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In the period from May through June 1994, an increase in the number of domestic cases of Shigella sonnei infection was detected in several European countries, including Norway, Sweden, and the United Kingdom. In all three countries epidemiological evidence incriminated imported iceberg lettuce of Spanish origin as the vehicle of transmission. The outbreaks shared a number of common features: a predominance of adults among the case patients, the presence of double infections with other enteropathogens, and the finding of two dominant phage types among the bacterial isolates. In Norway 110 culture-confirmed cases of infection were recorded; more than two-thirds (73%) were adults aged 30 to 60 years. A nationwide case-control study comprising 47 case patients and 155 matched control individuals showed that the consumption of imported iceberg lettuce was independently associated with an increased risk of shigellosis. Epidemiological investigation of a local outbreak incriminated iceberg lettuce from Spain, consumed from a salad bar, as the source. The presence of shigellae in the suspected food source could not be documented retrospectively. However, high numbers of fecal coliforms were detected in iceberg lettuce from patients' homes. Three lettuce specimens yielded salmonellae. The imported iceberg lettuce harbored Escherichia coli strains showing resistance to several antimicrobial agents, including ampicillin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole. During the outbreak it is likely that thousands of Norwegians and an unknown number of consumers in other countries were exposed to coliforms containing antibiotic resistance genes.

Contamination of mouth swabs during production caused the largest-ever outbreak of P. aeruginosa infection in Norway. Susceptible patient groups should use only documented quality-controlled, high-level-disinfected products and items in the oropharynx.

Influenza can be a serious, sometimes deadly, disease, especially for people in high-risk groups such as the elderly and patients with underlying, severe disease. In this paper we estimated the influenza-related excess mortality in Norway for 1975-2004, comparing it with dominant virus types and estimates of the reproduction number. Analysis was done using Poisson regression, explaining the weekly all-cause mortality by rates of reported influenza-like illness, together with markers for seasonal and year-to-year variation. The estimated excess mortality was the difference between the observed and predicted mortality, removing the influenza contribution from the prediction. We estimated the overall influenza-related excess mortality as 910 deaths per season, or 2.08% of the overall deaths. Age-grouped analyses indicated that the major part of the excess mortality occurred in the > or =65 years age group, but that there was also a significant contribution to mortality in the 0-4 years age group. Estimates of the reproduction number R, ranged from about 1 to 1.69.

We analysed data on all cases of meningococcal disease (MCD) reported to the Norwegian Notification System for Infectious Diseases during the period 1992-1995. For 1994, additional information on fatalities was gathered. Notifications were received from laboratories and clinicians. A total of 586 patients were included. The incidence decreased from 4.6 per 100000 in 1992 to 2.4 in 1994, and then rose to 3.7 in 1995. The initial decrease, a trend also observed in previous years, was seen in both main serogroups B and C. This decline was broken with the increase of serogroup B in 1995. MCD predominantly affects children below 5 years and teenagers. In 1994, 17/105 (16%) patients died. Main risk factors for fatal outcome were age above 30 years (adjusted odds ratio (OR) 19.8; 95% confidence interval (CI) 2.4-164), septicaemia (adjusted OR 9.5; 95% CI 2.2-41) and disease caused by strains B:15 (adjusted OR 6.4; 95% CI 1.2-35) or C:2a (adjusted OR 10.1; 95% CI 1.6-62). We conclude that the incidence of MCD in Norway is unpredictable and that the case fatality rate is substantially higher than previously believed.

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