Risks of hepatitis B for travellers

Vaccines and Senior Travellers

Background: International tourist travel has been increasingly steadily in recent years, and looks set to reach unprecedented levels in the coming decades. Among these travellers, an increasing proportion is aged over 60 years, and is healthy and wealthy enough to be able to travel. However, senior travellers have specific risks linked to their age, health and travel patterns, as compared to their younger counterparts.

Methods: We review here the risk of major vaccine-preventable travel-associated infectious diseases, and forms and efficacy of vaccination for these diseases.

Results: Routine vaccinations are recommended for older persons, regardless of whether they travel or not (e.g., influenza, pneumococcal vaccines). Older individuals should be advised about the vaccines that are recommended for their age group in the framework of the national vaccination schedule. Travel-specific vaccines must be discussed in detail on a case-by-case basis, and the risk associated with the vaccine should be carefully weighed against the risk of contracting the disease during travel. Travel-specific vaccines reviewed here include yellow fever, hepatitis, meningococcal meningitis, typhoid fever, cholera, poliomyelitis, rabies, Japanese encephalitis, tick-borne encephalitis and dengue.

Conclusion: The number of older people who have the good health and financial resources to travel is rising dramatically. Older travellers should be advised appropriately about routine and travel-specific vaccines, taking into account the destination, duration and purpose of the trip, the activities planned, the type of accommodation, as well as patient-specific characteristics, such as health status and current medications.

Risk of hepatitis B when migrating from low to high endemic areas

Prevalence of hepatitis B virus (HBV) infections varies markedly with geography and is endemic in the Arctic. Travel and migration have increased markedly while the influence of migration to high endemic areas remains unknown. We surveyed subjects migrating from an area with a low prevalence of chronic HBV infection (Denmark, 0.01%) to an endemic HBV area (West- and East Greenland, 3% and 29%) in order to describe the prevalence of HBV exposure among migrants. We included 198 Caucasian Danes that had migrated to Greenland and repeated the cross-sectional investigation after 10 years. We performed thorough serological testing for HBV. None had ongoing HBV infection. Migrants to East Greenland were more frequently exposed to HBV than those in West Greenland (34.3% vs 10.3%; p < 0.01). This difference was reduced at 10-year follow-up (8.1% vs 5.7%; ns) and the overall number of participants with past HBV infection decreased over the 10-year period from 19.4% to 6.9% (p = 0.02). In conclusion, migration from very low prevalence to endemic HBV areas associated with a markedly increased risk of exposure to HBV. Lack of vaccination among migrants from Denmark to Greenland was frequent and it poses a continuing risk. All who migrate from low to high endemic HBV areas should be vaccinated.

Abbreviations

HBV: Hepatitis B virus; HBV-DNA: Hepatitis B virus deoxyribonucleic acid; HBsAg: Hepatitis B surface antigen; Anti-HBs: Antibodies against hepatitis B surface antigen; Anti-HBc: Antibodies against hepatitis B core antigen; BMI: Body mass index

Vaccine-preventable travel health risks: what is the evidence--what are the gaps?

BACKGROUND

Existing travel health guidelines are based on a variety of data with underpinning evidence ranging from high-quality randomized controlled trials to best estimates from expert opinion. For strategic guidance and to set overall priorities, data about average risk are useful. The World Health Organization (WHO) plans to base future editions of "International Travel and Health" on its new "Handbook for Guideline Development."

METHODS

Based on a systematic search in PubMed, the existing evidence and quality of data on vaccine-preventable disease (VPD) risks in travelers was examined and essentials of vaccine efficacy were briefly reviewed. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework was used to evaluate the quality of the data.

RESULTS

Moderate-quality data to determine the risk of VPD exist on those that are frequently imported, whereas in most others the level of confidence with existing data is low or very low.

CONCLUSIONS

In order for the WHO to produce graded risk statements in the updated version of "International Travel and Health," major investment of time plus additional high-quality, generalizable risk data are needed.

Management of acute hepatitis B

Acute hepatitis B virus (HBV) is a common cause of acute icteric hepatitis in adults. The vast majority of these patients resolve this acute infection and develop long-lasting immunity. In contrast, the vast majority of patients who develop chronic HBV have minimal symptoms and do not develop jaundice after becoming infected with HBV. These patients will frequently remain undiagnosed for years or decades. Approximately 1% of persons with acute HBV develop acute liver failure. Preventing acute HBV with vaccination is the best treatment. Although universal vaccination is now administered to newborns in many countries, the majority of adults have not been vaccinated and remain at risk. Because the majority of patients with acute HBV resolve this infection spontaneously, treatment with an oral anti-HBV agent is not necessary. However, the use of an oral anti-HBV agent is not unreasonable to use in a patient who is developing acute liver failure from severe acute HBV.

Risk of hepatitis B for travelers: is vaccination for all travelers really necessary?

OBJECTIVES

Behavioral studies in travelers suggest that 33% to 76% of all travelers to hepatitis B virus (HBV)-endemic countries are at risk for HBV infection. We study the incidence and risk factors for HBV infection in travelers.

METHODS

Retrospective analysis of the characteristics and risk factors of all reported acute HBV patients in Amsterdam, the Netherlands, from January 1, 1992, until December 31, 2003.

RESULTS

The estimated incidence in travelers from Amsterdam to HBV-endemic countries is 4.5/100,000 travelers. Two thirds of these patients were immigrants who lived in Amsterdam and who had visited their friends and relatives in their country of origin. In 12 years, only three Dutch short-term tourists contracted HBV while traveling, all by heterosexual contacts.

CONCLUSIONS

Dutch tourists who travel to HBV-endemic countries run a very low risk of contracting HBV. Vaccination of short-term Dutch tourists is not necessary. Immigrants run a higher risk irrespective of travel or duration of travel. This group should be advised vaccination.

Hepatitis B risks and immunization coverage among American travelers

BACKGROUND

Hepatitis B is endemic in much of Asia, Africa, and parts of South America, regions that are increasingly popular destinations for American travelers. The frequency of hepatitis B risks during travel has been examined for Europeans but not Americans. Further, limited data are available to describe the domestic hepatitis B risk factors of American travelers, the proportion vaccinated, and whether immunization activities target travelers at highest risk. We conducted a survey of international travelers to address these issues.

METHODS

A survey was mailed to 884 American international travelers, of whom 618 (70%) responded. The survey covered demographic and travel characteristics, sources of pre-travel health advice, immunization status, and items needed to assess hepatitis B vaccination candidacy. Travel-specific items concerned the most recent trip to a hepatitis B endemic region. Hepatitis B risk during the most recent trip was classified as high, potential, or none based on potential exposure to blood or bodily fluids.

RESULTS

Only 31% of respondents visited any health practitioner to obtain pre-travel health advice; 13% visited a travel medicine specialist. Totally 45% of respondents reported (3)1 domestic or travel-related hepatitis B risk, and 8% were at high risk during travel. Risk factors were more common among younger travelers and those with longer travel durations. Travel medicine specialists were more likely than nonspecialists to provide hepatitis B vaccine (40% vs 21%, p= 0.01). Travelers with risk factors were no more likely to be vaccinated in specialist or nonspecialist settings. Upon departure, only 19% of all travelers and 30% of travelers with risk factors had received three or more hepatitis B vaccine doses.

CONCLUSIONS

Most US travelers to hepatitis B endemic regions do not secure pre-travel health advice, and most have not received three doses of hepatitis B vaccine. A substantial share are candidates for hepatitis B vaccination based on their domestic activities, and/or face hepatitis B risks during travel.

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.

Prevention of infectious diseases among international pediatric travelers: considerations for clinicians

An estimated 1.9 million children travel overseas annually. Infectious disease risks associated with international travel are diverse and depend on the destination, planned activities, and baseline medical history. Children have special needs and vulnerabilities that should be addressed when preparing for travel abroad. Children should have a pretravel health assessment that includes recommendations for both routine and special travel-related vaccination; malaria chemoprophylaxis, if indicated; and prevention counseling regarding insect and animal exposures, food and water safety, and avoiding injuries. Special consideration should be given to children with chronic diseases. Families should be given anticipatory guidance for management of potential illnesses and information about the location of medical resources overseas.

Risks of hepatitis B in travelers as compared to immunization status

BACKGROUND

Our objective was to determine the risks of infection with hepatitis B among European travelers and to compare this with the immunization status in various risk groups.

METHODS

A cross-sectional telephone questionnaire survey of randomly selected subjects, in nine European study populations was used. A total of 9, 008 individuals were involved, with approximately 1,000 interviews conducted in each country in the native languages. Situations with a high risk of hepatitis B infection, such as invasive medical procedures, attending to a bleeding person, and skin perforating cosmetic practices, particularly when performed in countries with medium/high transmission risk, and vaccination status of travelers, were the main outcome measures.

RESULTS

Depending upon the destination, 6.6-11.2% of travelers were classified as at high risk of hepatitis B, with 24.4% vaccinated; between 60.8-75.8% of travelers at potential risk, with 19.2% vaccinated; and 33.4% of travelers where no hepatitis B risk was identified. Significantly more travelers who only visited medium/high endemicity regions exposed themselves to a high risk of contracting hepatitis B, (40, 10.5%) compared to travelers who only visited low endemicity regions (225, 6.6%; p <.01).

CONCLUSIONS

A significant proportion of travelers surveyed unwittingly exposed themselves to the risk of hepatitis B infection while at medium/high risk destinations. The majority of at-risk travelers had not been vaccinated, regardless of their destination. Improved advice and clear recommendations to avoid transmission are needed.

Incidence of and risk factors for hepatitis A in Italy: public health indications from a 10-year surveillance. SEIEVA Collaborating Group

BACKGROUND/AIMS

This study aimed to evaluate the incidence of and risk factors for acute viral hepatitis A (HAV) in Italy.

METHODS

Data were from a surveillance system for type-specific acute viral hepatitis (SEIEVA). To estimate the association of hepatitis A cases with the potential risk factors (Odds Ratios) and the proportion of all hepatitis A cases attributable to a given risk factor (population attributable risk), hepatitis B cases were used as controls. Independent predictors of HAV were estimated by conditional multiple logistic regression.

RESULTS

During the period 1985-1994, 25553 viral hepatitis cases were reported. Of these, 6408 (25%) were due to hepatitis A (HAV). HAV incidence declined from 10/100000 in 1985 to 2/100000 in 1987. Since 1991, however, an increase in HAV has been observed. The majority of cases were 15-24 years old; the incidence was higher in males and in subjects residing in southern Italy. Only one death (0.02%) was observed. Shellfish consumption was the most frequently reported risk factor (62%). The proportion of cases reporting personal contact with an icteric case, travel to a high-medium endemic areas, and family contact with a child attending a day-care centre (household of day-care child) was 17%, 19% and 15%, respectively. The results of multivariate analysis showed that shellfish consumption (OR=2.6; 95% CI=2.4-2.9), travel to endemic areas for people residing in northern and central Italy (OR=5.4; 95% CI=4.6-6.2) and household of day-care child (OR=1.2; 95% CI=1.03-1.4), were all types of exposure independently associated with HAV. The estimates of population-attributable risk show that shellfish consumption explained as many as 42.2%, travel to high-medium endemic areas for people residing in northern and central Italy 24.2%, and household of day-care child only 1.4% of all acute hepatitis A cases in Italy.

CONCLUSIONS

These findings indicate that HAV in Italy is mainly a food-borne disease. Vaccination against hepatitis A is strongly recommended for travellers to endemic areas.

Significance of imported hepatitis B virus infections

The risk of imported hepatitis B in Germany and comparable European countries seems to be low as long a suitable control measures are taken. These measures include testing for hepatitis B markers of immigrants from highly endemic areas as well as of individuals who stayed for a longer period of time in such regions, information of chronic carriers of hepatitis B virus and vaccination of their contacts, and vaccination of travellers to endemic regions who run an increased risk for contracting hepatitis B as e.g. i.v drug users or sex tourists.

Hepatitis A and hepatitis B: risks compared with other vaccine preventable diseases and immunization recommendations

The incidence rate of hepatitis A is 3(-6)/1000 per month of stay in a developing country in unprotected travellers. Tramps and other persons feeding themselves under bad hygienic conditions have a rate of 20/1000. In many industrialized countries, persons below the age of 50 years have a seroprevalence rate of anti-HAV < 20%. Hepatitis A morbidity and mortality rates in travellers are far greater than those of any other vaccine-preventable infection in travellers, with the exception that hepatitis B shows a slightly greater mortality rate in expatriates. Future studies will determine the role of hepatitis C and E. Typhoid fever shows an incidence rate of 0.3/1000 in foreigners on the Indian subcontinent, and in many parts of North and West Africa, excluding Tunisia; in other parts of the Third World it is tenfold lower. In poliomyelitis, tetanus, diphtheria, cholera, rabies and Japanese encephalitis the incidence rate is < or = 0.002/1000.

Risk of hepatitis A in travellers

A review of the literature shows that 30-35 million travellers from industrialized nations annually visit a developing country where their incidence rate of symptomatic hepatitis A is 3 to 6 per 1000 per month of stay if they remain unprotected. The risk is 20 per 1000 for persons eating and drinking under poor hygienic conditions. Thus hepatitis A is now the most frequent vaccine-preventable disease in such travellers. Antibodies to hepatitis A virus are rarely found in potential travellers in many industrialized countries, except in those born before 1944, in those with a history of jaundice, or in those with a stay > 1 year in a developing country.

Travel medicine--prevention based on epidemiological data

In travel medicine efforts should be concentrated on preventive measures that are necessary, and travellers should be spared the side effects, costs and stress of superfluous measures. Excess mortality abroad is mainly due to traffic and swimming accidents, indicating the need for appropriate control strategies. The morbidity in travellers to developing countries is high, and is primarily due to traveller's diarrhoea. As prophylaxis is ineffective or unrealistic, and as travellers often need fast relief, it is recommended to include loperamide and an antimicrobial agent in the travel kit. Recent studies have shown that the incidence rate per month of Plasmodium falciparum malaria in Africa may reach 24/1000. The most frequently occurring immunizable diseases are hepatitis A (3/1000) and hepatitis B (0.8/1000). For many tourists and some expatriates pre-travel advice (hygiene, measures against mosquito bites, etc.) as well as chemoprophylaxis and immunization can be limited to these infections, but those travelling or staying outside large centres need additional measures.