Eurosurveillance - Volume 14, Issue 24, 18 June 2009

In May 2009, the Norwegian Institute of Public Health (NIPH) identified a possible outbreak of Shigella sonnei infection involving four cases. Additionally, five suspected cases in two separate households were reported. Inspectors from the Norwegian Food Safety Authority (NFSA) visited the two households and found an unopened package of sugar peas imported from Kenya in one of the households. One sample from the sugar peas was positive for Shigella sonnei by two PCR methods. Based on this result and information from patient interviews, the NFSA prohibited all sales of sugar peas imported from Kenya.

We report on an outbreak of Shigella sonnei infections involving ten cases notified through the laboratory surveillance system in Denmark in April and May. The likely source was consumption of fresh, raw sugar peas (sugar snaps) imported from Africa. This conclusion was based on interviews with cases and on the occurrence of a similar outbreak one month later in Norway. Fresh imported produce may occasionally be contaminated with pathogenic bacteria even when sold as ready-to-eat.

In this report we describe the findings of laboratory-based surveillance of human cases of influenza A(H1N1)v virus infection in Italy, following the recent worldwide detection of this new virus among human population and the decision of the World Health Organization (WHO) to raise the level of pandemic alert.

Between 9 May and 4 June 2009, a total of 401 laboratory-confirmed cases of influenza A(H1N1)v virus were reported in Japan, from 16 of the 47 Japanese prefectures. The two areas most affected were Osaka prefecture and Kobe city where outbreaks in high schools occurred leading to school closures. To date all cases have had symptoms consistent with seasonal influenza and no severe or fatal cases have been reported.

Concerns about an imminent influenza pandemic have been intensified after the emergence of the new influenza A(H1N1)v strain. Mathematical modeling was employed on recent epidemiological data from Mexico in order to assess the impact of intervention strategies on the spread of influenza A(H1N1)v in the setting of the European region. When initiating the intervention of 100% school closure in a community of 2,000 people at a threshold of 1% cumulative attack rate, the total number of symptomatic cases is predicted to decrease by 89.3%, as compared to the non-intervention scenario. When this measure is coupled with treatment and home isolation of symptomatic cases as well as a 50% reduction of social contacts, a 94.8% decline in the cumulative attack rate is predicted along with a much shorter duration of influenza A(H1N1)v transmission. Active surveillance that will ensure timely treatment and home isolation of symptomatic cases in combination with school closure seem to form an efficient strategy to control the spread of influenza A(H1N1)v.

Clinical specimens from 79 symptomatic individuals with a recent history of travel to countries with verified transmission of influenza A(H1N1)v (North America) were tested with a multiple real-time PCR targeting a broad range of agents that may cause acute respiratory infection. This analysis revealed that besides four cases of influenza A(H1N1)v, other respiratory viruses were diagnosed in almost 60% of the samples. These observations are a reminder that many different viral transmissions occur simultaneously in countries with ongoing spread of influenza A(H1N1)v. The findings demonstrate that the definition of suspected cases by clinical and epidemiological criteria has only a poor capacity for discriminating influenza A(H1N1)v from other viral infections.