Three simultaneous multi-country Hepatitis A outbreaks had no direct link
All outbreaks were caused by a different persistent source of exposure: two were associated with eating berries, while strawberries were suspected in the third outbreak.
Factors influencing the event included increased number of susceptible Europeans, the limited coverage of HAV vaccination, the global trade of potentially contaminated products introduced in the EU/EEA, and the ‘awareness chain effect’ leading to a wave of notifications.
Three outbreaks of HAV infection reported to the Epidemic Intelligence Information System for Food- and Water-borne diseases (EPIS-FWD) of the European Centre for Disease Prevention and Control (ECDC) between March and May 2013 involved over 400 cases from 15 EU/EEA countries and Switzerland.
Outbreak reporting
The first outbreak was initially reported by Denmark on 1 March, with cases subsequently reported by Finland, Norway and Sweden.
As of 6 August, 106 cases had been reported by the four Nordic countries of Denmark, Sweden, Norway and Finland.
Epidemiological investigations, including case interviews and case control study, and purchase history investigations pointed towards frozen strawberries from Egypt and Morocco as the most likely source of infection.
The second outbreak was notified by Norway on 17 April and an additional 13 countries reported associated cases.
As of 20 August, 107 travellers returning from different locations in the Red Sea region, Egypt, were reported infected.
Multi-country epidemiological investigations suggested that the implicated vehicle of infection was a food item distributed to different hotels in Egypt, with strawberries suspected among other fruits.
The third outbreak, reported on 8 May on EPIS-FWD, was thought to have affected about 200 Italian residents as of August 2013, although it was initially reported by Germany following identification of nine HAV infections in travellers returning from northern Italy.
Case interviews and a case control study in Italy, including Dutch and Polish cases, identified imported frozen mixed berries as the vehicle of infection.
Awareness chain effect
The first outbreak in the Nordic countries may have indirectly encouraged Norway to increase sequencing of HAV isolates from reported cases and to detect and report the second outbreak through EPIS-FWD. Just as the two outbreaks may have helped detection in the third outbreak.
To prevent recurrence of similar HAV outbreaks, the risk posed by berries needs to be studied further, said the report.
They added that laboratory capacity and surveillance of viral infections in the EU/EEA should be strengthened.
ECDC’s food- and waterborne toolbox for outbreak investigation could also be developed to include the necessary protocols for HAV detection and sequencing.
Source: Eurosurveillance, Volume 19, Issue 43, 30 October 2014
“Three simultaneous, foodborne, multi-country outbreaks of Hepatitis A virus infection reported in EPIS-FWD in 2013: What does it mean for the European Union?”
Authors: C M Gossner and E Severi
