An estimate of the incidence of hepatitis A in unimmunized Canadian travelers to developing countries

Economic evaluation of a publicly funded hepatitis A travel vaccination program in Ontario, Canada

BACKGROUND

Hepatitis A virus (HAV) causes acute liver infection and is spread through the fecal-oral route. Travel to countries in HAV-endemic regions (e.g., Asia and Latin America) is a well-described risk factor for infection. Currently, Ontario publicly funds hepatitis A vaccination for some populations at high risk of HAV infection but not for all travellers to endemic countries. The objective of this study was to determine the cost-effectiveness of expanding publicly funded HAV vaccination to people planning travel to HAV-endemic regions, from the Ontario healthcare payer perspective.

METHODS

We conducted a cost-utility analysis comparing an expanded high-risk publicly-funded hepatitis A vaccination program including funded vaccine for travellers to endemic regions to the current high risk program in Ontario. A Markov state transition model was developed, including six possible health states. Model parameters were informed through targeted literature searches and included hepatitis A disease probabilities, utilities associated with health states, health system expenditures, and vaccine costs. Future costs and health outcomes were discounted at 1.5%. Primary outcomes included cost, incremental cost-effectiveness ratio (ICER) and quality adjusted life years (QALYs) over a lifetime time horizon. We conducted one-way, two-way, and probabilistic sensitivity analysis.

RESULTS

The expanded high risk HAV vaccine program provided few incremental health gains in the travel population (mean 0.000037 QALYs/person), at an incremental cost of $124.31. The ICER of the expanded program compared to status quo is $3,391,504/QALY gained. The conclusion of the model was robust to changes in key parameters across reasonable ranges.

CONCLUSIONS

The expanded vaccination program substantially exceeds commonly accepted cost-effectiveness thresholds. Further research concerning possible cost-effective implementation of high-risk travel hepatitis A vaccination should focus on a more integrated understanding of the risk of acquiring hepatitis A during travel to endemic regions (e.g., purpose, length of stay).

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.

Hepatitis A risk in travelers

BACKGROUND

Traveling to highly endemic areas for hepatitis A is increasing while the immunization level in travelers has been shown to be low in the countries studied.

METHODS

In this population-based study, we have estimated the incidence rate of travel-related hepatitis A during 1997 to 2005 by use of the Swedish notification system of communicable diseases and an ongoing national database on travel patterns. We have also acquired airport-based immunization data from 2007.

RESULTS

During the study period, 636 cases of travel-related hepatitis A were notified. Traveling to East Africa was associated with the highest incidence rate (14.1 cases/100,000 person months), followed by the Middle East (5.8/100,000 person months), and India with neighboring countries (5.6/100,000 person months). Visiting Friends and Relatives (VFR) travelers represented 83, 91, and 70% of the cases to these three regions. By age-group, the highest incidence was found in children 0 to 14 years (3.1/100,000 travelers) where 88% of the cases were VFR travelers. Incidence rate in unprotected travelers to East Asia, North Africa, and the Middle East was 2, 12, and 18 cases/100,000 person months, respectively. In 2007, 79% of the travelers were immunized against hepatitis A.

CONCLUSIONS

We conclude that travelers, and especially children, who are VFR in endemic areas constitute a high-risk group for acquiring hepatitis A infection, while the risk for unprotected tourists to East Asia is low.

Hepatitis A among Danish travellers 1980-2007

The authors present a descriptive study on hepatitis A among Danish travellers in the period 1980-2007 based on data from a large survey among 26,640 Danes regarding travel habits, as well as national surveillance and population data. There are five messages to be read from the results: (1) The incidence of hepatitis A is declining at most destinations worldwide. (2) Reported incidence rates tend to overestimate the risk for the average tourist because they include immigrants visiting friends and family in the country of origin. (3) The immunization strategy in Denmark (leaving it up to the individual traveller to seek advice and pay for the immunization) seems to work well for most Danish travellers as 75% travelled immune. (4) Danes travel very frequently to hepatitis A endemic areas and will spend on average 6 months in endemic areas from the age of 18 till 79. (5) 80% of all incident cases 2002-2006 were immigrants or children of immigrants. The immunization strategy is not effective in this group. In conclusion, the risk of acquiring hepatitis A abroad is low for the average ethnic Danish tourist, while it is high in immigrants and their children. Thus, special focus on this group of travellers is warranted.

Spanish travelers to high-risk areas in the tropics: airport survey of travel health knowledge, attitudes, and practices in vaccination and malaria prevention

OBJECTIVE

To evaluate travel health knowledge, attitudes, and practices on vaccination and malaria prevention among Spanish travelers to the tropics.

METHODS

A cross-sectional survey was carried out in the departure lounge of the two main Spanish international airports in the summer of 2004. A questionnaire was administered to 1,206 Spanish citizens traveling to high-risk areas of tropical South America, 635 travelers (52.6%); Southeast Asia, 251 (20.8%); Sub-Saharan Africa, 181 (15.0%), and the Indian subcontinent, 139 (11.6%). Risk areas were defined according to published sources. Travelers were asked about their attitudes to travel vaccines and malaria prophylaxis and whether they had received either or both on this or previous trips. Adequate malaria prophylaxis was considered as the correct drugs for the destination as indicated by the World Health Organization.

RESULTS

Fifty-eight percent of travelers were male and the mean age was 38 years. Thirty-six percent were traveling to tropical areas for the first time. The main reason for travel was tourism (82%) or business (12%). The mean time preparing the trip was 39 days; 73% looked for information a mean of 19 days in advance and 54% were advised in travelers' clinics. Fifty-five percent received no travel vaccines. A total of 48.1% of tourists and 30.1% of business travelers were vaccinated (p<0.00006). The most frequent vaccines administered were as follows: typhoid fever, 32%; yellow fever, 29%; tetanus-diphtheria, 24%; and hepatitis A, 14%. Malaria prophylaxis was taken by 422 travelers including mefloquine (44%), atovaquone-proguanil (17%), chloroquine (16%), chloroquine-proguanil (15%), doxycycline (3%), and unknown (5%).

CONCLUSIONS

More than half of travelers to risk areas received no vaccinations before the trip. More than a third of travelers to Sub-Saharan Africa received no malaria prophylaxis.

Epidemiology of travel-associated and autochthonous hepatitis A in Austrian children, 1998 to 2005

BACKGROUND

In Austria, being an area of low hepatitis A endemicity, every year, several cases of this infectious disease are reported. The aim of the present study was to provide data on disease and hospitalization of children below the age of 15 for imported and autochthonous hepatitis A in Austria.

METHODS

Nationwide, active, hospital-based surveillance during the period 1998 to 2005.

RESULTS

During this 8-year observation period, 413 children below 15 years of age were hospitalized with acute hepatitis due to infection with hepatitis A . The mean annual incidence of hospitalization per 100,000 population was 3.8, with a decreasing trend from 1998 to 2005. The mean length of hospital stay attributable to hepatitis A was 6.5 days. The mean annual number of days of hospitalization attributable to acute hepatitis A infection in children below 15 years of age was 335 days. Information on origin of infection was available in 48% of the reports, the majority of which (69%) were in consequence of infection import. The mean annual incidence of travel-associated, hospitalized hepatitis A cases was 1.3 per 100,000, showing a lesser decrease rate over the observation period than the total hospitalization incidence.

CONCLUSIONS

In an area of low hepatitis A endemicity such as Austria, hospitalization incidence of children is still at a considerable level. Our findings contribute to an open discussion about universal childhood vaccination.

Pretravel advice and hepatitis A immunization among Australian travelers

BACKGROUND

More Australians are traveling to overseas destinations where preventable infectious diseases, such as hepatitis A, are endemic. Yet, there is only limited data concerning the extent to which Australians seek travel advice and vaccination before their departures.

METHOD

Annual telephone surveys were conducted among adult Australians travelers. Information was collected on the travel advice and vaccinations received before departure. Perceptions about, and their potential exposure to, travel-related infections while overseas were also assessed. This paper presents data from the 2003 survey related to travel advice and hepatitis A, while hepatitis B is discussed in the companion article.

RESULTS

Only a third of interviewees had sought health advice before travel. Infrequent travelers, those departing for endemic countries or for longer journeys, were more likely to seek medical advice. Overall, 32% of interviewees had been vaccinated against hepatitis A, with travelers to high/medium-hepatitis A endemicity destinations being more likely to be vaccinated than those visiting low-endemicity countries (44% vs 20%). Among the 263 visitors to endemic countries, those who stayed with friends and relatives were least likely to be vaccinated against hepatitis A compared to other styles of accommodation.

CONCLUSIONS

Despite government recommendations and industry group campaigns about the need for pretravel advice, the majority of Australians travel overseas without adequate health advice and protection against hepatitis A and other travel-related infectious diseases.

Hepatitis A, typhoid and malaria among travelers--surveillance data from Québec (Canada)

Analysis of epidemiological data on health problems related to international travel helps put into perspective preventive interventions for travelers. To document the epidemiological context of travel health interventions in Québec, we reviewed surveillance data for three infectious diseases. The analysis included data collected in the notifiable diseases surveillance system for hepatitis A, typhoid, and malaria cases reported from 2000 to 2002. Additional data were obtained from the provincial hepatitis risk factor database as well as from regional public health departments. More than 40% of cases of hepatitis A for which risk factor information is available are associated with international travel; 20% of these cases were contracted in Mexico and 22% in the West Indies. The risk of acquiring hepatitis A seems to be higher among travelers under 35 years of age; also, given the number of Quebecers traveling to all regions of the world, this risk is proportionally higher in Africa. Data gathered for typhoid indicate that the risk to travelers from Québec is proportionately higher for Quebecers traveling to the Indian subcontinent and whose purpose is to visit family and friends, and for those who stay abroad for 4 weeks or longer. The risk of malaria is greater in Africa (where contracted cases are mostly caused by Plasmodium falciparum). Over half of malaria cases involve individuals traveling abroad for business (including volunteerism), and almost 75% contracted the disease during a stay of a month or more. Nearly half of the cases had not taken chemoprophylaxis. Available data have limitations for infectious disease surveillance among Québec travelers: imprecise number of cases (underdiagnosis and underreporting), imprecise denominators (number of travelers), and lack of data on the characteristics of trips taken. However, despite its limitations, this profile of infectious diseases among travelers from Québec provides interesting data for preventive intervention.

Immunity to hepatitis A and hepatitis B in Indian and Chinese immigrants seen in a travel clinic in Massachusetts, United States

Immigrants to the United States from developing countries have a higher probability of previous infection with hepatitis A virus (HAV) and/or hepatitis B virus in their countries of origin. Prior knowledge of hepatitis A and B seroprevalence in this population may aid in determining the need for pretravel immunizations when these individuals travel to endemic regions. We conducted a retrospective analysis of hepatitis A and B serologies in a travel clinic population (from March 1999 through September 2002) to determine the seroprevalence in our predominantly highly educated foreign-born subjects. All our patients who had immigrated from China and India and who were older than 60 years (born on or before 1940) were immune to hepatitis A. The Indian and Chinese subjects who were anti-HAV positive were also significantly older than the anti-HAV negative group. In addition, in our Indian study group, the hepatitis A-seropositive individuals first left India at a significantly older age than the hepatitis A-seronegative group (mean age 22.7 years vs 11.4 years, p < 0.05). Our small sample size of Chinese subjects may not have permitted a statistically significant difference to be detected for hepatitis A seroprevalence and age at departure from their country of origin. These results have helped tailor our recommendations for pretravel immunizations for our groups of foreign-born individuals planning to visit endemic areas. Individuals born in China or India on or before 1940 are likely to have preexisting antibody to hepatitis A and probably do not need the vaccine when they travel. Younger individuals may elect to have a hepatitis A antibody titer checked before getting the vaccine.

Hepatitis A Virus Infections in Travelers, 1988-2004

BACKGROUND

Uncertainty exists about the current risk of hepatitis A virus infection in nonimmune travelers to destinations with high or intermediate risk of transmission. We analyzed recent epidemiological data on imported hepatitis A to determine region-specific attack rates and incidences.

METHODS

Surveillance data on hepatitis A virus infections diagnosed during 1988-2004 were evaluated on the basis of notification by laboratories, additional reports of physicians, and traveler's statistics. This study focuses on international travelers with hepatitis A virus infection detected after their return to Switzerland.

RESULTS

The rate of imported hepatitis A virus infections decreased 75% from 1988 to 2004 and accounted overall for 42% of all hepatitis A cases reported in Switzerland. The actual incidence of hepatitis A in travelers to countries of high or intermediate risk of transmission was 3.0-11.0 per 100,000 person-months abroad for all travelers and 6.0-28.0 per 100,000 for those presumed to be nonimmune. The actual proportion of those visiting friends and relatives among patients with hepatitis A has increased to 28.2%, with children aged 0-14 years predominating. Reductions in the incidence by hepatitis A vaccination were estimated to vary between 35.0% and 61.8% for different destinations.

CONCLUSIONS

The risk of hepatitis A virus infections has decreased by a factor of 10-50-fold over time, compared with findings from older studies. The risk, however, remains very considerable at many destinations, including frequently visited places, such as Mexico. Children of immigrants are a high-risk population. Strategies are needed to reach those at highest risk.

Changing travel-related global epidemiology of hepatitis A

Hepatitis A is highly endemic in many emerging cultures. Despite the availability of safe and effective vaccines and some improvements in sanitation in developing countries, hepatitis A remains a significant cause of morbidity for nonimmune travelers visiting such destinations. All are at risk, including short-term vacationers or business travelers who stay in deluxe accommodations. This may have considerable implications on public health. Hepatitis A vaccination programs for travelers have not proven to be effective, since many visitors to destinations at risk (e.g., Mexico) fail to consult health professionals prior to departure. Because 50% of the US population has an anticipated lifetime risk for exposure, universal immunization against hepatitis A should be considered.

Nationwide canadian study of hepatitis a antibody prevalence among children eight to thirteen years old

BACKGROUND

Hepatitis A vaccines provide consistent, long-lasting protection and have been available for almost 10 years in Canada, but their use remains limited. It is difficult to assess their optimal utilization given that our knowledge of hepatitis A epidemiology in Canada is fragmentary. Unlike the United States, no nationwide study of hepatitis A prevalence has ever been done in Canada. Consequently we do not know the incidence of infection in children and what would be the most appropriate age for hepatitis A vaccination.

OBJECTIVE

To estimate the proportion of 8- to 13-year-old children who have been infected with hepatitis A virus (HAV) and the risk factors for this infection on a nationwide scale.

METHODS

Children were sampled in 10 Canadian provinces, comprising 5 regions, using random digit dialing methodology with regional stratification. Demographic data and information about risk factors for hepatitis A were collected by the telephone interviewers. Oral fluid samples were self-collected and mailed to the laboratory, where they were tested for anti-HAV IgG.

RESULTS

Of 6740 contacted families with a child of required age, 1688 (25%) agreed to participate and answered the questionnaire. From these, 1074 oral fluid samples were received, and 1057 could be analyzed. Anti-HAV IgG was detected in 2.7% of subjects, with variation by region from 0.8 to 3.4%. The parents of 54 subjects (5.1%) reported that their child had previously been vaccinated against HAV. Anti-HAV IgG was present in 2.0% of unvaccinated subjects, among whom antibody prevalence was 19.4% in children born in HAV-endemic countries, 6.1% in Native children and 4.2% in travelers to endemic countries. In multivariate analysis of all subjects, the presence of anti-HAV IgG was significantly associated with birth in an endemic country, travel to an endemic country, Native status (American Indian and Inuit population), female gender and vaccination against HAV. In nonvaccinated, non-Native children born in Canada who did not travel to endemic countries, anti-HAV prevalence was 1.1%.

CONCLUSIONS

The risk for hepatitis A during childhood is low in Canada. Almost all teenagers (>97%) would be at risk for infection in case of contact with HAV. Changes in immunization policy against hepatitis A should be considered.

Overlapping epidemiologies of hepatitis A and typhoid fever: the needs of the traveler

Hepatitis A and typhoid fever are endemic infectious diseases in many parts of the world. They share a common, simple mode of transmission--the fecal--oral route-associated with poor hygiene. The low endemicity of both diseases in developed countries, and the rise in travel to exotic destinations for business and leisure, mean that increasing numbers of travelers are being exposed to infection. Effective, established vaccines are available against both diseases, and recently new formulations combining both vaccines in one injection have been licensed. We review the present epidemiologic situation for both diseases, to determine the necessity to routinely vaccinate travelers against both diseases.