United States epidemiology of hepatitis A: influenced by immigrants visiting friends and relatives in Mexico?

Hepatitis A virus infections, immunisations and demographic determinants in children and adolescents, Germany

Hepatitis A is a vaccine-preventable disease with a global distribution. It predominantly occurs in regions with inadequate living conditions, but also affects populations in industrialised countries. Children are frequently involved in the transmission of hepatitis A virus (HAV) and thus play a central role in the epidemiology of hepatitis A. Here, we investigated HAV infections, immunisations, and associated demographic determinants in a nationwide, population-based, cross-sectional survey conducted in Germany from 2003-2006. Out of 17,640 children and adolescents, complete data sets (HAV serology, demographic information and vaccination card) were available for 12,249 (69%), all aged 3-17 years. We found protective antibody levels (>=20 IU/L) in 1,755 (14%) individuals, 1,395 (11%) were vaccinated against hepatitis A, 360 (3%) individuals were HAV seropositive without prior hepatitis A vaccination, thus indicating a previous HAV infection. Antibody prevalence (attributable to vaccination or infection) increased significantly with age. Multivariate logistic regression revealed that predominantly children and adolescents with migration background-even if they were born in Germany-are affected by HAV infections. Our results provide a rationale to emphasise existing vaccination recommendations and, moreover, to consider additional groups with a higher risk of infection for targeted vaccination, especially children with a migration background.

The role of ethnicity and travel on Hepatitis A vaccination coverage and disease incidence in Arizona at the United States-Mexico Border

BACKGROUND

Hepatitis A (HAV) incidence has decreased in the United States, yet regional disparities persist. The role of international travel has become increasingly important in HAV transmission. We compared the relative burden of HAV in border and non-border regions in Arizona and examined the role of travel in sustaining HAV transmission.

METHODS

HAV vaccination coverage was calculated by age and region, using Arizona State Immunization Information System data. Incidence, demographics, and risk factors of cases reported through Arizona's infectious disease surveillance system between 2006 and 2011 were analyzed.

RESULTS

Hepatitis A incidence was higher in the border region of Arizona. Compared with the rest of Arizona, one-dose coverage in children<15 years was lower in the border region until 2008. Second dose coverage was lower in the border region, particularly among Spanish speakers. International travel among cases was generally high; however, in the border region cases were more likely to visit Mexico or South/Central America (94% vs. 80%, P value = 0.01) and be Hispanic (68% vs. 42%, P value = 0.0003).

CONCLUSIONS

Rates of HAV continue to be higher in the Arizona border region; the risk appears particularly high among Hispanics with recent travel in the Americas. Border surveillance should be emphasized, along with vaccination of all travelers, to continue to decrease and control HAV.

Acute viral hepatitis in the United States-Mexico border region: data from the Border Infectious Disease Surveillance (BIDS) Project, 2000-2009

Little is known about the characteristics of acute viral hepatitis cases in the United States (US)-Mexico border region. We analyzed characteristics of acute viral hepatitis cases collected from the Border Infectious Disease Surveillance Project from January 2000-December 2009. Over the study period, 1,437 acute hepatitis A, 311 acute hepatitis B, and 362 acute hepatitis C cases were reported from 5 Mexico and 2 US sites. Mexican hepatitis A cases most frequently reported close personal contact with a known case, whereas, US cases most often reported cross-border travel. Injection drug use was common among Mexican and US acute hepatitis B and C cases. Cross-border travel during the incubation period was common among acute viral hepatitis cases in both countries. Assiduous adherence to vaccination and prevention guidelines in the US is needed and strategic implementation of hepatitis vaccination and prevention programs south of the border should be considered.

The changing epidemiology of hepatitis A in Arizona following intensive immunization programs (1988-2007)

INTRODUCTION

Arizona had the highest hepatitis A incidence of any U.S. state during 1987-1997. In 1995, the first hepatitis A vaccines became available in the U.S. A series of hepatitis A vaccination policies and recommendations were implemented in 1996-2006. Our objective was to examine the shifting epidemiologic patterns in hepatitis A in Arizona from 1988 to 2007.

METHODS

Passive surveillance reports to the Arizona Department of Health Services were used to compare hepatitis A rates by age, race/ethnicity and geographic area, before and after widespread vaccination. Reported risk factors and possible sources of infection were compared for two time periods. Age-adjusted incidence during three periods was mapped.

RESULTS

Overall hepatitis A incidence in Arizona fell from 58 cases per 100,000 in 1988 to 2 per 100,000 in 2007. The proportion of reported cases among children dropped from 62% in 1994-1995 to 32% in 2006-2007. Racial/ethnic disparities between American Indians and non-Hispanic White populations have been eliminated. The geographic distribution of cases within the state has shifted. Earlier cases were likely to report contact with another hepatitis A case or childcare facilities, while later cases indicated recent international travel.

CONCLUSION

A major shift in the overall burden of hepatitis A and hepatitis A transmission has occurred in Arizona since the widespread implementation of immunization policies and the concomitant rise in vaccination rates in the state. Current transmission has shifted to older age groups and disparities by race/ethnicity are now highest in Hispanic populations. Future strategies to further reduce hepatitis A transmission may require broadening recommendations to include general adult populations without previous vaccination history.

Determinants of anti-hepatitis A antibody seroprevalence in 2- to 19-year-olds in the USA using NHANES 2007–2008

The aim of the study was to describe the epidemiology and determinants of anti-hepatitis A seroprevalence in 2- to 19-year-olds in the USA for 2007–2008. This study was conducted in a sample of 2621 individuals aged 2–19 years in the USA using data from National Health and Nutrition Examination Survey (NHANES) 2007–2008. The overall seroprevalence of anti- hepatitis A virus (HAV) in this population was 39% (95% confidence interval 32·6–45·3). HAV seroprevalence was higher in Mexican Americans than other ethnic groups, in younger persons, and in those who reported previous vaccination compared to those who did not. We concluded that anti-hepatitis A seroprevalence rates are increasing in younger individuals in the USA, indicating a shift of seroprevalence over time due to vaccination status. Findings are consistent with a persistent influx of infection through international travel and migration and highlight the need to discern hepatitis A infection from vaccination status when assessing the effectiveness of vaccination using seroprevalence data.

Seroprevalence of hepatitis A virus antibodies in the U.S.: results from the National Health and Nutrition Examination Survey

OBJECTIVES

We described seroprevalence of antibody to hepatitis A virus (anti-HAV) in the United States during 1999-2006 and compared it with seroprevalence before the availability of vaccine.

METHODS

We analyzed data from the 1988-1994 and 1999-2006 National Health and Nutrition Examination Survey (NHANES) to obtain estimates of anti-HAV seroprevalence for the U.S. household population. We grouped region of residence based on the 1999 Advisory Committee on Immunization Practices recommendations into 17 states with any recommendation (vaccinating) and 33 states without any recommendation (non-vaccinating).

RESULTS

During 1999-2006, the overall seroprevalence of anti-HAV was 34.9% (95% confidence interval [CI] 33.1, 36.7). During 1999-2006, U.S.-born children living in vaccinating states (33.8%, 95% CI 26.2, 42.2) had a higher seroprevalence than children in non-vaccinating states (11.0%, 95% CI 9.4, 12.8; p < 0.001). Seroprevalence among children increased from 8.0% (95% CI 6.3, 10.1) during 1988-1994 to 20.2% (95% CI 16.0, 24.8) during 1999-2006 (p < 0.001). For U.S.-born children aged 6-19 years, the strongest factor associated with seroprevalence was residence in vaccinating states. Among U.S.-born adults aged > 19 years, the overall age-adjusted seroprevalence of anti-HAV was 29.9% (95% CI 28.3, 31.5) during 1999-2006, which was not significantly different from the seroprevalence during 1988-1994 (32.2%, 95% CI 30.1, 34.4).

CONCLUSIONS

Increases in seroprevalence among children in vaccinating states suggest a positive effect of the 1999 vaccination recommendations.

Role of immigrants and migrants in emerging infectious diseases

Population migration plays a critical role in the spread of disease by initiating outbreaks of acute diseases, changing the prevalence of infectious diseases at a given location, and changing the face of chronic disease resulting from previous infection. This article focuses on the recent demographic changes in North America that have facilitated the introduction and spread of new microbial threats, the role migrant populations play in changing the demographics of specific infectious diseases, and the potential responses of clinicians and public health officials in addressing the challenges posed by these infections. The emphasis of the article is on immigrant and migrant populations entering North America; the role of travelers in emerging infectious diseases is addressed in another article in this issue.

Universal hepatitis A vaccination in the United States: a call for action

Previous hepatitis A recommendations for the United States targeted vaccination of at-risk individuals and children living in states and communities with consistently elevated rates of hepatitis A. Recommendations now call for routine hepatitis A vaccination of all children in the United States beginning at age 1 year (12-23 months). Currently, vaccination coverage rates for hepatitis A remain below rates of other routine childhood vaccines. Achieving a national immunization rate greater than 90% for the recommended 2 doses of hepatitis A vaccine would lessen disease impact throughout society. Routine childhood immunization against hepatitis A can be a highly effective strategy to reduce infection in children and community transmission of the virus, and the elimination of indigenous transmission of hepatitis A is an attainable goal.

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.