Since March 2017, 30 outbreak cases had information available on travel during the incubation period. Eight of these were infected abroad: five in Portugal, one in Poland, one in Hungary and one either in the United Kingdom or in Portugal. Outbreak cases were also reported in travellers to Hungary and Poland in the preceding weeks. However, confirmed cases with a travel history to Portugal have only been reported since mid-April 2017. It is therefore plausible that Portugal, which has not reported outbreak cases so far, has only recently been affected by this outbreak.

Assessment

Evidence from epidemiological, microbiological, environmental and tracing investigations identified eggs originating from Poland as the vehicle of infections in this outbreak. The current re-emergence of cases infected with the outbreak strains, mostly occurring in the United Kingdom, raises the possibility that a vehicle contaminated with a persistent, still unidentified source remains in circulation.

Actions

Further investigations are required to identify the origin of the transmission resulting in these new cases and to control this outbreak. ECDC continues to monitor the human cases associated with this event and supports sequencing services for countries reporting probable cases with isolates linked to MLVA profile 2-9-7-3-2 or 2-9-7-3-2. EU/EEA countries should consider interviewing new outbreak cases.