include from Africa rickettsial diseases, amoebic liver abscess and Katayama syndrome; from South and South East Asia, enteric fever and arboviral infection; from the Middle East, brucellosis and from the Horn of Africa visceral leishmaniasis. Other rare but important diseases from particular geographical areas include leptospirosis, trypanosomiasis and viral haemorrhagic fever. North and South America, Europe and Australia also have infections which are geographically concentrated. Empirical treatment may have to be started based on epidemiological probability of infection whilst waiting for results to return. The evidence base for much of the management of tropical infections is limited. These recommendations provide a pragmatic approach to the initial diagnosis and management of fever in returned travellers, based on evidence where it is available and on consensus of expert opinion where it is not. With early diagnosis and treatment the majority of patients with a potentially fatal infection related to travel will make a rapid and full recovery.

The role of the traveler in emerging infections and magnitude of travel

Travel and trade have grown immensely. Travelers interact with people and microbes during their journeys, and can introduce infectious agents to new areas and populations. Studying illnesses in travelers is a source of knowledge into diseases of resource-poor regions and the control of these diseases. Travel-associated illnesses also serve to detect emerging infections.

International travel and exposure risks in solid-organ transplant recipients

BACKGROUND

Although solid-organ transplant recipients (SOTR) have an increased risk of acquiring illnesses, they may not receive optimal pretravel care. We conducted a cross-sectional survey of travel activities and outcomes among SOTR.

METHODS

Two thousand five hundred fifty-four consecutive living SOTR from Mayo Clinic were surveyed regarding travel practices, pretravel counseling, exposure risks, and illness using a previously standardized and validated questionnaire.

RESULTS

One thousand one hundred thirty SOTR (44%) responded to the survey and were included in the study. The most common transplanted organs were liver (519 patients) and kidney (515 patients). Three hundred and three (27%) respondents reported travel outside of the United States or Canada after their transplant. Liver recipients were more likely to travel than other organ recipients. Ninety-six percent of travelers reported that they did not seek specific pretravel healthcare before their trip. Forty-nine SOTR (16%) traveled to destinations at higher risk for infectious diseases; travelers to these destinations were more likely to be men (73% vs. 54% of low-infection risk travelers, P=0.018) or born outside the United Stated or Canada (29% vs. 6% P<0.0001). Twenty-four travelers (8%) required medical attention because of illness; illness was more likely among travelers to high-infection risk (18%) than low-risk (6%) destinations, P=0.004.

CONCLUSIONS

International travel was common after solid organ transplantation, although the majority traveled to destinations at low risk for infectious disease. Although generally SOTR were able to travel safely, travelers to destinations at high-risk for infection had a significant rate of illness. Pretravel counseling and interventions were infrequent and should be improved.

The underestimated risk of hepatitis A and hepatitis B: benefits of an accelerated vaccination schedule

Hepatitis A virus (HAV) and hepatitis B virus (HBV) are vaccine-preventable. Current recommendations advocate vaccination of non-immune adults at risk of exposure, including travelers to HAV or HBV endemic areas, individuals with high risk of contracting a sexually transmitted infection, and some correctional facility inmates. We review the use of an accelerated schedule to administer the combination hepatitis A and hepatitis B vaccine (Twinrix). Administering three doses over three weeks and a fourth at 12 months provides rapid initial protection of most individuals for whom the standard 6-month vaccination schedule would not be suitable, including last-minute travelers and short-term correctional facility inmates. Furthermore, we consider the role of a universal vaccination strategy in preventing the spread of HAV and HBV.

[The HIV-infected traveler: infectious risks and prevention]

Patients with human immunodeficient virus (HIV) must make special preparations before traveling. They have a higher risk of infection than the general population. They are more likely to develop malaria and the clinical episodes will be more severe, particularly in pregnant women. Prescriptions for malaria prophylaxis and treatment must take into account their interactions with antiretroviral drugs. Vaccination decisions require consideration of the risk and severity of the vaccine preventable diseases in the destination area, the nature of the vaccine, the patient's immune status, and the risk of virological rebound as a consequence of vaccination. Some countries have entry restriction for travelers with HIV. Special precautions may be necessary for transporting and storing antiretroviral medications.

Rapid and sustained immune response against hepatitis A and B achieved with combined vaccine using an accelerated administration schedule

BACKGROUND

Combined hepatitis A and B vaccine administered on an accelerated schedule provides a rapid immune response against both hepatitis A and B viruses, which might be especially relevant for individuals who need protection quickly.

METHODS

A prospective, open-label, randomized study to compare the immunogenicity and reactogenicity of the combined hepatitis A and B vaccine Twinrix (GlaxoSmithKline Biologicals, Rixensart, Belgium) (>or=720 EL.U/mL inactivated hepatitis A antigen and 20 microg/mL recombinant hepatitis B surface antigen [HBsAg]) administered at 0, 7, 21 to 30 days, and 12 months compared with concurrent administration of Havrix [GlaxoSmithKline Biologicals, Rixensart, Belgium (>or=1440 EL.U/mL inactivated hepatitis A antigen)] at 0 and 12 months, and Engerix-B [GlaxoSmithKline Biologicals, Rixensart, Belgium (20 microg/mL recombinant HBsAg)] at 0, 1, 2, and 12 months in seronegative healthy adults.

RESULTS

At month 13, the anti-hepatitis B seroprotection rates (>10 mIU/mL) for the combined vaccine compared to the monovalent hepatitis B vaccine were 96.4% (95% CI: 92.7-98.5) and 93.4% (95% CI: 89.0-96.4), respectively. The anti-hepatitis A seroconversion rates were 100% in both groups (95% CI: 98.1-100). At day 37, the anti-hepatitis A seroconversion rates were similar in both groups (98.5% for combined vaccine, 98.6% for the monovalent vaccine group), but the combined vaccine resulted in a statistically significantly ( p < 0.001) better anti-hepatitis B seroprotection compared to monovalent hepatitis B vaccine, 63.2% versus 43.5%, respectively. The reactogenicity profile was similar in both study groups.

CONCLUSIONS

The combined hepatitis A and B vaccine administered on an accelerated schedule was at least as immunogenic and as well tolerated as the corresponding monovalent vaccines.

Special infectious disease risks of expatriates and long-term travelers in tropical countries. Part II: infections other than malaria

A wide range of viral, bacterial, and protozoal diseases pose risk to long-term tropical travelers. Risk varies geographically and with lifestyle. For some infections, risk increases with duration of stay, coming to resemble that of the local population. Risk management strategies include vaccination, chemoprophylaxis, avoidance measures, and screening, where appropriate. Vaccination against hepatitis A and B, typhoid, and rabies is recommended for all long-term travelers to (sub-)tropical areas. Lowering of the vaccination threshold for Japanese encephalitis is suggested. Meningococcal disease is rare in travelers, but vaccination is safe and acceptable. The efficacy of Bacillus Calmette-Guérin (BCG) is uncertain; immunological testing avoids BCG's confounding of tuberculin testing. Diarrhea is common, and self-treatment may be recommended. Sexually transmitted infections including human immunodeficiency virus (HIV) are serious risks; education, screening, and HIV postexposure prophylaxis following involuntary exposure are recommended. Many infections are chronic or asymptomatic, and appropriate screening is recommended on return or after prolonged exposure.

Travel and sexually transmitted infections

Increasing population mobility and increasing frequency and variety of sexually transmitted infections (STI) are closely linked around the globe. Although all mobile populations are at increased risk for acquiring STIs, international travelers are the focus of this review. Several aspects of travel such as opportunity, isolation, and the desire for unique experiences all enhance the likelihood of casual sexual experiences while abroad. The situational loss of inhibition of travel can be markedly enhanced by alcohol and drugs. Several of the most important elements of the complex interaction between travel and STIs are discussed.

Travel medicine interventions and neurological disease

As a consequence of increased mobility worldwide, persons with underlying medical conditions set out on a journey more often than in the past. Among pre-existing medical conditions, some neurological diseases, including multiple sclerosis and other demyelinating diseases, Guillain-Barré syndrome and myasthenia gravis often create management problems to travel medicine practitioners. There is some concern that these conditions could be worsened either by naturally acquired infections or by some travel medicine interventions. The aim of this review is to suggest a practical approach to each of these conditions and to examine the feasibility and the impact of travel medicine interventions on the underlying disease.

Travel-related hepatitis B: risk factors and prevention using an accelerated vaccination schedule

Rates of global travel and tourism are increasing dramatically, especially to regions with medium or high endemicity for hepatitis A and B, such as Asia, Africa, Latin America, and the Middle East. International travelers to these areas should be protected against both hepatitis A and B, regardless of their anticipated length of stay. However, many travelers depart within weeks of planning their trip (too late to complete the accelerated 0-, 1-, 2-month regimen for hepatitis B), and a majority of those traveling depart without being vaccinated. Although extended-stay travelers are at high risk for hepatitis B, short-stay travelers also are at risk. The most commonly encountered risk factors for travel-related hepatitis B are casual sexual activity with a new partner, medical and dental care abroad, and in the expatriate community, adoption of children who are hepatitis B carriers. Although efficacy studies of accelerated schedules for hepatitis B immunization have not been conducted, the results of immunogenicity studies in healthy volunteers who received an accelerated, 3-dose regimen on a 0-,7-, and 21-day schedule suggest that excellent, rapid, and long-term protection will be conferred. More data are needed to assess the efficacy of accelerated schedules in persons aged >40 years and to determine whether a fourth dose of hepatitis B vaccine is needed in all age groups.

Travel patterns and risk behaviour of HIV-positive people travelling internationally

BACKGROUND

International travel is associated with an increased risk of enteric, vector-borne, sexually transmitted and blood-borne infections. These risks are even higher among immunocompromised people, such as those with HIV infection. We conducted a study to determine HIV-positive people's travel patterns and risk behaviours while abroad.

METHODS

We conducted an anonymous survey of HIV-positive people attending an HIV clinic in a tertiary care hospital in Toronto about their travel activities and pretravel precautions as well as their burden of illness and risk exposure during travel. We compared the characteristics of respondents who had travelled outside Canada and the United States (international travellers) with those of respondents who had not travelled internationally.

RESULTS

Of 290 HIV-positive people who participated in the study, 133 (45.9%) indicated that they had travelled internationally in the 5 years before the survey. These people were predominantly men (93.2%) and well educated (60.0% had a university level education), and they had travelled mostly for personal reasons (89.5%) on trips that lasted 3.6 weeks on average. Only 58 (43.6%) sought health advice before travelling, and only 17 (12.8%) sought advice from a travel clinic. Five (3.8%) had received live vaccines before travel, and 9 (6.8%) had taken malaria chemoprophylaxis. Of the 119 international travellers who were taking antiretroviral therapy; 35 (29.4%) reported either discontinuing their medications or being poorly compliant with the therapy while travelling. Thirty-one (23.3%) of the 133 international travellers reported having had casual sexual activity with new partners while travelling, and only 18 (58.1%) of them reported always using a condom. Twenty-one (15.8%) of the 133 reported having had risky exposure to sharps. Twenty-four (18.0%) said they had become ill enough while travelling to require medical attention.

INTERPRETATION

Only one-fifth of HIV-positive people surveyed who travelled internationally sought advice from a health professional before their trip. Their travel was associated with poor adherence to antiretroviral therapy, risky sexual practices and risky exposure to sharps.

Travel patterns and risk behavior in solid organ transplant recipients

BACKGROUND

International travel is associated with an increased risk of enteric, vector-borne and bloodborne infections. The risk of acquiring travel-related illness is higher in those who are immunocompromised. However, little is known about travel practices and risk behaviors in transplant recipients who travel. We herein profile transplant recipients who travel, and characterize their pre-travel precautions, travel activities, burden of illness, and exposure history.

METHODS

With the use of a standardized and validated questionnaire, patients attending a transplant clinic were surveyed regarding recent travel and risk behaviors.

RESULTS

Of 267 transplant recipients who participated, 95 (36%) indicated that they had recently traveled outside Canada and the USA. Their mean age was 49.9 years, 54% were male, and 54% were born outside Canada. Eighty-six percent of travelers were receiving at least two immunosuppressive drugs at the time of their trip. Sixty-six percent of travelers sought pre-travel advice, primarily from their transplant physician. Sixty-three percent traveled to areas where hepatitis A is endemic, but only 5% had received hepatitis A immunization. Fifty percent traveled to dengue- and malaria-endemic areas, but,25% adhered to mosquito prevention measures. Ten percent reported behaviors that exposed them to blood or body fluids, including injections, body piercing, and casual sexual activity.

CONCLUSIONS

Solid organ transplant recipients represent a unique group of compromised travelers; however, few were adequately protected against travel-associated enteric, vector-borne and bloodborne pathogens.

Travel epidemiology--a global perspective

In order to have a rational approach to necessary preventive measures it is essential to know the health risks. The 80 million travellers each year with destinations in Africa, Asia, Latin America, Pacific Islands and remote areas in Eastern Europe are exposed to a broad range of pathogens that are rarely encountered at home. The risk depends on the degree of endemicity in the area visited, the duration of stay, the individual behaviour and the preventive measures taken. Travellers' diarrhoea (TD) is the most frequent ailment of visitors to countries with poor hygiene. The incidence rate is 25-90% in the first 2 weeks abroad. The risk of TD is far less in travellers originating in a high risk country, as some immunity develops. Malaria is an important risk for travellers going to endemic areas. Without chemoprophylaxis, the monthly incidence is high in some destinations, among them frequently visited tropical Africa where 80-95% of the infections are due to Plasmodium falciparum. The incidence rates are lower in most endemic areas of Asia and Latin America where Plasmodium vivax predominates. The risk is nil in all capital cities of South America and SE Asia, as well as in many frequently visited tourist destinations. The diseases preventable by immunization will be discussed in a separate paper (Vaccination priorities; page 175). Sexually transmitted diseases occur frequently, as some travellers (5% of Europeans) engage in casual sex, approximately half of them without being protected by a condom. The prevalence for HIV-infection, syphilis, gonorrhoea, etc. often exceeds 50% in prostitutes. In some European countries, a major proportion of heterosexuals with newly acquired HIV-infection have acquired it while abroad.

Vaccination priorities

Selection of immunizations should be based on requirements and on risk of infection. According to the International Health Regulations, many countries require yellow fever vaccination and proof thereof as the International Certificate of vaccination. Additionally selected countries require proof of vaccination against cholera and meningococcal disease. A consultation for travel health advice is always an opportunity to ascertain that routine immunizations have been performed. Recommended immunizations often are more important for traveller's health than the required or routine ones. The most frequent vaccine preventable infection in non-immune travellers to developing countries is hepatitis A with an average incidence rate of 0.3% per month; in high risk backpackers or foreign-aid-volunteers this rate is 2.0%. Many immunizations are recommended for special risk groups only: there is a growing tendency in many countries to immunize all young travellers to developing countries against hepatitis B, as it is uncertain who will voluntarily or involuntarily get exposed. The attack rate of influenza in intercontinental travel is estimated to be 1%. Immunity against poliomyelitis remains essential for travel to Africa and parts of Asia. Many of the 0.2-0.4% who experience an animal bite are at risk of rabies. Typhoid fever is diagnosed with an incidence rate of 0.03% per month among travellers to the Indian subcontinent, North and West Africa (except Tunisia), and Peru, elsewhere this rate is 10-fold lower. Meningococcal disease, Japanese encephalitis, cholera and tuberculosis have been reported in travellers, but these infections are rare in this population. Although no travel health vaccine is cost beneficial, most professionals will offer protection against the frequent risks, while most would find it ridiculous to use all available vaccines in every traveller. It is essentially an arbitrary decision made on the risk level one wishes to recommend protection--but the priorities need to be set correctly.

Recent Advances and New Challenges in Travel Medicine

Recent advances in travel medicine include the use of computer resources to obtain information on outbreaks and recommendations to travelers, the introduction of atovaquone/proguanil as chemoprophylaxis and treatment for malaria, the use of azithromycin as an alternative in the self-treatment of traveler's diarrhea, and the combination of hepatitis A and hepatitis B vaccines. At the same time, new challenges continue to appear. Shifts in the distribution of infections, such as West Nile virus and dengue fever, underscore the need for up-to-date information. Well-known infectious diseases, such as polio, meningococcal meningitis, and influenza are appearing in unexpected ways and settings. It is increasingly clear that travelers, while at risk for infections, also play a role in the global dispersal of pathogens, such as certain serogroups of Neisseria meningitidis and influenza. Increasing drug resistance affects the choice of drugs for treatment and chemoprophylaxis, and decisions about use of vaccines. Newly identified adverse events associated with yellow fever vaccine have prompted enhanced surveillance after vaccination and careful scrutiny of appropriate indications for the vaccine.

Ineffectiveness of the current strategy to prevent hepatitis A in travelers

BACKGROUND

Each year, a large number of Canadians travel to regions of the world where hepatitis A remains endemic. Many of these travelers are not immune and the current preventive strategy relies wholly on self-referral to a travel clinic. All of the costs associated with such a visit are assumed by the traveler. We estimated the effectiveness of this strategy.

METHODS

This case-control study included 108 travel-related hepatitis A cases with onset of disease between 1997 and 1999 and 620 controls who traveled during the same period.

RESULTS

Hepatitis A was strongly associated with high-risk travel (Odds Ratio = 7.2, 95% Confidence Interval 1.76-29.4), but only 7% of cases were found in this category. The risk of hepatitis A was 5 times lower in travelers who visited a travel clinic than in those who did not (80% efficacy). However, only 14% of the controls visited a travel clinic. As a result, the effectiveness of the current strategy is estimated to be 11% (80% of 14%).

CONCLUSIONS

Hepatitis A in travelers can be prevented effectively by attendance at a travel clinic. Unfortunately, most travelers do not visit such clinics prior to departure. Even if all high-risk travelers were to visit a travel clinic and receive vaccination, this would have negligible impact on the number of travel-related hepatitis A cases (approximately 7% reduction). The current strategy for the prevention of hepatitis A in travelers is ineffective and should be reexamined.