Public Release: 

Italy: Ongoing hepatitis A virus outbreak among men who have sex with men is linked to current outbreaks in Europe

European Association for the Study of the Liver

12 April 2018, Paris, France: Hepatitis A viruses (HAVs) circulating in an ongoing outbreak among men who have sex with men (MSM) in the Lombardy region of Italy are predominantly attributable to strains linked to two other recent outbreaks in Europe, according to a study presented today at The International Liver Congress™ 2018 in Paris, France. The study found that earlier cases in the Lombardy outbreak were related to an HAV strain reported in the Netherlands, while later cases were more frequently linked to a strain seen in the UK.

Although HAV is rarely fatal, 10-15% of symptomatic patients experience an illness lasting several months, and comorbidities increase the chance of serious liver complications.11 HAV is generally transmitted through the faecal/oral route, although sexually transmitted outbreaks of HAV have occurred among MSM.11,12 Genetic sequencing of the HAV circulating in a particular outbreak can help determine its source and potentially help identify at-risk populations.13 Effective vaccines have become available within the last 25 years and routine vaccination is widely recommended.14

'We wanted to understand the ongoing HAV outbreak within a large group of patients including MSM from seven hospitals in the Lombardy region', explained Dr Massimo Iavarone from the Fondazione IRCCS Ca' Granda Maggiore Hospital in Milan, Italy, and lead author of the study. 'We used viral phylogenetic analysis to see if this outbreak was linked to other recent European outbreaks'.

The study prospectively analyzed 244 cases of acute HAV between January and May 2017 (median age 33 years, range 18-76; 94% male; 59% MSM). The incidence rate of HAV in Lombardy was also analyzed and was found to be 9.512 per 100,000 inhabitants during the study period, compared with 1.069 in 2016 and 0.750 in 2015. The phylogenetic correlation between the viruses currently circulating in Lombardy and other HAV strains was assessed by sequencing the VP1/2A region.

Hospitalization was required by 80% of patients (median stay 7 days, range 2-44), and the median (range) alanine aminotransferase and bilirubin peak levels were 2,652 (47-8,914) IU/mL and 6.6 (0.4-18) mg/dL, respectively. Severe liver injury according to the EASL definitions occurred in 14% of patients, with no cases requiring liver transplants.

The molecular phylogenetic analyses revealed that 93% of patients were infected by HAV genotype IA and 7% with genotype IB. All of the genotype IA infections matched strains from one of three European outbreaks (UK, 54%; The Netherlands, 45%; Germany, 1%). Interestingly, the proportion of cases infected by each strain varied with time; the strain from the Netherlands accounted for 100% of the January cases, but the strain from the UK dominated the later months of the outbreak (May 68%, June 70%). 'There is a high hospitalization rate for the patients in these linked HAV outbreaks involving young active workers, which may impact admissions to liver and infectious disease units and have significant direct and indirect economic consequences', said Dr Iavarone. 'Efforts to increase hepatitis A vaccine coverage in high-risk groups must be taken to strengthen population protection from HAV'. 'This study emphasizes the risk of acute HAV infection via sexual transmission in risk groups such as MSM', said Prof. Markus Cornberg from the Hannover Medical School, Germany, and EASL Governing Board Member. 'Awareness campaigns for the prevention of sexually transmitted infections are important, and in this case of HAV, vaccination can prevent infections'.


About The International Liver Congress™

This annual congress is the biggest event in the EASL calendar, attracting scientific and medical experts from around the world to learn about the latest in liver research. Attending specialists present, share, debate and conclude on the latest science and research in hepatology, working to enhance the treatment and management of liver disease in clinical practice. This year, the congress is expected to attract approximately 10,000 delegates from all corners of the globe. The International Liver Congress™ 2018 will take place from 11¬-15 April 2018 at the Paris Convention Centre, Paris, France.

About The European Association for the Study of the Liver (EASL)

Since its foundation in 1966, this not-for-profit organization has grown to over 4,000 members from all over the world, including many of the leading hepatologists in Europe and beyond. EASL is the leading liver association in Europe, having evolved into a major European association with international influence, and with an impressive track record in promoting research in liver disease, supporting wider education and promoting changes in European liver policy.


For more information, please contact the ILC Press Office at:

Onsite location reference

Session title: Viral hepatitis A/E: Clinical aspects
Time, date and location of session: 12. April 2018, 04:30 PM - 04:45 PM
Presenter: Dr Massimo Iavarone, Italy
Abstract: Outbreak of acute hepatitis A involving young men in Lombardy region, Italy: risk factors, clinical and virological characteristics
Author disclosures
None reported in relation to this study.


11. Matheny SC, Kingery JE. Hepatitis A. Am Fam Physician. 2012;86(11):1027-34.
12. Stene-Johansen K, et al. Molecular epidemiological studies show that hepatitis A virus is endemic among active homosexual men in Europe. J Med Virol. 2007;79(4):356-65.
13. Bruni R, et al. Hepatitis A virus genotypes and strains from an endemic area of Europe, Bulgaria 2012-2014. BMC Infect Dis. 2017;17(1):497.
14. Stuurman AL, et al. Impact of universal mass vaccination with monovalent inactivated hepatitis A vaccines - A systematic review. Hum Vaccin Immunother. 2017;13(3):724-36.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.