Improving preparedness to respond to cross-border hepatitis A outbreaks in the European Union/European Economic Area: towards comparable sequencing of hepatitis A virus

Hepatitis A virus infection

Hepatitis A is a vaccine-preventable infection caused by the hepatitis A virus (HAV). Over 150 million new infections of hepatitis A occur annually. HAV causes an acute inflammatory reaction in the liver that usually resolves spontaneously without chronic sequelae. However, up to 20% of patients experience a prolonged or relapsed course and <1% experience acute liver failure. Host factors, such as immunological status, age, pregnancy and underlying hepatic diseases, can affect the severity of disease. Anti-HAV IgG antibodies produced in response to HAV infection persist for life and protect against re-infection; vaccine-induced antibodies against hepatitis A confer long-term protection. The WHO recommends vaccination for individuals at higher risk of infection and/or severe disease in countries with very low and low hepatitis A virus endemicity, and universal childhood vaccination in intermediate endemicity countries. To date, >25 countries worldwide have implemented such programmes, resulting in a reduction in the incidence of HAV infection. Improving hygiene and sanitation, rapid identification of outbreaks and fast and accurate intervention in outbreak control are essential to reducing HAV transmission.

Seroprevalence and genotype distribution of hepatitis A virus in the pre-vaccine era in South Transdanubia, Hungary (2010-2020)

In this study, the age-related seroprevalence of hepatitis A virus (HAV) infection was investigated in the population in South-Transdanubia, Southwest Hungary (Central Europe) between years 2010 and 2020. Up to the age of 40, the HAV seropositivity was less than 18% in all age groups indicating a low level of HAV endemicity in this part of the country in the covered study period. The HAV seropositivity started to increase at the age group 41-45 years, reaching the ∼50% at age group 56-60, and 75-80% at age group 66-70, respectively. A total of 43 (0.2%) of the 21,106 tested sera were HAV IgM-positive (the annual percentage range of HAV IgM-positivity was 0.046-0.6%). Total of 24 (55.8%) of the 43 HAV IgM-positive samples tested RT-PCR-positive confirmed as HAV sub-genotypes IA (N = 17; 70.8%) and IB (N = 7; 29.2%), respectively. Imported HAV infections (three cases from Romania, and one-one case from Austria and Italy), two small outbreaks and 11 cases of a genetically identical sub-genotype IA strain (GenBank number of the prototype strain: KM657825) from 2012 to 2014 were identified later connected directly to the enormous HAV outbreak initiated among men who have sex with men (MSM) at the end of 2011 in the capital Budapest. In summary, low endemicity but high and increased susceptibility for HAV infection was found in the population in Southwest Hungary, where repeated introduction of sub-genotypes IA and IB HAV strains were identified between 2010 and 2020.

The European Union One Health 2020 Zoonoses Report

This report of the EFSA and the European Centre for Disease Prevention and Control presents the results of zoonoses monitoring activities carried out in 2020 in 27 EU Member States (MS) and nine non-MS. Key statistics on zoonoses and zoonotic agents in humans, food, animals and feed are provided and interpreted historically. Two events impacted 2020 MS data collection and related statistics: the Coronavirus Disease 2019 (COVID-19) pandemic and the withdrawal of the United Kingdom from the EU. In 2020, the first and second most reported zoonoses in humans were campylobacteriosis and salmonellosis, respectively. The EU trend for confirmed human cases of these two diseases was stable (flat) from 2016 to 2020. Fourteen of the 26 MS reporting data on Salmonella control programmes in poultry met the reduction targets for all poultry categories. Salmonella results for carcases of various species performed by competent authorities were more frequently positive than own-checks conducted by food business operators. This was also the case for Campylobacter quantification results from broiler carcases for the MS group that submitted data from both samplers, whereas overall at EU level, those percentages were comparable. Yersiniosis was the third most reported zoonosis in humans, with 10-fold less cases reported than salmonellosis, followed by Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes infections. Illnesses caused by L. monocytogenes and West Nile virus infections were the most severe zoonotic diseases with the highest case fatality. In 2020, 27 MS reported 3,086 foodborne outbreaks (a 47.0% decrease from 2019) and 20,017 human cases (a 61.3% decrease). Salmonella remained the most frequently reported causative agent for foodborne outbreaks. Salmonella in 'eggs and egg products', norovirus in 'crustaceans, shellfish, molluscs and products containing them' and L. monocytogenes in 'fish and fish products' were the agent/food pairs of most concern. This report also provides updates on tuberculosis due to Mycobacterium bovis or Mycobacterium caprae, Brucella, Trichinella, Echinococcus, Toxoplasma, rabies, Coxiella burnetii (Q fever) and tularaemia.

Viral hepatitis update: Progress and perspectives

Viral hepatitis, secondary to infection with hepatitis A, B, C, D, and E viruses, are a major public health problem and an important cause of morbidity and mortality. Despite the huge medical advances achieved in recent years, there are still points of conflict concerning the pathogenesis, immune response, development of new and more effective vaccines, therapies, and treatment. This review focuses on the most important research topics that deal with issues that are currently being solved, those that remain to be solved, and future research directions. For hepatitis A virus we will address epidemiology, molecular surveillance, new susceptible populations as well as environmental and food detections. In the case of hepatitis B virus, we will discuss host factors related to disease, diagnosis, therapy, and vaccine improvement. On hepatitis C virus, we will focus on pathogenesis, immune response, direct action antivirals treatment in the context of solid organ transplantation, issues related to hepatocellular carcinoma development, direct action antivirals resistance due to selection of resistance-associated variants, and vaccination. Regarding hepatitis D virus, we describe diagnostic methodology, pathogenesis, and therapy. Finally, for hepatitis E virus, we will address epidemiology (including new emerging species), diagnosis, clinical aspects, treatment, the development of a vaccine, and environmental surveillance.

Hepatitis A vaccination and its immunological and epidemiological long-term effects - a review of the evidence

Hepatitis A virus (HAV) infections continue to represent a significant disease burden causing approximately 200 million infections, 30 million symptomatic illnesses and 30,000 deaths each year. Effective and safe hepatitis A vaccines have been available since the early 1990s. Initially developed for individual prophylaxis, HAV vaccines are now increasingly used to control hepatitis A in endemic areas. The human enteral HAV is eradicable in principle, however, HAV eradication is currently not being pursued. Inactivated HAV vaccines are safe and, after two doses, elicit seroprotection in healthy children, adolescents, and young adults for an estimated 30-40 years, if not lifelong, with no need for a later second booster. The long-term effects of the single-dose live-attenuated HAV vaccines are less well documented but available data suggest they are safe and provide long-lasting immunity and protection. A universal mass vaccination strategy (UMV) based on two doses of inactivated vaccine is commonly implemented in endemic countries and eliminates clinical hepatitis A disease in toddlers within a few years. Consequently, older age groups also benefit due to the herd protection effects. Single-dose UMV programs have shown promising outcomes but need to be monitored for many more years in order to document an effective immune memory persistence. In non-endemic countries, prevention efforts need to focus on 'new' risk groups, such as men having sex with men, prisoners, the homeless, and families visiting friends and relatives in endemic countries. This narrative review presents the current evidence regarding the immunological and epidemiological long-term effects of the hepatitis A vaccination and finally discusses emerging issues and areas for research.

High impact of molecular surveillance on hepatitis A outbreak case detection in Sweden: a retrospective study, 2009 to 2018

BackgroundSwedish hepatitis A surveillance includes sequence-based typing, but its contribution to outbreak detection in relation to epidemiological investigations has not been fully evaluated.AimTo evaluate the role of sequence-based typing in hepatitis A outbreak detection and to describe the hepatitis A epidemiology in Sweden to improve surveillance.MethodsWe retrospectively investigated hepatitis A virus sequences of 447 cases notified in Sweden 2009-18. We performed a phylogenetic analysis of evolutionary distances to identify cases with similar virus sequences (≥ 459/460 identical nt in the VP1/P2A junction). Unique sequences, dyads and sequence-based clusters (SBCs) were identified. We linked non-sequenced cases by epidemiological information and retrospectively assessed the value of typing for outbreak identification.ResultsFifty-five percent (n = 542/990) of the notified hepatitis A cases were referred to the Public Health Agency of Sweden for typing and 447 (45%) were sequenced successfully. Subgenotypes included IA (42.5%, n = 190), IB (42.7%, n = 191) and IIIA (14.8%, n = 66). Phylogenetic analysis identified 154 unique sequences, 33 dyads (66 cases) and 34 SBCs (227 cases). The combination of molecular and epidemiological data revealed 23 potential outbreaks comprising 201 cases. Cases were linked by sequence (59%, n = 118), epidemiological data (11%, n = 23) or both (30%, n = 60). Typing was needed to identify 15 of 23 potential outbreak signals.ConclusionSequence-based typing contributed substantially to detecting clustering cases and identifying outbreaks in Sweden. The results show routine sequence-based typing detects outbreaks, promotes timely outbreak investigations and facilitates international collaboration.

Lessons from intensified surveillance of viral hepatitis A, Israel, 2017 and 2018

Introduction

Universal vaccination of toddlers has led to very low hepatitis A (HAV) endemicity in Israel. However, sporadic outbreaks still occur, necessitating better surveillance.

Aim

To implement a comprehensive HAV surveillance programme.

Methods

In 2017 and 2018, sera from suspected HAV cases that tested positive for anti-HAV IgM antibodies were transferred to the Central Virology Laboratory (CVL) for molecular confirmation and genotyping. Sewage samples were collected in Israel and Palestine* and were molecularly analysed. All molecular (CVL), epidemiological (District Health Offices and Epidemiological Division) and clinical (treating physicians) data were combined and concordantly assessed.

Results

Overall, 146 cases (78 in 2017 and 68 in 2018, median age 34 years, 102 male) and 240 sewage samples were studied. Most cases (96%) were unvaccinated. In 2017, 89% of cases were male, 45% of whom were men who have sex with men (MSM). In 2018, 49% were male, but only 3% of them were MSM (p < 0.01). In 2017, 82% of cases and 63% of sewage samples were genotype 1A, phylogenetically associated with a global MSM-HAV outbreak. In 2018, 80% of cases and 71% of sewage samples were genotype 1B, related to the endemic strain previously identified in Israel and Palestine*. Environmental analysis revealed clustering of sewage and cases’ sequences, and country-wide circulation of HAV.

Conclusions

Molecular confirmation of HAV infection in cases and analysis of environmental samples, combined with clinical and epidemiological investigation, may improve HAV surveillance. Sequence-based typing of both clinical and sewage-derived samples could assist in understanding viral circulation.