Eurosurveillance - Volume 14, Issue 10, 12 March 2009

This is the first case of Lassa fever to be imported from Mali to the United Kingdom. This paper discusses the investigations, the virological analysis, the surveillance and management of contacts undertaken following a case of Lassa fever.

West Nile disease in humans has been detected for the first time in Italy in two regions, Emilia-Romagna and Veneto. Surveillance subsequently set up in Veneto detected a case of West Nile neuroinvasive disease and a few asymptomatic infections, but no case of West Nile fever. We conclude that also West Nile fever cases should be specifically targeted by surveillance.

In November-December 2008, Norway and Denmark independently identified outbreaks of Salmonella Typhimurium infections characterised in the multiple-locus variable number of tandem repeats analysis (MLVA) by a distinct profile. Outbreak investigations were initiated independently in the two countries. In Denmark, a total of 37 cases were identified, and multiple findings of the outbreak strain in pork and pigs within the same supply chain led to the identification of pork in various forms as the source. In Norway, ten cases were identified, and the outbreak investigation quickly indicated meat bought in Sweden as the probable source and the Swedish authorities were alerted. Investigations in Sweden identified four human cases and two isolates from minced meat with the distinct profile. Subsequent trace-back of the meat showed that it most likely originated from Denmark. Through international alert from Norway on 19 December, it became clear that the Danish and Norwegian outbreak strains were identical and, later on, that the source of the outbreaks in all three countries could be traced back to Danish pork. MLVA was instrumental in linking the outbreaks in the different countries and tracing the source. This outbreak illustrates that good international communication channels, early alerting mechanisms, inter-sectoral collaboration between public health and food safety authorities and harmonised molecular typing tools are important for effective identification and management of cross-border outbreaks. Differences in legal requirements for food safety in neighbouring countries may be a challenge in terms of communication with consumers in areas where cross-border shopping is common.

Following the notification of nine hepatitis A cases clustered in the Côtes d'Armor district in northwestern France, epidemiological, environmental and microbiological investigations were set up in order to identify the source and vehicle of contamination and implement control measures. In total, 111 cases were identified in the outbreak, all of whom lived or had stayed as tourists in the Côtes d'Armor district. Of the cases, 87% had eaten raw shellfish, and 81% specifically oysters. Traceback investigations carried out on raw shellfish consumed by the cases showed that the raw shellfish originated from a single shellfish farm. The shellfish were probably contaminated either in the submersible tanks or in a depuration land-based tank where they were stored. The source of contamination was not identified but shellfish could have been tainted by sewage overflows or by wastewater releases from a polluted storm sewer close to the shellfish farm or from on-site sanitation facilities. To prevent future hepatitis A outbreaks due to shellfish consumption from this area, hazards specific to each farm should be analysed. Timely information on sewage overflows should also be part of communities' efforts regarding sewage collection and treatment. .

Information regarding the current seroprevalence of hepatitis A virus (HAV) is useful for the control of HAV infections. The objective of our study was to evaluate the prevalence of anti-HAV antibodies among children (1-5 years old) and young adults (15-20 years old) in Tuscany, in central Italy. A total of 565 sera were collected in three years 1992, 1998 and 2004, equally distributed between the two age groups. The overal proportion of those that tested positive for anti-HAV antibodies was 8.3%. The proportion of immune children (1-5 years old) statistically significantly increased over the years. The percentage of immune subjects among 15-20-year-old young adults varied over the years, not showing a significant statistical trend, nevertheless our findings indicate that in a low endemicity area, adolescents and young adults are becoming increasingly susceptible to HAV infection. On-going monitoring of immunity to HAV is necessary for detecting trends over time.