Factors associated to duration of hepatitis a outbreaks: implications for control

Changes in the epidemiology of hepatitis A: Clinical and preventive implications

INTRODUCTION AND OBJECTIVES

Hepatitis A Virus Infection (HAI) has been related to the hygienic-sanitary situation of an area, the changes in the epidemiology of HAI in the province of Guadalajara between 1991 and 2017 are analyzed.

MATERIALS AND METHODS

Cases of HAI declared between 1991 and 2017 in Guadalajara were included. The variables analyzed were age, sex, environment, risk factors for HAI and need for hospitalization. The incidence was compared in three periods: 1991-1999, 2000-2008 and 2009-2017.

RESULTS

Two hundred and thirty-three cases of HAI were declared, the average incidence rate was 4.27 cases/100,000 inhabitants, highest between 1991 and 1999 (6.93) and lowest between 2009 and 2017 (1.92), with an increment in 2017 (5.5). The median age was 16 years (IR: 8.5-28.5 years), 58.4% were male, and the highest incidence occurred between 5 and 14 years in both sexes. The most frequent risk factors were family and non-family contact and trips to endemic areas (18.6%, 17.3% and 18.2%, respectively). The last risk factor increased after 2000 (P=.001), as did the incidence in urban areas. The MSM group showed an increase in the last period (P<.001). Hospital admissions increased progressively from the first to the third period studied (P=.001).

CONCLUSIONS

HAI has a low incidence in our area. More cases related to travel or sexual practices are observed. This should be considered when establishing prevention policies, including vaccination of the most exposed people.

Vaccination strategies for control of community outbreaks of hepatitis A: A comparison of two outbreaks in England

In August 2015 two community outbreaks of hepatitis A virus (HAV) occurred in sub-urban communities in Northern England. Each was managed by an independent outbreak control team. In outbreak one, mass vaccination was deployed targeting a residential area and two schools, while in outbreak two, vaccination was reserved for household-type contacts of cases. The highest vaccination uptake was achieved in the school settings (82% and 95%). These case studies illustrate the range of approaches that can be used and the factors that influence decision-making in response to a hepatitis A community outbreak. Both outbreaks likely started from importation(s) of HAV by returning travellers and spread through extended social networks and the local community. Vaccination strategies were selected based on hypotheses about transmission pathways, which were informed by evidence from oral fluid (OF) testing of asymptomatic contacts. More evidence about the effectiveness of mass vaccination in community outbreaks of hepatitis A in low endemicity settings is needed. Hepatitis A guidelines should include recommendations for the use of mass vaccination and OF testing in outbreaks.

A retrospective pooled analysis assessing the effect of age on the immunogenicity of Havrix™ in healthy adults

Over recent decades, the global incidence of hepatitis A virus infection has been reduced by improvements in sanitation infrastructure and through immunization programs. The immunogenicity and field efficacy of the inactivated hepatitis A vaccine (Havrix™, GSK, Belgium) has been demonstrated in clinical trials, population-impact studies as well as in several outbreak settings. However, immunological data in older populations are limited, with only few studies assessing the immune response of this vaccine in adults aged ≥40 years. This retrospective pooled analysis of 4 2-dose primary vaccination studies compared the immunogenicity and safety of the inactivated hepatitis A vaccine in adults aged ≥40 years with subjects aged 20–30 years (control group; N = 80 in each group). Fifteen days after the first vaccine dose, 79.7% (95% CI: 68.8–88.2) and 92.3% (95% CI: 84.0–97.1) of subjects were seropositive in the ≥40 years and control groups, respectively; 97.5% (95% CI: 91.2–99.7) and 97.4% (95% CI: 91.0–99.7), respectively, were seropositive one month after the first dose. All subjects in both groups (95% CIs: 95.4–100 and 95.3–100, respectively) were seropositive one month after the second dose. Safety profiles were similar in both groups. In conclusion, the inactivated hepatitis A vaccine induced similar immune responses in adults aged ≥40 and 20–30 years one month after the first and second dose whereas younger subjects may demonstrate a higher seroconversion rate 15 days after the first dose.

The important role of early diagnosis and preventive management during a large-scale outbreak of hepatitis A in Thailand

INTRODUCTION

Acute hepatitis A is a worldwide public health problem especially in developing countries. Recently, a large, community-wide outbreak of hepatitis A occurred in the northeast part of Thailand.

METHODS

Demographic and clinical data as well as blood samples were collected and analyzed from patients with acute hepatitis who attended the Buengkan Provincial Hospital from June to September 2012. About 1619 patients with clinical symptoms of hepatitis A visited the hospital during the outbreak which manifested in three waves. Blood samples were collected from 205 patients.

RESULTS

One hundred and seventy eight patients had hepatitis A confirmed by the presence of anti-hepatitis A virus (HAV) IgM and/or HAV-RNA. The sensitivities for anti-HAV IgM and HAV-RNA were 95·5% (170/178) and 61·8% (110/178), respectively. When HAV-RNA was combined with anti-HAV IgM test, this increased the diagnostic yield by 7·2% (8/111) in the early phase of the acute infection (less than 5 days). Investigation of the molecular structure of the detected viruses indicated that all of the infections were caused by HAV genotype IA. There were no fatalities from this outbreak. Rapid detection, health education, sanitation campaigns, and vaccination offered on a voluntary basis have steadily reduced the number of infected patients and stopped the outbreak.

CONCLUSION

Occasionally a large-scale outbreak of HAV genotype IA can occur. A combination of HAV-RNA and anti-HAV IgM tests can increase the diagnostic yield during the early phase of the acute infection. Early diagnosis and preventive management campaigns can slow down and stop the outbreak.

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.

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.