Outbreak of Hepatitis A virus infection in residents and travellers to Italy

Abstract

Since 1 January 2013, 15 laboratory-confirmed cases of HAV infection have been reported in Germany, the Netherlands and Poland. All cases had travelled to the autonomous provinces of Trento and Bolzano in northern Italy during the exposure period. During the same period, Italy experienced an increase in cases of HAV infection both in the province of Trento and at national level. As the cases do not have a travel history outside the EU within their period of potential exposure, this strongly suggests an outbreak involving several EU Member States, with exposure currently occurring in one EU Member State. The descriptive epidemiology points at a continuous common source of infection. Preliminary epidemiological and environmental investigations indicate mixed frozen berries as the most likely vehicle of infection for this outbreak. A large number of cases reported consumption of berries prior to disease onset. In addition, HAV was isolated from a pack of mixed frozen berries at the residence of one case. RNA sequencing and interviews of patients should provide further evidence to confirm the hypothesis of mixed frozen berries as the vehicle of infection. Viral sequences information on human and food viral specimens are expected from Italy, and on human viral specimens from Poland. Italy is currently developing a multi-state case-control study. According to the available information, it is likely that additional cases will be identified and reported. ECDC invites Member States to raise awareness of a possible increase in HAV cases with a travel history to northern Italy, to report all new cases in EPIS-FWD, to use the common epidemic case definition and questionnaire to interview recent cases and to sequence a subset of viral specimens in order to confirm the link with the current outbreak in northern Italy. Travellers to areas reporting HAV outbreaks should be reminded of the availability of vaccination to prevent the risk of HAV transmission while travelling. Member States, in accordance with their national guidelines, may consider active or passive immunisation of close contacts to cases in order to avoid secondary transmission. ECDC, EFSA and the European Commission, in cooperation with the affected countries, will continue to closely monitor this event and will update the risk assessment as soon as new, relevant information becomes available. Another two HAV-related outbreaks are simultaneously under investigation in four Nordic countries and in travellers returning from Egypt. At present, there is no evidence of links between these outbreaks.