Hepatitis A outbreak predominantly affecting men who have sex with men in Northern Ireland, October 2008 to July 2009

O Sfetcu,C Mccaughey,S L Ngui,N Irvine,P Donaghy,C Emerson

doi:10.2807/ese.16.09.19808-en

Abstract

We describe an outbreak of hepatitis A which evolved in Northern Ireland between October 2008 and July 2009, against a background of large concurrent hepatitis A outbreaks in various parts of Europe. Thirty-eight cases were defined as outbreak cases using a stratified case definition; 36 were males with a median age of 29 years and of the 28 males whose sexual orientation was known, 26 were men who have sex with men(MSM). Detailed descriptive epidemiology data collected through standardised questionnaires, together with sequencing of a 289 bp fragment of the VP1/2PA region of the virus, significantly aided the understanding of the spread of the outbreak when non-MSM cases occurred. The sequence of the outbreak strain, genotype IA, was indistinguishable from that involved in a large outbreak in the Czech Republic. Although seeded in a generally susceptible Northern Ireland population, the outbreak remained mostly contained in MSM, showing this sub-population to be the most vulnerable despite ongoing hepatitis A vaccination programmes in genito-urinary medicine clinics.

Highlights

Hepatitis A is an acute, usually self-limiting disease caused by infection with the hepatitis A virus (HAV) [1]
An outbreak case was defined as any resident of Northern Ireland who tested positive for antiHAV IgM after 1 October 2008
Information on the outbreak and details on hepatitis A clinical presentation and prevention were posted on their web-site. This is the first outbreak of hepatitis A in Northern Ireland following a decade of low incidence. It occurred against a background of large concurrent European outbreaks all reported to have started in at-risk groups followed by spread into the general population (Figure 3) [2,3,4,10,12,13]

Summary

Introduction

Hepatitis A is an acute, usually self-limiting disease caused by infection with the hepatitis A virus (HAV) [1]. Asymptomatic and mild disease is common in children but the majority of adults who become infected are symptomatic, often with acute jaundice [5]. With increasing hygiene in developed countries, hepatitis A infection has become much less common leading to populations with a large majority of people who are not immune. One consequence of this is that proportionately more susceptible adults are infected when outbreaks do occur, and more severe clinical symptoms are seen [6]. HAV RNA is a marker of acute infection and is present in the patient’s serum prior to the appearance of anti-HAV IgM [7]. In regions with a low incidence of HAV infection, sequencing of HAV RNA can be used to link apparently sporadic cases and outbreaks [8]

Methods

Results

Discussion

Conclusion