Assessing public health preparedness and response in the European Union- a review of regional simulation exercises and after action reviews.

BACKGROUND: Improving response capacities in the EU requires a good overview of capacities at both country and Union level. The International Health Regulations (2005) Monitoring and Evaluation framework assesses capacities in countries. It includes semi-quantitative tools such as State Parties Annual Report (SPAR) and Joint External Evaluation (JEE). After Action Reviews (AAR) and Simulation Exercises (SimEx) were included to identify weaknesses in the functionality of capacities which are not addressed bySPAR and JEE. This study presents an analysis of the use of qualitative tools at regional level, in Europe. It aims to identify their added value by comparing them to standardised monitoring tools and lessons learned from COVID-19, and considers ways to improve their use in assessing capacities in the EU. METHODS: We included 17 SimEx and 2 AAR organised by the European Commission between 2005 and 2018. We categorised a total of 357 recommendations according to the IHR (2005) core capacities and to the target audience of the recommendation. We analysed the data using language analysis software. Recommendations to countries were compared to SPAR and JEE indicators. Recommendations to EU agencies were compared to the current mandates of the EU agencies, and to lessons learnt during COVID-19. RESULTS: Of all extracted recommendations from the exercises, 59% (211/357) targeted EU agencies, 18% (64/357) targeted countries, and 16% (57/357) targeted both. Recommendations mainly addressed areas of IHR coordination (C2), heath emergency management (C7) and risk communication (C10), and not low scoring areas. Recommendations complement SPAR indicators by identifying gaps in functionality. Eight out of ten early lessons learnt during the COVID-19 pandemic had been raised earlier as recommendations from exercises. Exercise reports did not include or result in action plans for implementation, but COVID-19 has accelerated implementation of some recommendations. CONCLUSION: SimEx/AAR provide valuable insight into public health preparedness at EU level, as they assess functionality of preparedness and response mechanisms, point out gaps, and provide training and awareness on for participants, who often have key roles in public health emergencies. Better follow-up and implementation of recommendations is key to improve the regional preparedness for international public health incidents such as pandemics.

Experiences with regular testing of students for SARS-CoV-2 in primary and secondary schools: results from a cross-sectional study in two Norwegian counties, autumn 2021.

BACKGROUND: To allow for normal school attendance during the COVID-19 pandemic, regular testing of students was introduced in the autumn 2021 in Norway to manage COVID-19 transmission. We mapped the experiences of five stakeholders (parents, students, school staff and administration, contact tracing teams) regarding the implementation of regular testing in primary and secondary schools in Oslo and Viken counties, to assess the acceptability through different indicators and improve future guidelines. METHODS: A cross-sectional survey was conducted between October and November 2021 to explore experiences of implementation, compliance, satisfaction, difficulties, concerns, confidence in regular testing, quality of teaching and school attendance. Five stakeholder groups were invited to participate: contact tracing teams; school administrators and employees in primary, lower secondary, and upper-secondary school; students in upper-secondary school and parents of primary and lower secondary students. Bivariate analyses were performed for students, parents, and school employees groups. Descriptive analyses were done for contact tracing teams and school administrators. RESULTS: Four thousand five hundred sixty-five participants were included in our study. School attendance increased for most of the students in primary and lower secondary schools in Oslo and Viken after the implementation of regular testing. Students across all school levels reported high testing compliance and satisfaction with the implementation. Compliance was significantly associated with an increasing number of weekly tests across all school levels up to two weekly tests. Contact tracing teams were less satisfied with the cooperation with the educational authorities compared to the school employees. Higher educational level of parents was significantly associated with decreased concern of their children getting infected at school after regular testing implementation. Concerned parents were more likely to keep children at home from school, to protect all household members from becoming infected. Lack of time and communication were reported as challenging factors to implementation. CONCLUSION: Compliance, satisfaction, and confidence in regular testing of COVID-19 were high among stakeholders. An acceptable testing regime for a future regular testing implementation would be a home-based, bi-weekly test. Increased awareness of the importance of school attendance, safety of regular testing along with good communication and role clarification should be prioritized for stakeholders involved in regular testing.

Epidemiological and microbiological investigation of a large increase in vibriosis, northern Europe, 2018.

BackgroundVibriosis cases in Northern European countries and countries bordering the Baltic Sea increased during heatwaves in 2014 and 2018.AimWe describe the epidemiology of vibriosis and the genetic diversity of Vibrio spp. isolates from Norway, Sweden, Denmark, Finland, Poland and Estonia in 2018, a year with an exceptionally warm summer.MethodsIn a retrospective study, we analysed demographics, geographical distribution, seasonality, causative species and severity of non-travel-related vibriosis cases in 2018. Data sources included surveillance systems, national laboratory notification databases and/or nationwide surveys to public health microbiology laboratories. Moreover, we performed whole genome sequencing and multilocus sequence typing of available isolates from 2014 to 2018 to map their genetic diversity.ResultsIn 2018, we identified 445 non-travel-related vibriosis cases in the study countries, considerably more than the median of 126 cases between 2014 and 2017 (range: 87-272). The main reported mode of transmission was exposure to seawater. We observed a species-specific geographical disparity of vibriosis cases across the Nordic-Baltic region. Severe vibriosis was associated with infections caused by Vibrio vulnificus (adjOR: 17.2; 95% CI: 3.3-90.5) or Vibrio parahaemolyticus (adjOR: 2.1; 95% CI: 1.0-4.5), age ≥ 65 years (65-79 years: adjOR: 3.9; 95% CI: 1.7-8.7; ≥ 80 years: adjOR: 15.5; 95% CI: 4.4-54.3) or acquiring infections during summer (adjOR: 5.1; 95% CI: 2.4-10.9). Although phylogenetic analysis revealed diversity between Vibrio spp. isolates, two V. vulnificus clusters were identified.ConclusionShared sentinel surveillance for vibriosis during summer may be valuable to monitor this emerging public health issue.

Exotic dried fruits caused Salmonella Agbeni outbreak with severe clinical presentation, Norway, December 2018 to March 2019.

We describe an outbreak of Salmonella Agbeni sequence type (ST)2009 infections in Norway. Between 31 December 2018 and 16 March 2019, 56 cases (33 female and 23 male; median age: 50 years, range: 2-91) were reported, of which 21 were hospitalised. Cases were defined as people living in Norway, with laboratory-confirmed infection with S. Agbeni ST2009 and cluster type (CT)2489, reported between 31 December 2018 and 30 March 2019. We conducted a case-control study, with three controls per case (matched by age, sex and municipality), using the Norwegian National Registry. Cases were more likely to have consumed a commercial mix of dried exotic fruits than controls (cases = 8, controls = 31; odds ratio: 50; 95% confidence interval: 3-2,437). The outbreak strain was confirmed by whole genome sequencing (WGS) and was isolated from the fruit mix consumed by cases, resulting in withdrawal from the market on 6 March 2019.The fruit mix consisted of fruits from different countries and continents. It was packed in Italy and distributed to several European countries, including Norway. However, no other countries reported cases. This outbreak highlights that dried fruits could represent a risk in terms of food-borne infections, which is of particular concern in ready-to-eat products.

Outbreak caused by the SARS-CoV-2 Omicron variant in Norway, November to December 2021.

In late November 2021, an outbreak of Omicron SARS-CoV-2 following a Christmas party with 117 attendees was detected in Oslo, Norway. We observed an attack rate of 74% and most cases developed symptoms. As at 13 December, none have been hospitalised. Most participants were 30-50 years old. Ninety-six percent of them were fully vaccinated. These findings corroborate reports that the Omicron variant may be more transmissible, and that vaccination may be less effective in preventing infection compared with Delta.

Large waterborne Campylobacter outbreak: use of multiple approaches to investigate contamination of the drinking water supply system, Norway, June 2019.

On 6 June 2019, the Norwegian Institute of Public Health was notified of more than 50 cases of gastroenteritis in Askøy. A reservoir in a water supply system was suspected as the source of the outbreak because of the acute onset and geographical distribution of cases. We investigated the outbreak to confirm the source, extent of the outbreak and effect of control measures. A case was defined as a person in a household served by Water Supply System A (WSS-A) who had gastroenteritis for more than 24 h between 1 and 19 June 2019. We conducted pilot interviews, a telephone survey and an SMS-based cohort study of residents served by WSS-A. System information of WSS-A was collected. Whole genome sequencing on human and environmental isolates was performed. Among 6,108 individuals, 1,573 fulfilled the case definition. Residents served by the reservoir had a 4.6× higher risk of illness than others. Campylobacter jejuni isolated from cases (n = 24) and water samples (n = 4) had identical core genome MLST profiles. Contamination through cracks in the reservoir most probably occurred during heavy rainfall. Water supply systems are susceptible to contamination, particularly to certain weather conditions. This highlights the importance of water safety planning and risk-based surveillance to mitigate risks.

Reporting of notifiable infectious diseases during the COVID-19 response. / Registrerte meldingspliktige smittsomme sykdommer under covid-19-responsen.

BACKGROUND: The Norwegian Surveillance System for Communicable Diseases (MSIS) is based on reporting of cases of 72 mandatory notifiable diseases by clinical microbiological laboratories and diagnosing physicians. The aim of our study was to investigate a potential temporal association between measures against COVID-19 in February-April 2020 and incidence of other infectious diseases reported to MSIS. MATERIAL AND METHOD: We compared the number of disease cases reported to MSIS during weeks 6-14 in 2020 with the median of cases reported in corresponding weeks during three previous years (2017-2019). RESULTS: Compared to the median of cases reported during corresponding weeks in three previous years, physicians and laboratories reported 47 % fewer cases (159 vs. 301) in week 12, 50 % fewer cases (131 vs. 261) in week 13, and 69 % fewer cases (77 vs. 252) in week 14. There was a reduction in the number of notifications of all included disease groups. INTERPRETATION: The observed decline in reporting of diseases other than COVID-19 may indicate a reduced risk of communicable diseases due to comprehensive advice and the requirement for social distancing. However, it is also possible that the sensitivity of the surveillance system was affected by increased resource use on COVID-19 cases management.

COVID-19 cases reported to the Norwegian Institute of Public Health in the first six weeks of the epidemic. / Covid-19 rapportert til Folkehelseinstituttet de første seks ukene av epidemien.

BACKGROUND: The first case of SARS-CoV-2 infection in Norway was confirmed on 26 February 2020. Following sharpened advice on general infection control measures at the beginning of the outbreak, extensive national control measures were implemented on 12 March, and testing was focused on those with severe illness. We describe the first six weeks of the outbreak in Norway, viewed in light of testing criteria and control measures. MATERIAL AND METHOD: We described all laboratory-confirmed cases of COVID-19 reported to three different surveillance systems under the Norwegian Institute of Public Health up to 5 April 2020, and compared cases reported up to 12 March with those reported from 13 March. RESULTS: By 12 March, 1 128 cases had been reported. Their median age was 47 years, 64 % were male, 66 % had travelled abroad, 6 % were hospitalised at the time of reporting, and < 1 % had died. The median age of the 4 742 cases reported from 13 March was 48 years, 47 % were male, 18 % had travelled abroad, 15 % were hospitalised, and 3 % died. INTERPETATION: The distribution of COVID-19 cases before and after 12 March reflects different phases of the outbreak. However, findings must be interpreted in the light of criteria for testing, testing activity, control measures and characteristics of surveillance systems.

Evaluation of the national surveillance of Legionnaires' disease in Norway, 2008-2017.

BACKGROUND: In Norway, Legionnaires' disease is reportable upon clinical suspicion to public health authorities and mandatorily notifiable through the Norwegian surveillance system for communicable diseases (MSIS) for both clinicians and laboratories. In the summer of 2017, several European countries reported high notification rates for Legionnaires' disease, which was not observed in Norway. We evaluated MSIS to assess if it meets its objectives of detecting cases and trends in incidence of Legionnaires' disease. METHODS: We retrieved MSIS data from 2008 to 2017 and calculated timeliness as days from sampling to notification, and internal completeness for key variables as the proportion of observations with a value. Where possible, we assessed internal validity on the presence of a plausible value. To estimate external completeness and validity we linked MSIS with hospital reimbursement claims in the Norwegian Patient Registry. To assess acceptability and representativeness, we surveyed doctors in 39 hospitals on their units' diagnostic and notification procedures, and their use of MSIS. RESULTS: There were 438 notified cases. Internal completeness and internal validity were high for key variables (≥95%). The median delay from sampling to notification was 4 days. There were 73 patients in MSIS only, 70 in the Norwegian Patient Registry only, and 351 in both registers. The external completeness of MSIS was 83% (95% CI 80-86%). For external validity, the positive predictive value of MSIS was 83% (95% CI 79-86%). Forty-seven respondents from 28 hospitals described testing procedures. These were inconsistent: 29 (62%) reported no systematic application of criteria for requesting legionella testing. Eighteen (38%) reported testing all patients with suspected pneumonia and a travel history. Thirty-one (66%) found the notification criteria clear. CONCLUSIONS: Our results suggest that the surveillance in MSIS can detect incidence changes for Legionnaires' disease over time, by place and person, but likely does not detect every case diagnosed in Norway. We recommend wider investigation of diagnostic procedures in order to improve representativeness and awareness of MSIS notification criteria among clinicians in order to improve acceptability of the surveillance. We also recommend a more comprehensive assessment of whether patients only registered in the Norwegian Patient Registry were true Legionnaires' disease cases.

An outbreak of skin rash traced to a portable floating tank in Norway, May 2017.

Despite concerns about infection risks of floating tanks, outbreaks have rarely been reported. In May 2017, an outbreak of skin rash occurred among visitors of a floating tank open for the public in Norway. We assessed the extent and cause of the outbreak and the risk factors for infection in a retrospective cohort study among the visitors of the floating tank using a standardized web-based questionnaire. An environmental investigation was conducted including microbiological analysis of the floating tank water. Of the 46 respondents to the questionnaire (61 distributed), 22 reported symptoms, most commonly palmar and plantar rash, swollen lymph nodes, ear canal pain and itching. None of the investigated risk factors, such as sex, age, duration of bathing or use of the shower after bathing, were significantly associated with illness. The results of the environmental investigation indicated that the water was heavily contaminated by P. aeruginosa and heterotrophic bacteria. The outbreak investigation highlights the need to ensure adequate hygienic operation of floating tanks. Awareness about responsibilities should be raised among the operators of floating tanks and relevant operational parameters for floating tanks should be made available for local health authorities.

Increasing incubation periods during a prolonged monophasic Salmonella Typhimurium outbreak with environmental contamination of a commercial kitchen at Oslo Airport, Norway, 2017.

In September 2017, a cluster of monophasic Salmonella Typhimurium isolates was identified at the National Reference Laboratory for Enteropathogenic Bacteria in Norway. We investigated the cluster to identify the source and implement control measures. We defined a case as a person with laboratory-confirmed salmonellosis with the outbreak strain multiple locus variable-number tandem repeat analysis type. We conducted descriptive epidemiological and environmental investigations and performed whole genome sequencing (WGS) with core and accessory genome multilocus sequence typing of all isolates from cases or the environment connected with this outbreak. We identified 21 cases, residing in 10 geographically dispersed counties, all of whom had consumed food or drinks from a café at Oslo Airport. Case distribution by date of symptom onset suggested that a point source was introduced in mid-August followed by continued environmental contamination. The incubation periods ranged 0-16 days and increased as the outbreak progressed, likely due to increasingly low-dose exposure as control measures were implemented. WGS confirmed an identical cluster type-944 in all cases and six environmental specimens from the café. Control measures, including temporary closure and kitchen refurbishment, failed to eliminate the environmental source. We recommend strengthened hygiene measures for established environmental contamination during an outbreak.

Oral cholera vaccine in cholera prevention and control, Malawi.

PROBLEM: With limited global supplies of oral cholera vaccine, countries need to identify priority areas for vaccination while longer-term solutions, such as water and sanitation infrastructure, are being developed. APPROACH: In 2017, Malawi integrated oral cholera vaccine into its national cholera control plan. The process started with a desk review and analysis of previous surveillance and risk factor data. At a consultative meeting, researchers, national health and water officials and representatives from nongovernmental and international organizations reviewed the data and local epidemiological knowledge to determine priority districts for oral cholera vaccination. The final stage was preparation of an application to the global oral cholera vaccine stockpile for non-emergency use. LOCAL SETTING: Malawi collects annual data on cholera and most districts have reported cases at least once since the 1970s. RELEVANT CHANGES: The government's application for 3.2 million doses of vaccine to be provided over 20 months in 12 districts was accepted in April 2017. By April 2018, over 1 million doses had been administered in five districts. Continuing surveillance in districts showed that cholera outbreaks were notably absent in vaccinated high-risk areas, despite a national outbreak in 2017-2018. LESSONS LEARNT: Augmenting advanced mapping techniques with local information helped us extend priority areas beyond those identified as high-risk based on cholera incidence reported at the district level. Involvement of the water, sanitation and hygiene sectors is key to ensuring that short-term gains from cholera vaccine are backed by longer-term progress in reducing cholera transmission.

Surgical frailty assessment: a missed opportunity.

BACKGROUND: Preoperative frailty predicts adverse postoperative outcomes. Despite the advantages of incorporating frailty assessment into surgical settings, there is limited research on surgical healthcare professionals' use of frailty assessment for perioperative care. METHODS: Healthcare professionals caring for patients enrolled at a Canadian teaching hospital were surveyed to assess their perceptions of frailty, as well as attitudes towards and practices for frail patients. The survey contained open-ended and 5-point Likert scale questions. Responses were compared across professions using independent sample t-tests and correlations between survey items were analyzed. RESULTS: Nurses and allied health professionals were more likely than surgeons to think frailty should play a role in planning a patient's care (nurses vs. surgeons p = 0.008, allied health vs. surgeons p = 0.014). Very few respondents (17.5%) reported that they 'always used' a frailty assessment tool. Results from qualitative data analysis identified four main barriers to frailty assessment: institutional, healthcare system, professional knowledge, and patient/family barriers. CONCLUSION: Across all disciplines, the lack of knowledge about frailty issues was a prominent barrier to the use of frailty assessments in practice, despite clinicians' understanding that frailty affects their patients' outcomes. Confidence in frailty assessment tool use through education and addressing barriers to implementation may increase use and improve patient care. Healthcare professionals agree that frailty assessments should play a role in perioperative care. However, few perform them in practice. Lack of knowledge about frailty is a key barrier in the use of frailty assessments and the majority of respondents agreed that they would benefit from further training.

Is current preoperative frailty assessment adequate?

SUMMARY: Preoperative frailty predicts adverse postoperative outcomes. Recommendations for preoperative assessment of elderly patients include performing a frailty assessment. Despite the advantages of incorporating frailty assessment into surgical settings, there is limited research on surgical health care professionals' perception and use of frailty assessment for perioperative care. We surveyed local health care employees to assess their attitudes toward and practices for frail patients. Nurses and allied health professionals were more likely than surgeons to agree frailty should play a role in planning a patient's care. Lack of knowledge about frailty issues was a prominent barrier to the use of frailty assessments in practice, despite clinicians understanding that frailty affects their patients' outcomes. Results of this survey suggest further training in frailty issues and the use of frailty assessment instruments is necessary and could improve the uptake of such tools for perioperative care planning.

Water usage in the Gaza Strip: recommendations from a literature review and consultations with experts.

Water quality in the Gaza Strip has been severely compromised due to increasing salinity, contamination with pollutants, and lack of adequate treatment options. To provide the population of the Gaza Strip with advice on how to mitigate health risks from water we developed recommendations on using water from different sources for different purposes (such as for consumption, hygiene, amenities, and irrigation) based on a literature review and consultation with experts. Specific advice was developed for several vulnerable groups, including infants, children, pregnant or lactating women, and elderly people. The recommendations are inherently limited, as it is unacceptable to recommend consuming water that is of substandard quality. However, pending long-term solutions, information can be targeted to vulnerable groups to ensure that exposure to the most harmful contaminants is avoided. The implementation of these recommendations may require information campaigns to assist the population in differentiating water from different sources for different uses.

Integration of Genomic and Other Epidemiologic Data to Investigate and Control a Cross-Institutional Outbreak of Streptococcus pyogenes.

Single-strain outbreaks of Streptococcus pyogenes infections are common and often go undetected. In 2013, two clusters of invasive group A Streptococcus (iGAS) infection were identified in independent but closely located care homes in Oxfordshire, United Kingdom. Investigation included visits to each home, chart review, staff survey, microbiologic sampling, and genome sequencing. S. pyogenes emm type 1.0, the most common circulating type nationally, was identified from all cases yielding GAS isolates. A tailored whole-genome reference population comprising epidemiologically relevant contemporaneous isolates and published isolates was assembled. Data were analyzed independently using whole-genome multilocus sequencing and single-nucleotide polymorphism analyses. Six isolates from staff and residents of the homes formed a single cluster that was separated from the reference population by both analytical approaches. No further cases occurred after mass chemoprophylaxis and enhanced infection control. Our findings demonstrate the ability of 2 independent analytical approaches to enable robust conclusions from nonstandardized whole-genome analysis to support public health practice.

Association between heavy precipitation events and waterborne outbreaks in four Nordic countries, 1992-2012.

We conducted a matched case-control study to examine the association between heavy precipitation events and waterborne outbreaks (WBOs) by linking epidemiological registries and meteorological data between 1992 and 2012 in four Nordic countries. Heavy precipitation events were defined by above average (exceedance) daily rainfall during the preceding weeks using local references. We performed conditional logistic regression using the four previous years as the controls. Among WBOs with known onset date (n = 89), exceedance rainfall on two or more days was associated with occurrence of outbreak, OR = 3.06 (95% CI 1.38-6.78), compared to zero exceedance days. Stratified analyses revealed a significant association with single household water supplies, ground water as source and for outbreaks occurring during spring and summer. These findings were reproduced in analyses including all WBOs with known outbreak month (n = 186). The vulnerability of single households to WBOs associated with heavy precipitation events should be communicated to homeowners and implemented into future policy planning to reduce the risk of waterborne illness.

Are the current notification criteria for Lyme borreliosis in Norway suitable? Results of an evaluation of Lyme borreliosis surveillance in Norway, 1995-2013.

BACKGROUND: The approach to surveillance of Lyme borreliosis varies between countries, depending on the purpose of the surveillance system and the notification criteria used, which prevents direct comparison of national data. In Norway, Lyme borreliosis is notifiable to the Surveillance System for Communicable Diseases (MSIS). The current notification criteria include a combination of clinical and laboratory results for borrelia infection (excluding Erythema migrans) but there are indications that these criteria are not followed consistently by clinicians and by laboratories. Therefore, an evaluation of Lyme borreliosis surveillance in Norway was conducted to describe the purpose of the system and to assess the suitability of the current notification criteria in order to identify areas for improvement. METHODS: The CDC Guidelines for Evaluation of Surveillance Systems were used to develop the assessment of the data quality, representativeness and acceptability of MSIS for surveillance of Lyme borreliosis. Data quality was assessed through a review of data from 1996 to 2013 in MSIS and a linkage of MSIS data from 2008 to 2012 with data from the Norwegian Patient Registry (NPR). Representativeness and acceptability were assessed through a survey sent to 23 diagnostic laboratories. RESULTS: Completeness of key variables for cases reported to MSIS was high, except for geographical location of exposureThe NPR-MSIS linkage identified 1047 cases in both registries, while 363 were only reported to MSIS and 3914 were only recorded in NPR. A higher proportion of cases found in both registries were recorded as neuroborreliosis in MSIS (84.4 %) than those cases found only in MSIS (20.1 %). The trend (average yearly increase or decrease in reported cases) of neuroborreliosis in MSIS was not significantly different from the trend for all other clinical manifestations recorded in MSIS in negative binomial regression (p = 0.3). The 16 surveyed laboratories (response proportion 70 %) indicated differences in testing practices and low acceptability of the notification criteria. CONCLUSIONS: Given the challenges associated with diagnosing Lyme borreliosis, the selected notification criteria should be closely linked with the purpose of the surveillance system. Restricting reportable Lyme borreliosis to neuroborreliosis may increase validity, while a more sensitive case definition (potentially including erythema migrans) may better reflect the true burden of disease. We recommend revising the current notification criteria in Norway to ensure that they are unambiguous for clinicians and laboratories.

National outbreak of Yersinia enterocolitica infections in military and civilian populations associated with consumption of mixed salad, Norway, 2014.

In May 2014, a cluster of Yersinia enterocolitica (YE) O9 infections was reported from a military base in northern Norway. Concurrently, an increase in YE infections in civilians was observed in the Norwegian Surveillance System for Communicable Diseases. We investigated to ascertain the extent of the outbreak and identify the source in order to implement control measures. A case was defined as a person with laboratory-confirmed YE O9 infection with the outbreak multilocus variable-number tandem repeat analysis (MLVA)-profile (5-6-9-8-9-9). We conducted a case-control study in the military setting and calculated odds ratios (OR) using logistic regression. Traceback investigations were conducted to identify common suppliers and products in commercial kitchens frequented by cases. By 28 May, we identified 133 cases, of which 117 were linked to four military bases and 16 were civilians from geographically dispersed counties. Among foods consumed by cases, multivariable analysis pointed to mixed salad as a potential source of illness (OR 10.26; 95% confidence interval (CI): 0.85-123.57). The four military bases and cafeterias visited by 14/16 civilian cases received iceberg lettuce or radicchio rosso from the same supplier. Secondary transmission cannot be eliminated as a source of infection in the military camps. The most likely source of the outbreak was salad mix containing imported radicchio rosso, due to its long shelf life. This outbreak is a reminder that fresh produce should not be discounted as a vehicle in prolonged outbreaks and that improvements are still required in the production and processing of fresh salad products.

[Waterborne outbreaks in Norway 2003-2012]. / Vannbårne utbrudd i Norge i perioden 2003-12.

BACKGROUND: We describe the status of waterborne outbreaks notified in Norway and discuss this in the context of outbreaks recorded in previous years, to gain a better understanding of their development in Norway in recent years. MATERIAL AND METHOD: We have collected information on all outbreaks notified to the Norwegian Institute of Public Health via the surveillance system for communicable diseases in the ten-year period from 2003-2012 for which drinking water was given as the suspected cause. RESULTS: Altogether 28 waterborne outbreaks with a total of 8,060 persons reported as ill were notified in the period. The majority of outbreaks resulted in fewer than 100 cases of illness. There were two outbreaks with more than 1,000 cases of illness: an oubreak of campylobacteriosis in Røros and an oubreak of giardiasis in Bergen. In more than half of the outbreaks, water was supplied from public water distribution systems (16/28 outbreaks, 57%). In addition, a large proportion was linked to individual households with their own water supply (12/28 outbreaks, 43%). INTERPRETATION: Most of the outbreaks in the ten-year period were linked to public water distribution systems, while almost half were linked to non-disinfected water supplies to individual households. Although most of the outbreaks were small, two extensive outbreaks were also registered in the period, resulting in more than one thousand cases of illness. This underscores the need for good contingency planning and surveillance, so that suspicion of waterborne outbreaks is rapidly notified to the responsible authorities, and the importance of good protection of water sources, as well as proper maintenance of water treatment plants and distribution systems.