Large outbreak of mumps virus genotype G among vaccinated students in Norway, 2015 to 2016.

From 6 September 2015-May 2016, a large mumps outbreak occurred among vaccinated students in Norway. A case was defined as a person presenting with a clinical mumps infection, notified between 1 September 2015 and 30 June 2016. Confirmed cases had positive laboratory confirmation and probable cases had an epidemiological link; PCR-positive specimens were genotyped. A total of 232 cases were notified (230 confirmed) with median age of 23 years (range 4-81) and 61% were male. Of 68 (30%) confirmed cases that were genotyped, 66 were genotype G and associated with the outbreak. Cases that had received two doses of the measles-mumps-rubella (MMR) vaccine had reduced risk of hospitalisation (adjusted relative risk (aRR): 0.14; 95%CI: 0.03-0.57), mumps-related orchitis (aRR: 0.21; 95% CI: 0.08-0.55) and severe outcome (aRR: 0.25; 95% CI: 0.10-0.62) compared with those unvaccinated. A third dose of the vaccine was offered to approximately 1,300 fully vaccinated close contacts and subsequently reported cases decreased. This large outbreak, occurring among predominately vaccinated students, suggests the current genotype A vaccine offers suboptimal protection against mumps genotype G. We recommend maintaining high vaccination coverage and offering the vaccine to all unvaccinated individuals.

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.

Importance of molecular typing in confirmation of the source of a national hepatitis A virus outbreak in Norway and the detection of a related cluster in Germany.

In March 2014, after an increase of notifications of domestically acquired hepatitis A virus infections, an outbreak investigation was launched in Norway. Sequenced-based typing results showed that these cases were associated with a strain that was identical to one causing an ongoing multinational outbreak in Europe linked to frozen mixed berries. Thirty-three confirmed cases with the outbreak strain were notified in Norway from November 2013 to June 2014. Epidemiological evidence and trace-back investigations linked the outbreak to the consumption of a berry mix cake. Identification of the hepatitis A virus outbreak strain in berries from one of the implicated cakes confirmed the cake to be the source. Subsequently, a cluster in Germany linked to the cake was also identified.

Description of the largest cluster of tuberculosis notified in Norway 1997-2011: is the Norwegian tuberculosis control programme serving its purpose for high risk groups?

BACKGROUND: Approximately 90% of new tuberculosis (TB) cases notified in Norway are asylum seekers and other immigrants from high-incidence countries. Asylum seekers are screened upon arrival at the National Immigration Centre. Other immigrants receive a letter from the Municipal Health Services requesting that they present for screening in their municipality of residence. In order to identify potential areas where the TB control programme could be better adapted for these groups, we studied the largest cluster of TB cases ("cluster X") notified in Norway until 2011. METHODS: Cases were defined as TB notifications reported to MSIS between January 1997 and December 2011 with identical IS6110 RFLP assigned to cluster X. We described the cases in cluster X by using data from the Norwegian Surveillance System for Communicable Diseases (MSIS). Missing or incomplete information in MSIS was obtained from the National Reception Centre, Oslo University Hospital and Municipal Health services. RESULTS: Of a total of 44 individuals meeting the case definition, 36 originated from Somalia and eight from other high-incidence countries. Twenty nine were asylum seekers and 15 were other immigrants. Upon arrival, 18/44 had been diagnosed with latent TB infection (LTBI), 9/44 tested negative for LTBI and 4/44 had been diagnosed with active TB. Results of TB-screening upon arrival were not available for the remaining 13/44 (one asylum seeker and 12 other immigrants). Five of the 12 other immigrants had still not been screened for TB after staying one year or longer in Norway. CONCLUSIONS: Most cases in cluster X with available results of TB-screening were already infected at arrival, indicating that their disease could be due to endogenous reactivation, rather than recent transmission after arrival to Norway. TB-status upon arrival was unknown for many of the other immigrants due to lack of initial screening. The reasons why conduction of the initial screening among other immigrants is failing should be explored and methods to simplify the TB screening at arrival should be implemented.

Molecular characterization of clinical and environmental isolates of Legionella pneumophila in Norway, 2001-2008.

BACKGROUND: The aims of the study were to determine the molecular characteristics of a collection of Legionella pneumophila isolates from 45 cases with Legionnaires' disease and from 96 environmental samples, received by the national reference laboratory in Norway between 2001 and 2008, to use these characteristics to identify links between cases and suspected sources of infection, and to compare the isolate characteristics with those in other European countries. METHODS: The isolates were characterized by 7-gene locus sequence-based typing and dot-blotting with monoclonal antibodies to various serogroups and subgroups. RESULTS: The clinical isolates represented 12.6% of the 357 cases notified in Norway between 2001 and 2008, during which 3 outbreaks of L. pneumophila serogroup 1 occurred. Outbreak cases constituted 62.2% of the cases, followed by travel-associated (24.4%) and sporadic cases (11.1%). Forty-two (93.3%) of the clinical and 69 (71.9%) of the environmental isolates were serogroup 1, and 39 (86.7%) and 50 (52.1%) isolates, respectively, carried the monoclonal antibody (Mab) 3/1 virulence-associated epitope. The clinical isolates belonged to 17 sequence types and the environmental isolates to 19 sequence types. neuA was not detected in 23 environmental isolates. CONCLUSIONS: Matching characteristics of sequence types and monoclonal subgroups for case and environmental isolates were obtained for all 3 outbreaks and for 2 of 5 cases of sporadic disease. Sampling during the outbreaks accounted for the higher proportion of serogroup 1 and Mab 3/1-positive environmental isolates in comparison with other European strain collections.

Usefulness of health registries when estimating vaccine effectiveness during the influenza A(H1N1)pdm09 pandemic in Norway.

BACKGROUND: During the 2009-2010 pandemic in Norway, 12 513 laboratory-confirmed cases of pandemic influenza A(H1N1)pdm09, were reported to the Norwegian Surveillance System for Communicable Diseases (MSIS). 2.2 million persons (45% of the population) were vaccinated with an AS03-adjuvanted monovalent vaccine during the pandemic. Most of them were registered in the Norwegian Immunisation Registry (SYSVAK). Based on these registries, we aimed at estimating the vaccine effectiveness (VE) and describing vaccine failures during the pandemic in Norway, in order to evaluate the role of the vaccine as a preventive measure during the pandemic. METHODS: We conducted a population-based retrospective cohort study, linking MSIS and SYSVAK with pandemic influenza vaccination as exposure and laboratory-confirmed pandemic influenza as outcome. We measured VE by week and defined two thresholds for immunity; eight and 15 days after vaccination. RESULTS: The weekly VE ranged from 77% to 96% when considering 15 days or more after vaccination as the threshold of immunity and from 73% to 94% when considering eight days or more. Overall, 157 individuals contracted pandemic influenza eight or more days after vaccination (8.4/100,000 vaccinated), of these 58 had onset 15 days or more after vaccination (3.0/100,000 vaccinated). Most of the vaccine failures occurred during the first weeks of the vaccination campaign. More than 30% of the vaccine failures were found in people below 10 years of age. CONCLUSIONS: Having available health registries with data regarding cases of specific disease and vaccination makes it feasible to estimate VE in a simple and rapid way. VE was high regardless the immunity threshold chosen. We encourage public health authorities in other countries to set up such registries. It is also important to consider including information on underlying diseases in registries already existing, in order to make it feasible to conduct more complete VE estimations.

Detection of events of public health importance under the international health regulations: a toolkit to improve reporting of unusual events by frontline healthcare workers.

BACKGROUND: The International Health Regulations (IHR (2005)) require countries to notify WHO of any event which may constitute a public health emergency of international concern. This notification relies on reports of events occurring at the local level reaching the national public health authorities. By June 2012 WHO member states are expected to have implemented the capacity to "detect events involving disease or death above expected levels for the particular time and place" on the local level and report essential information to the appropriate level of public health authority. Our objective was to develop tools to assist European countries improve the reporting of unusual events of public health significance from frontline healthcare workers to public health authorities. METHODS: We investigated obstacles and incentives to event reporting through a systematic literature review and expert consultations with national public health officials from various European countries. Multi-day expert meetings and qualitative interviews were used to gather experiences and examples of public health event reporting. Feedback on specific components of the toolkit was collected from healthcare workers and public health officials throughout the design process. RESULTS: Evidence from 79 scientific publications, two multi-day expert meetings and seven qualitative interviews stressed the need to clarify concepts and expectations around event reporting in European countries between the frontline and public health authorities. An analytical framework based on three priority areas for improved event reporting (professional engagement, communication and infrastructure) was developed and guided the development of the various tools. We developed a toolkit adaptable to country-specific needs that includes a guidance document for IHR National Focal Points and nine tool templates targeted at clinicians and laboratory staff: five awareness campaign tools, three education and training tools, and an implementation plan. The toolkit emphasizes what to report, the reporting process and the need for follow-up, supported by real examples. CONCLUSION: This toolkit addresses the importance of mutual exchange of information between frontline healthcare workers and public health authorities. It may potentially increase frontline healthcare workers' awareness of their role in the detection of events of public health concern, improve communication channels and contribute to creating an enabling environment for event reporting. However, the effectiveness of the toolkit will depend on the national body responsible for dissemination and training.

[Disease caused by the new influenza A(H1N1) virus]. / Sykdom forårsaket av nytt A(H1N1)-influensavirus.

BACKGROUND: A new A(H1N1) influenza virus was detected in April 2009. The virus is now causing a pandemic of influenza. The article presents an overview of symptoms, complications, vulnerable groups, diagnosis and treatment. MATERIAL AND METHODS: The overview is based on literature identified through a search in PubMed (using PubMed's own search strategy) and on official reports from WHO and the disease control centres of EU and the USA. RESULTS: The new influenza A(H1N1) has so far mainly affected young people, only few people over 60 years. The clinical presentation is similar to that of ordinary influenza; but nausea, vomiting and diarrhoea seem to be more common. The reported risk of complications and case fatality are low, but hospitalisation, pneumonia and deaths have occurred, also in previously healthy young individuals. Antiviral treatment with oseltamivir or zanamivir is likely to be as effective as in ordinary influenza. INTERPRETATION: Mild cases may be underrepresented in the published literature. It is important to keep up-to-date on international reports on the nature of the disease in order to best prepare clinicians to diagnose and treat patients when the epidemic hits Norway with full force.

Sales of oseltamivir in Norway prior to the emergence of oseltamivir resistant influenza A(H1N1) viruses in 2007-08.

BACKGROUND: An unprecedented high proportion of oseltamivir resistant influenza A(H1N1) viruses emerged in the 2007-08 influenza season. In Norway, two thirds of all tested A(H1N1) viruses were resistant to the antiviral drug. In order to see if this emergence could be explained by a drug induced selection pressure, we analysed data on the sales of oseltamivir in Norway for the years 2002-07. METHODS: We used data from two sources; the Norwegian Drug Wholesales Statistics Database and the Norwegian Prescription Database (NorPD), for the years 2002-2007. We calculated courses sold of oseltamivir (Tamiflu) per 1000 inhabitants per year. RESULTS: Our data showed that, except for the years 2005 and 2006, sales of oseltamivir were low in Norway; courses sold per 1000 inhabitants varied between 0.17-1.64. The higher sales in 2005 and 2006 we believe were caused by private stockpiling in fear of a pandemic, and do not represent actual usage. CONCLUSION: A drug induced selection pressure was probably not the cause of the emergence of oseltamivir resistant influenza A(H1N1) viruses in 2007-08 in Norway.

The epidemiology of gonorrhoea in Norway, 1993-2007: past victories, future challenges.

BACKGROUND: Gonorrhoea, a bacterial infection caused by Neisseria gonorrhoeae, has been increasing in several European countries, particularly among men who have sex with men (MSM) and teenagers. We describe the epidemiology of gonorrhoea in Norway in the recent 15 years in order to guide recommendations on the diagnosis, treatment and prevention of gonorrhoea. An evaluation of the Norwegian Surveillance System for Communicable Diseases (MSIS) in 1994, involving GPs and microbiological laboratories, suggested that the system has a high coverage, capturing over 90% of patients diagnosed with gonorrhoea. METHODS: Using MSIS data on gonorrhoea cases we analysed specific trends by route of transmission, age, gender, anatomical sampling site, antimicrobial resistance and travel history from 1993-2007 and, to focus on more recent trends, from 2003-2007. MSM and heterosexual cases were defined by route of transmission. RESULTS: From 1993 to 2007, 3601 gonorrhoea cases were reported. MSM cases increased from 10 in 1994 to 109 cases in 2004. From 2003-2007, the incidence of gonorrhoea was 5.4/100,000 person-years (95%CI: 4.9-6.0). Over these five years, MSM accounted for an average of 80 cases per year, of which 69% were infected by casual partners. In the same period, 98% of heterosexually infected had a positive swab from urethra only and only two (0.3%) from the pharynx. Only one woman (0.5%) was positive from the rectum. From 1993 - 2007, antimicrobial resistance results were reported for 3325 N. gonorrhoeae isolates (98% of cultured samples). The proportion resistant to quinolone has risen from 3% in 1995 to 47% in 2007, with 81% of the latter isolated from patients infected in Asia. CONCLUSION: The overall incidence of gonorrhoea in Norway remains low, but the increasing number of MSM cases calls for new, more effective approaches to prevention. Infections originating from abroad represent a constant risk of importing antimicrobial resistant N. gonorrhoeae. Due to the prevalence of quinolone resistant N. gonorrhoeae in Norway, third-generation cephalosporins should replace quinolones as the first choice in treatment guidelines. We advocate antimicrobial susceptibility testing for all cases and recommend taking samples for culture from all exposed anatomical sites.

Oseltamivir-resistant influenza viruses A (H1N1), Norway, 2007-08.

In Norway in January 2008, unprecedented levels of oseltamivir resistance were found in 12 of 16 influenza viruses A (H1N1) tested. To investigate the epidemiologic and clinical characteristics of these viruses, we used sequence analysis to test all available subtype H1N1 viruses from the 2007-08 season for resistance. Questionnaires from physicians provided information on predisposing diseases, oseltamivir use, symptoms, and complications. Clinical data were obtained for 265 patients. In total, 183 (67.3%) of 272 viruses were oseltamivir resistant. Resistance was not associated with prior use of antiviral drugs. Symptoms and hospitalization rates did not differ for patients infected with a resistant or a susceptible virus. Oseltamivir-resistant influenza viruses A (H1N1) did not show diminished capability to spread in the absence of selective pressure. The ability of these viruses to sustain their fitness and spread among persons should be considered when shaping future strategies for treating and preventing seasonal and pandemic influenza.

A large waterborne outbreak of campylobacteriosis in Norway: the need to focus on distribution system safety.

BACKGROUND: On 7 May 2007 the medical officer in Røros (population 5600) reported 15 patients with gastroenteritis. Three days later he estimated hundreds being ill. Untreated tap water from a groundwater source was suspected as the vehicle and chlorination was started 11 May. Campylobacter was isolated from patients' stool samples. We conducted an investigation to identify the source and describe the extent of the outbreak. METHODS: We undertook a retrospective cohort study among a random sample of customers of Røros and neighbouring Holtålen waterworks. Holtålen, which has a different water source, was used as a control city. We conducted telephone interviews to gather data on illness from all household members. One randomly selected household member was asked about detailed exposure history. The regional hospital laboratory tested patients' stools for enteropathogens. Campylobacter isolates were typed by AFLP for genetic similarity at the Norwegian Institute of Public Health. Local authorities conducted the environmental investigation. RESULTS: We identified 105 cases among 340 individuals from Røros and Holtålen (Attack Rate = 31%). Tap water consumption was the only exposure associated with illness. Among randomly selected household members from Røros, a dose-response relationship was observed in daily consumed glasses of tap water (chi2 for trend = 8.1, p = 0.004). Campylobacter with identical AFLP was isolated from 25 out of 26 submitted stool samples. No pathogens were detected in water samples. We identified several events that might have caused pressure fall and influx of contaminated water into the water distribution system. On two occasions, pressure fall was noticed and parts of the distribution system were outdated. CONCLUSION: The investigation confirmed a waterborne outbreak of campylobacteriosis in Røros. Although no single event was identified as the cause of contamination, this outbreak illustrates the vulnerability of water distribution systems. Good quality source water alone is not enough to ensure water safety. For a better risk management, more focus should be put on the distribution system security. Waterworks personnel should monitor the pressure regularly; reduce the leakage by upgrading the distribution network and use chlorination when conducting maintenance work.

Non-travel related Hepatitis E virus genotype 3 infections in the Netherlands; a case series 2004 - 2006.

BACKGROUND: Human hepatitis E virus (HEV) infections are considered an emerging disease in industrialized countries. In the Netherlands, Hepatitis E virus (HEV) infections have been associated with travel to high-endemic countries. Non-travel related HEV of genotype 3 has been diagnosed occasionally since 2000. A high homology of HEV from humans and pigs suggests zoonotic transmission but direct molecular and epidemiological links have yet to be established. We conducted a descriptive case series to generate hypotheses about possible risk factors for non-travel related HEV infections and to map the genetic diversity of HEV. METHODS: A case was defined as a person with HEV infection laboratory confirmed (positive HEV RT-PCR and/or HEV IgM) after 1 January 2004, without travel to a high-endemic country three months prior to onset of illness. For virus identification 148 bp of ORF2 was sequenced and compared with HEV from humans and pigs. We interviewed cases face to face using a structured questionnaire and collected information on clinical and medical history, food preferences, animal and water contact. RESULTS: We interviewed 19 cases; 17 were male, median age 50 years (25-84 y), 12 lived in the North-East of the Netherlands and 11 had preexisting disease. Most common symptoms were dark urine (n = 16) and icterus (n = 15). Sixteen ate pork >/= once/week and six owned dogs. Two cases had received blood transfusions in the incubation period. Seventeen cases were viremic (genotype 3 HEV), two had identical HEV sequences but no identified relation. For one case, HEV with identical sequence was identified from serum and surface water nearby his home. CONCLUSION: The results show that the modes of transmission of genotype-3 HEV infections in the Netherlands remains to be resolved and that host susceptibility may play an important role in development of disease.

A novel putative enterococcal pathogenicity island linked to the esp virulence gene of Enterococcus faecium and associated with epidemicity.

Enterococcus faecalis harbors a virulence-associated surface protein encoded by the esp gene. This gene has been shown to be part of a 150-kb putative pathogenicity island. A gene similar to esp has recently been found in Enterococcus faecium isolates recovered from hospitalized patients. In the present study we analyzed the polymorphism in the esp gene of E. faecium, and we investigated the association of esp with neighboring chromosomal genes. The esp gene showed considerable sequence heterogeneity in the regions encoding the nonrepeat N- and C-terminal domains of the Esp protein as well as differences in the number of repeats. DNA sequencing of chromosomal regions flanking the esp gene of E. faecium revealed seven open reading frames, representing putative genes implicated in virulence, regulation of transcription, and antibiotic resistance. These flanking regions were invariably associated with the presence or absence of the esp gene in E. faecium, indicating that esp in E. faecium is part of a distinct genetic element. Because of the presence of virulence genes in this gene cluster, the lower G+C content relative to that of the genome, and the presence of esp in E. faecium isolates associated with nosocomial outbreaks and clinically documented infections, we conclude that this genetic element constitutes a putative pathogenicity island, the first one described in E. faecium. Except for the presence of esp and araC, this pathogenicity island is completely different from the esp-containing pathogenicity island previously disclosed in E. faecalis.

Vancomycin-resistant Enterococcus faecium (VREF) from Norwegian poultry cluster with VREF from poultry from the United Kingdom and The Netherlands in an amplified fragment length polymorphism genogroup.

The genetic relationship between 197 vancomycin-resistant Enterococcus faecium (VREF) isolates and 21 vancomycin-susceptible E. faecium isolates from Norwegian poultry was analyzed by amplified fragment length polymorphism (AFLP). The isolates were compared to 255 VREF isolates from various sources and countries. The Norwegian isolates constituted a relatively homogeneous population of E. faecium and clustered in a previously defined poultry AFLP genogroup.

Genetic linkage between erm(B) and vanA in Enterococcus hirae of poultry origin.

Vancomycin-resistant enterococci (VRE) have frequently been isolated from Norwegian poultry production following the prohibition of the glycopeptide growth promoter avoparcin since 1995. In the present study, a close genetic linkage between the vanA and erm(B) determinants in an Enterococcus hirae isolate of poultry origin is demonstrated, a result that indicates a mechanism for co-selection and maintenance of vancomycin resistance in absence of selective pressure from avoparcin. A total of 36 vanA-positive enterococci of poultry origin, also phenotypically resistant to erythromycin and/or tetracycline, were analyzed by PCR for identification of erm and tet resistance determinants. An E. hirae isolate harbored erm(B) and tet(K), and in this isolate vanA and erm(B) were located on a BamHI fragment of an approximately 50-kb plasmid. Approximately 3 kb of this fragment was amplified by PCR with vanA and erm(B) primers. Sequence analysis of the region between erm(B) and vanZ of Tn1546 showed a truncated IS1216V inserted downstream of the erm(B) stop codon, aligned with a conserved copy of the 3'-inverted terminal repeat of Tn1546. Mating experiments with the E. hirae isolate as donor and E. faecalis JH2-2 as recipient did not result in any transconjugants, indicating that the vanA/erm(B)-carrying plasmid was nonconjugative under the given experimental conditions.