Changing risk profile of hepatitis A in The Netherlands: a comparison of seroprevalence in 1995-1996 and 2006-2007

Ethnic differences in hepatitis A and E virus seroprevalence in patients attending the Emergency Department, Paramaribo, Suriname

BACKGROUND

Hepatitis A virus (HAV) and hepatitis E virus (HEV) have enteric modes of transmission and are common causes of acute hepatitis in low- and middle-income countries. HEV is also characterised as a zoonotic infection and is prevalent in high-income countries. Data on HAV and HEV prevalence in Suriname, a middle-income country in South America, are scarce.

METHODS

Serum samples of 944 and 949 randomly selected patients attending the Emergency Department at the Academic Hospital of Paramaribo, the capital of Suriname, were analysed for anti-HAV antibodies (anti-HAV) and anti-HEV antibodies (anti-HEV), respectively. Determinants of anti-HAV and anti-HEV positive serology were evaluated using multivariable logistic regression.

RESULTS

Anti-HAV prevalence was 58.3% (95% CI 55.4 to 61.4%) and higher prevalence was independently associated with belonging to the Tribal or Indigenous population and older age. Anti-HEV prevalence was 3.7% (95% CI 2.6 to 5.0%) and higher prevalence was associated with Tribal and Creole ethnicity and older age.

CONCLUSIONS

In Suriname, exposure to HAV is consistent with a very low endemic country and exposure to HEV was rare. Both viruses were more prevalent in specific ethnic groups. As anti-HAVantibodies were less frequently found in younger individuals, they could be susceptible to potential HAV outbreaks and might require HAV vaccination.

Determinants of hepatitis A infection among students: A case study of an outbreak in Jember, Indonesia

BACKGROUND

Hepatitis A often occurs in school among students in the form of an outbreak. The transmission was through fecal-oral (Common Source) provided that the epidemic curve is close to propagated. The aim of the current study was to analyze the determinants of Hepatitis A Infection among students. Design and methods: This study was a case-control study which was conducted at SMAN Plus with a sample size of 80 students chosen by using simple random sampling. The data obtained were then analyzed using logistic regression with 95% confidence level (α = 0.05), while the strength of the relationship between variables was identified using Odds Ratio (OR).

RESULTS

 Most of the students were at the age of 17 to 19 years old (65%) and male (57.5%). The average age in the case group was 17.1 years old, while in the control group was 16.75 years old. The habit of consuming raw foods (p = 0.001) as well as eating and drink at the same time during an activity (p = 0.000) had a significant influence on the outbreak of Hepatitis A in the curve epidemic of common source.

CONCLUSIONS

 The outbreak is confirmed as a transmission occurs through fecal-oral which the common source epidemic curve. Risk factors that have been proven to be related to Hepatitis A include consuming raw food, eating shared meals during an activity, and drinking with shared drinking utensils.

Adherence to hepatitis A travel health guidelines: A cross-sectional seroprevalence study in Dutch travelling families - The Dutch travel Vaccination Study (DiVeST)

BACKGROUND

This Dutch travel Vaccination Study (DiVeST) aimed to study adherence or compliance to Dutch travel health guidelines in travelling families and to identify risk groups to provide better advice and protection for international travellers.

METHODS

Between 2016 and 2018, family members who travelled to Eastern Europe or outside Europe during the preceding year were recruited via Dutch secondary schools. The vaccination status of the travellers was assessed using questionnaires and vaccination records and hepatitis A virus antibody concentrations in dried blood spot (DBS) eluates. Subgroups of travellers with lower adherence to guidelines were identified.

RESULTS

Of the 246 travellers that participated in this study, 155 (63%) travelled to destinations for which the HAV vaccination was recommended. Of these 155 travellers, 56 (36%) said they visited a pre-travel clinic, and 64 of them (41%) showed a valid HAV vaccination in their vaccination records. Of the 145 travellers with available DBS eluates, anti-HAV antibodies were detected in 98 (68%) of them.

CONCLUSIONS

We found that adherence to travel health guidelines, in terms of HAV vaccination, was suboptimal. According to our results, specific attention should be paid to children, persons visiting friends and relatives and those who travel relatively short distances.

Hepatitis A vaccine immunogenicity in patients using immunosuppressive drugs: A systematic review and meta-analysis

INTRODUCTION

Inactivated hepatitis A (HepA) vaccines are very immunogenic in healthy individuals; however, it remains unclear how different immunosuppressive regimens affect HepA vaccine immunogenicity. Our objective was to summarise the current evidence on immunogenicity of HepA vaccination in patients using immunosuppressive drugs.

METHODS

We systematically searched the literature for studies on immunogenicity of inactivated HepA vaccines in adults using immunosuppressive drugs. Studies reporting seroconversion rates (SCR) 4-8 weeks after 1 and 2 doses of HepA vaccine in organ transplant recipients and patients with chronic inflammatory conditions were included in a meta-analysis.

RESULTS

We included 17 studies, comprising 1,332 individuals. In healthy controls (2 studies), SCRs were 90-94% after the first dose and 100% after the second dose. In organ transplant recipients, SCRs ranged from 0 to 67% after the first dose of vaccine and 0-97% after the second dose. In patients with chronic inflammatory conditions, SCRs ranged from 6% to 100% after the first dose and from 48 to 100% after the second dose of vaccine. Patients using a TNF-alpha inhibitor versus conventional immune-modulators (e.g. methotrexate, azathioprine, corticosteroids) were more likely to seroconvert after the first dose of vaccine (OR12.1 [2.14-68.2]) but not after the second dose of vaccine (OR 0.78 [0.21-2.92]) in a meta-analysis.

CONCLUSION

Studies evaluating HepA vaccine immunogenicity in immunosuppressive agents are heterogeneous. Overall, there is an impaired immune response following HepA vaccination in patients using immunosuppressive drugs, especially after only one dose of vaccine and in organ transplant recipients. HepA vaccination should therefore be considered before immunosuppressive therapy. Future research should focus on alternative vaccination regimens and long-term immunogenicity.

PROSPERO ID

CRD42018102607.

Immunity against measles, mumps, rubella, varicella, diphtheria, tetanus, polio, hepatitis A and hepatitis B among adult asylum seekers in the Netherlands, 2016

Asylum seekers are a vulnerable population for contracting infectious diseases. Outbreaks occur among children and adults. In the Netherlands, asylum seeker children are offered vaccination according to the National Immunization Program. Little is known about protection against vaccine-preventable diseases (VPD) in adult asylum seekers. In this 2016 study, we assessed the immunity of adult asylum seekers against nine VPD to identify groups that might benefit from additional vaccinations. We invited asylum seekers from Syria, Iran, Iraq, Afghanistan, Eritrea and Ethiopia to participate in a serosurvey. Participants provided informed consent and a blood sample, and completed a questionnaire. We measured prevalence of protective antibodies to measles, mumps, rubella, varicella, diphtheria, tetanus, polio type 1-3 and hepatitis A and B, stratified them by country of origin and age groups. The median age of the 622 participants was 28 years (interquartile range: 23-35), 81% were male and 48% originated from Syria. Overall, seroprotection was 88% for measles (range between countries: 83-93%), 91% for mumps (81-95%), 94% for rubella (84-98%), 96% for varicella (92-98%), 82% for diphtheria (65-88%), 98% for tetanus (86-100%), 91% (88-94%) for polio type 1, 95% (90-98%) for polio type 2, 82% (76-86%) for polio type 3, 84% (54-100%) for hepatitis A and 27% for hepatitis B (anti-HBs; 8-42%). Our results indicate insufficient protection against certain VPD in some subgroups. For all countries except Eritrea, measles seroprotection was below the 95% threshold required for elimination. Measles seroprevalence was lowest among adults younger than 25 years. In comparison, seroprevalence in the Dutch general population was 96% in 2006/07. The results of this study can help prioritizing vaccination of susceptible subgroups of adult asylum seekers, in general and in outbreak situations.

Quantifying the population effects of vaccination and migration on hepatitis A seroepidemiology in Australia

Since licensure of hepatitis A vaccine in Australia in 1994, infection rates have declined to record lows. Cross-sectional serosurveys conducted over this period meanwhile have shown rising population immunity, particularly in young to middle-aged Australians. In this study, we performed a retrospective birth cohort analysis to estimate the contributions of infection, migration and vaccination towards increased levels of age specific hepatitis A seroprevalence in Australia. When aggregated across age, we find that two-thirds of the increase in population seropositivity (67.04%) between 1994 and 2008 was due to vaccination, just under one-third due to migration, with a negligible contribution from infection (<1%). Comparisons with other data sources reflecting vaccine uptake suggest the magnitude of this effect is realistic. We suggest that these results primarily relate to opportunistic vaccination and indicate the level of population immunity achievable through opportunistic programs providing further evidence for policy considerations around universal hepatitis A vaccine recommendations.

Risk of hepatitis A decreased among Dutch travelers to endemic regions in 2003 to 2011

We divided the number of travel-related hepatitis A cases notified in Dutch surveillance (2003-2011) by travel data obtained from an annual holiday survey to estimate the risk of hepatitis A among Dutch travelers. Of the 2,094 cases notified, 931 (44%) were imported. Morocco (n = 272, 29%), Turkey (n = 98, 11%), and Egypt (n = 87, 9%) accounted for the largest proportion of cases. Attack rates in returnees from high or intermediate endemic regions declined from 7.5 per 100,000 travelers (95% CI 6.7-8.4) in 2003-2005 to 3.5 (95% CI 3.0-4.0) in 2009-2011 (p < 0.01). Despite the decrease in risk, vaccination remains important, and routine risk monitoring should also be considered.

Vaccination in the elderly: what can be recommended?

The age-associated increased susceptibility to infectious disease would suggest that vaccination should be a route to promote healthy aging and keep our seniors autonomous and independent. While vaccination represents a cost-effective and efficient strategy at community level, the ability of the immune system to mount a protective immune response is still unpredictable at the level of the individual. Thus, at a similar age, some individuals, including the elderly, might still be 'good' responders while some other, even younger, would definitely fail to mount a protective response. In this review, the current burden of vaccine-preventable diseases in the aging and aged population will be detailed with the aim to identify the ideal vaccine candidates over the age of 50 years. This article will conclude with potential strategies to reduce, as best as possible, this burden and the imperative need to overcome barriers in extending current vaccine coverage towards to a lifelong vaccine schedule.

Underdiagnosis of foodborne hepatitis A, The Netherlands, 2008-2010(1.)

Outbreaks of foodborne hepatitis A are rarely recognized as such. Detection of these infections is challenging because of the infection’s long incubation period and patients’ recall bias. Nevertheless, the complex food market might lead to reemergence of hepatitis A virus outside of disease-endemic areas. To assess the role of food as a source of infection, we combined routine surveillance with real-time strain sequencing in the Netherlands during 2008–2010. Virus RNA from serum of 248 (59%) of 421 reported case-patients could be sequenced. Without typing, foodborne transmission was suspected for only 4% of reported case-patients. With typing, foodborne transmission increased to being the most probable source of infection for 16%. We recommend routine implementation of an enhanced surveillance system that includes prompt forwarding and typing of hepatitis A virus RNA isolated from serum, standard use of questionnaires, data sharing, and centralized interpretation of data.

[Epidemiology of hepatitis A, B, and C among adults in Germany: results of the German Health Interview and Examination Survey for Adults (DEGS1)]

Ten years after seroepidemiological data were obtained in the German National Health Interview and Examination Survey 1998 (GNHIES98), German Health Interview and Examination Survey (DEGS1) data contribute to a population-based, representative surveillance of hepatitis A and B immunity and of the serological markers for hepatitis C in Germany. The prevalence of antibodies against the hepatitis A virus is 48.6 %. In comparison to the situation 10 years ago, seroprevalence is significantly higher among 18- to 39-year-old adults and is significantly lower in those aged 50-79 years. The association between age and seroprevalence has changed, indicating a decrease in naturally acquired hepatitis A immunity. Individual and population immunity has to be achieved through vaccination. Prevalence of hepatitis B antibodies indicates that 5.1 % of adults have been exposed to the virus, significantly fewer than 10 years ago (7.9 %). Prevalence of hepatitis B surface antibodies indicates that 22.9 % of adults have been vaccinated against hepatitis B. Vaccination coverage has increased in all age groups and is highest in the younger age groups. These positive trends can be attributed to the general recommendation since 1995 to vaccinate against hepatitis B. For hepatitis C, the prevalence of antibodies in the general population is 0.3 %. Germany thus remains a low-HCV-endemic country. An English full-text version of this article is available at SpringerLink as supplemental.

Economic evaluations of hepatitis A vaccination in middle-income countries

Economic evaluations of hepatitis A vaccination are important to assist national and international policy makers in different jurisdictions on making effective decisions. Up to now, a comprehensive review of the potential health and economic benefits on hepatitis A vaccination in middle-income countries (MICs) has not been performed yet. In this study, we reviewed the literature on the cost-effectiveness of hepatitis A vaccination in MICs. Most of the studies confirmed that hepatitis A vaccination was cost effective or even cost saving under certain conditions. We found that vaccine price, medical costs, incidence and discount rate were the most influential parameters on the sensitivity analyses. Vaccine price has been shown as a barrier for MICs in implementing universal vaccination of hepatitis A. Given their relatively limited financial resources, implementation of single-dose vaccination could be considered. Despite our findings, we argue that further economic evaluations in MICs are still required in the near future.

Ηepatitis A and enteric fever in Greece, 2004-2011: a cross-sectional analysis

BACKGROUND

In Greece the number of international travellers has increased significantly the past decade.

AIM

To study the impact of international travels on the epidemiology of hepatitis A and enteric fever in Greece.

METHODS

We studied cases of hepatitis A and enteric fever notified through the National Surveillance System from January 1, 2004 through December 31, 2011.

RESULTS

A total of 921 cases of hepatitis A and 106 cases of enteric fever were notified; of them, 88 (9.5%) and 46 (43.4%) were travel-associated, respectively. Travellers returning from Eastern Europe and the Middle East accounted for most imported cases of hepatitis A (37 (43.5%) and 14 (16.5%) cases, respectively). The Indian subcontinent was the prevalent area of acquisition of travel-associated enteric fever, followed by the Middle East (35 (83.3%) and 4 (9.5%) cases, respectively). Foreign-born travellers accounted for 43 (48.8%) and 39 (86.6%) cases of travel-associated hepatitis A and enteric fever, respectively. Children <15 years accounted for 65.1% of hepatitis A cases and 7.7% among foreign-born travellers. Greek Roma accounted for 270 (29.3%) of all hepatitis A cases notified.

CONCLUSIONS

International travels have a significant impact on the epidemiology of enteric fever in Greece, affecting mainly foreign travellers. Hepatitis A carries a significant burden of morbidity among Greek travellers and children of foreign nationality. There is a need to improve travel medicine services for travellers travelling to developing countries.

Scoping the impact of changes in population age-structure on the future burden of foodborne disease in the Netherlands, 2020-2060

A demographic shift towards a larger proportion of elderly in the Dutch population in the coming decades might change foodborne disease incidence and mortality. In the current study we focused on the age-specific changes in the occurrence of foodborne pathogens by combining age-specific demographic forecasts for 10-year periods between 2020 and 2060 with current age-specific infection probabilities for Campylobacter spp., non-typhoidal Salmonella, hepatitis A virus, acquired Toxoplasma gondii and Listeria monocytogenes. Disease incidence rates for the former three pathogens were estimated to change marginally, because increases and decreases in specific age groups cancelled out over all ages. Estimated incidence of reported cases per 100,000 for 2060 mounted to 12 (Salmonella), 51 (Campylobacter), 1.1 (hepatitis A virus) and 2.1 (Toxoplasma). For L. monocytogenes, incidence increased by 45% from 0.41 per 100,000 in 2011 to 0.60 per 100,000. Estimated mortality rates increased two-fold for Salmonella and Campylobacter to 0.5 and 0.7 per 100,000, and increased by 25% for Listeria from 0.06 to 0.08. This straightforward scoping effort does not suggest major changes in incidence and mortality for these food borne pathogens based on changes in de population age-structure as independent factor. Other factors, such as changes in health care systems, social clustering and food processing and preparation, could not be included in the estimates.

Risk factors for acute hepatitis A infection in Korea in 2007 and 2009: a case-control study

This study aimed to identify the risk factors associated with acute hepatitis A virus (HAV) infection in the Korean population. Participants were recruited from five referral hospitals across the country in 2007 and from 11 hospitals in 2009. Patients with positive anti-HAV IgM antibody tests became the case group, while patients treated for non-contagious diseases at the same hospitals were recruited as controls. A total of 222 and 548 case-control pairs were studied in the 2007 and 2009 surveys, respectively. Data from the surveys were analyzed jointly. In a multivariate analysis, sharing the household with HAV-infected family members (OR, 6.32; 95% CI, 1.4-29.6), contact with other HAV-infected individuals (OR, 4.73; 95% CI, 2.4-9.4), overseas travel in 2007 (OR, 19.93; 95% CI, 2.3-174.4), consumption of raw shellfish (OR, 2.51; 95% CI, 1.8-3.5), drinking bottled water (OR, 1.64; 95% CI, 1.3-8.4), and occupation that involve handling food (OR, 3.30; 95% CI, 1.3-8.4) increased the risk of HAV infection. Avoiding contact with HAV-infected individuals and avoiding raw foods eating could help minimize the risk of hepatitis A infection. Immunization must be beneficial to individuals who handle food ingredients occupationally or travel overseas to HAV-endemic areas.

Sex bias in infectious disease epidemiology: patterns and processes

BACKGROUND

Infectious disease incidence is often male-biased. Two main hypotheses have been proposed to explain this observation. The physiological hypothesis (PH) emphasizes differences in sex hormones and genetic architecture, while the behavioral hypothesis (BH) stresses gender-related differences in exposure. Surprisingly, the population-level predictions of these hypotheses are yet to be thoroughly tested in humans.

METHODS AND FINDINGS

For ten major pathogens, we tested PH and BH predictions about incidence and exposure-prevalence patterns. Compulsory-notification records (Brazil, 2006-2009) were used to estimate age-stratified ♂:♀ incidence rate ratios for the general population and across selected sociological contrasts. Exposure-prevalence odds ratios were derived from 82 published surveys. We estimated summary effect-size measures using random-effects models; our analyses encompass ∼0.5 million cases of disease or exposure. We found that, after puberty, disease incidence is male-biased in cutaneous and visceral leishmaniasis, schistosomiasis, pulmonary tuberculosis, leptospirosis, meningococcal meningitis, and hepatitis A. Severe dengue is female-biased, and no clear pattern is evident for typhoid fever. In leprosy, milder tuberculoid forms are female-biased, whereas more severe lepromatous forms are male-biased. For most diseases, male bias emerges also during infancy, when behavior is unbiased but sex steroid levels transiently rise. Behavioral factors likely modulate male-female differences in some diseases (the leishmaniases, tuberculosis, leptospirosis, or schistosomiasis) and age classes; however, average exposure-prevalence is significantly sex-biased only for Schistosoma and Leptospira.

CONCLUSIONS

Our results closely match some key PH predictions and contradict some crucial BH predictions, suggesting that gender-specific behavior plays an overall secondary role in generating sex bias. Physiological differences, including the crosstalk between sex hormones and immune effectors, thus emerge as the main candidate drivers of gender differences in infectious disease susceptibility.

Effects of an ageing population and the replacement of immune birth cohorts on the burden of hepatitis A in the Netherlands

BACKGROUND

In populations in which the incidence of hepatitis A virus (HAV) infection has declined due to socio-economic improvements, better sanitation and hygiene, and vaccination, birth cohorts who have long-term immunity through exposure early in life are now being replaced by non-immune cohorts, meaning that more cases in the elderly may occur in future. Our goal was to qualitatively investigate the interaction of this cohort effect and demographic change (population ageing) on the estimated disease burden of HAV infection in the Netherlands.

METHODS

We used dynamic MSIR (maternal immunity-susceptible-infectious-recovered) transmission and demographic models to simulate annual HAV incidence over the period 2000-2030, and estimated disease burden using the disability-adjusted life years (DALY) measure and a pre-defined disease progression model. Five scenarios representing different force of infection situations were simulated.

RESULTS

The overall disease burden was projected to decrease over the simulation period in the baseline scenario (310 DALYs in 2000 compared with 67 in 2030). This decreasing trend was absent for the 55+ years age group; 23.5% of all new infections were predicted to occur in the 55+ group in 2030, compared with 5.5% in the 55+ group in 2000.

CONCLUSIONS

In the absence of further public health interventions and under the assumption of a continued steady decline in the force of infection, the HAV disease burden in the Netherlands is predicted to decrease over the coming decades, but with proportionally more of the burden occurring within the increasingly larger segment of the population represented by elderly persons who are no longer naturally immune.

Declining incidence of hepatitis A in Amsterdam (The Netherlands), 1996-2011: second generation migrants still an important risk group for virus importation

BACKGROUND

The Netherlands is a very low endemic country for hepatitis A virus infections (HAV, notification rate of <1/100,000). Historically in Amsterdam, a large proportion of infections are imported from Turkey and Morocco in children returning from summer holiday. Annually since 1998, the public health service of Amsterdam has targeted these children for HAV vaccination before the summer. As the population of non-western immigrants and their descendents increases, we describe recent trends in HAV in ethnic groups in Amsterdam (1996-2011), identifying current risk groups and recommending targeted prevention through vaccination.

METHODS

We studied all cases of (non-homosexually acquired) HAV infection notified in the Amsterdam region (1996-2011, n=819) by ethnic group and generation (first/second generation migrants: FGM and SGM respectively). Incidence rates were estimated as the average number of cases per 100,000/year. Using Poisson regression, we calculated incidence rate ratios (IRR) by ethnic group and generation adjusted for age and calendar year, and modeled seasonal variation using a smoothed time series.

RESULTS

Incidence of HAV in Amsterdam dropped from 24.8/100,000 population in 1996 (178 cases) to 1.0/100,000 in 2011 (8 cases). Since 2005, 56% of cases are imported, the majority (62%) in second generation migrant (SGM) children of Moroccan, or other non-western ethnic backgrounds. The adjusted IRR in SGM relative to the ethnic Dutch population was 3.7 (95% CI: 2.3-6.1) in Moroccan SGM, 4.3 (95%CI: 2.6-7.2) in SGM of other non-western backgrounds and 1.9 (95%CI: 0.8-4.1) in Turkish SGM.

CONCLUSION

Though incidence of HAV in Amsterdam has declined substantially since 1996, it is still higher in SGM children of Moroccan & other non-western ethnic backgrounds. In line with WHO recommendations of June 2012, introduction of single-dose HAV vaccination, targeted at SGM children from HAV endemic countries, could be considered within the routine childhood vaccination schedule.

Changes in seroprevalence to hepatitis A in Victoria, Australia: a comparison of three time points

Serological data provide an important measure of past exposure and immunity to hepatitis A virus (HAV) infection in a population. National serosurveys from developed countries have typically indicated a decline in HAV seroprevalence over time as sanitation levels improve. We examined trends in the seroepidemiology of HAV antibodies in Victoria, Australia, drawing on cross-sectional samples taken at three time points over a 20-year period. Stored sera from 1988 (n=753), 1998 (n=1091), and 2008 (n=791) from persons aged 1-69 years were obtained from the state of Victoria, Australia. The within-year population adjusted results show a significant trend of increasing population HAV seroprevalence over time from 34.3% (95% CI 31.7-36.9) in 1988, to 40.0% (95% CI 37.1-42.8) in 1998 and 55.1% (95% CI 52.1-58.1) in 2008, P<0.0001. A particularly noticeable rise in population seroprevalence was observed between 1998 and 2008 for those aged 5-39 years. The increase in HAV seropositivity over time is in contrast to the declining rates of disease notification in Australia. Based on comparisons with other Australian data, it appears the increase in population seroprevalence over the last two decades is unlikely to be due to endemic transmission of infection. Instead, other factors, including increases in travel to HAV endemic regions, migration to Australia from HAV endemic regions and vaccine uptake are more likely causes. Ongoing monitoring of serological HAV profiles in the population is required to determine future policy direction to prevent increased burden.

Use of PCR for detection of faecal HAV as a screening tool in an outbreak of hepatitis A in daycare centres

Using polymerase chain reaction (PCR) to detect faecal hepatitis A virus (HAV) can be a useful tool for investigating HAV outbreaks, especially in low-endemic countries. We describe the use of faecal HAV PCR as a non-invasive tool for screening. Two Dutch children visiting different daycare centres were diagnosed with hepatitis A in 2011. A systematic contact investigation was started in the daycare centres and relevant contacts were screened. The faecal HAV PCR test was used to screen the children. The employees were screened with a serum IgM. The faecal HAV PCR test proved to be an appropriate tool for screening. The screening of a total of 135 children and employees in the daycare centres resulted in evidence of eight asymptomatic infections and transmission to three related daycare centres. Control measures were taken including immunization. Compared to an epidemiological investigation without screening, 144 extra contacts were vaccinated based on the screening results. This most likely led to improved prevention of expansion of the outbreak.

Seroprevalence of hepatitis E antibodies and risk profile of HEV seropositivity in The Netherlands, 2006–2007

Hepatitis E virus (HEV) is now considered an endemic pathogen in industrialized countries, leading to acute and sometimes chronic hepatitis, mostly in vulnerable people. The endemic sources are unclear. A survey in The Netherlands in 2006–2007 showed a 1·9% seroprevalence of HEV antibodies measured by ELISA and confirmed by immunoblot in a nationwide sample. Overall, in 134/7072 (1·9%) seropositive individuals, older age (P<0·01), being male (P<0·01), working with patients (P=0·03), working with animals (P=0·07), recent diarrhoeal complaints (P=0·07) and adhering to a religion that considers pigs unclean (P<0·01) were independently associated with seropositivity in multivariate analysis. Sub-analysis of 59/4022 (1·5%) anti-HEV antibody-positive subjects with probable endemic exposure showed independent association with youngest household member being aged <5 years or between 19 and <65 years (P=0·05) in multivariate analysis. These findings may contribute to a better understanding of the sources of endemic HEV exposure, and also highlight the need for systematic epidemiological and serological evaluation of new cases.

Trends in knowledge, attitudes, and practices of travel risk groups toward prevention of hepatitis A: results from the Dutch Schiphol Airport survey 2002 to 2009

BACKGROUND

Previous studies investigating the travelers' knowledge, attitudes, and practices (KAP) profile indicated an important educational need among those traveling to risk destinations. Initiatives to improve such education should target all groups of travelers, including business travelers, those visiting friends and relatives (VFR), and older adult travelers.

METHODS

In the years 2002 to 2009, a longitudinal questionnaire-based survey was conducted at the Dutch Schiphol Airport with the aim to study trends in KAP of travel risk groups toward prevention of hepatitis A. The risk groups last-minute travelers, solo travelers, business travelers, travelers VFR, and older adult travelers were specifically studied.

RESULTS

A total of 3,045 respondents were included in the survey. Travelers to destinations with a high risk for hepatitis A had significantly less accurate risk perceptions (knowledge) than travelers to low-to-intermediate-risk destinations. The relative risk for hepatitis A in travelers to high-risk destinations was probably mitigated by less intended risk-seeking behavior and by higher protection rates against hepatitis A as compared with travelers to low-to-intermediate-risk destinations. Logistic regression analyses showed that an age >60 years was the only significant determinant for improvement of their knowledge. Trend analyses showed a significant change over time in attitude toward more risk-avoiding behavior and toward higher protection rates against hepatitis A in travelers to high-risk destinations. The KAP profile of the risk groups travelers VFR (irrespective of hepatitis A risk of their destination) and solo as well as last-minute travelers to high-risk destinations substantially increased their relative risk for hepatitis A.

CONCLUSIONS

The results of this longitudinal survey in Dutch travelers suggest an annual 5% increase in protection rates against hepatitis A coinciding with an annual 1% decrease in intended risk-seeking behavior. This improvement may reflect the continuous efforts of travel health advice providers to create awareness and to propagate safe and healthy travel. The KAP profile of travelers visiting friends and relatives (VFR) and solo as well as last-minute travelers to high-risk destinations substantially increased their relative risk for hepatitis A. These risk groups should be candidates for targeted interventions.