Severe acute respiratory infections surveillance for early signals in the community.

BACKGROUND: Surveillance of acute respiratory infections (ARI) in the Netherlands and other European countries is based mostly on primary care data, with little insight into the severe spectrum of the disease. We compared time-trends for ARI in secondary care with influenza-like illness (ILI), ARI and pneumonia in primary care, and crude mortality, in order to assess the value of routinely collected data on respiratory infections in hospitals and the added value of severe acute respiratory infections (SARI) surveillance. METHODS: We calculated incidence of ARI in secondary care, ILI, ARI, and pneumonia in primary care, and crude mortality using five historical databases (2008-2016). RESULTS: Over eight years, seasonal incidence peaks of ARI in secondary care occurred earlier than ILI and ARI incidence peaks in primary care, except during the 2009 influenza A(H1N1) pandemic and post-pandemic season. The median time-lag between ARI in secondary care and ILI, ARI and pneumonia in primary care was 6.5 weeks, 7 weeks, and 1 week, respectively. Crude mortality lagged a median 5 weeks behind ARI in secondary care. CONCLUSION: This observational study demonstrates that routinely collected data can be used for describing trends of ARI in secondary care and may be suitable for near real-time SARI surveillance. In most seasons, the incidence peaks for ARI in secondary care preceded the peaks in primary care and crude mortality with a considerable time-lag. It would be of great value to add microbiological test results to the incidence data to better explain the difference in time-lag between these surveillance systems.

Notification data and criteria during a large Q-fever epidemic reassessed.

From 2007 to 2010, the largest reported Q-fever epidemic occurred in the Netherlands with 4026 notified laboratory-confirmed cases. During the course of the epidemic, health-seeking behaviour changed and awareness among health professionals increased. Changes in laboratory workflows were implemented. The aim of this study was to analyse how these changes instigated adjustments of notification criteria and how these adjustments affected the monitoring and interpretation of the epidemic. We used the articles on laboratory procedures related to the epidemic and a description of the changes that were made to the notification criteria. We compared the output of a regional laboratory with notifications to the regional Public Health Service and the national register of infectious diseases. We compared the international notification criteria for acute Q-fever. Screening with ELISA IgM phase II and PCR was added to the diagnostic workflow. In the course of the epidemic, serology often revealed a positive IgG/IgM result although cases were not infected recently. With increasing background seroprevalence, the presence of IgM antibodies can only be suggestive for acute Q-fever and has to be confirmed either by seroconversion of IgG or a positive PCR result. Differences in sero-epidemiology make it unlikely that full harmonisation of notification criteria between countries is feasible.

[Effectiveness of influenza vaccine in the Netherlands: predominant circulating virus type and vaccine match are important conditions]. / Effectiviteit van influenzavaccinatie in Nederland.

OBJECTIVE: To investigate the relationship between circulating influenza virus A types and subtypes and influenza B lineages, their match with the vaccine and the effectiveness of the influenza vaccine (IVE). DESIGN: Test negative case control study. METHOD: We used data from the Dutch Sentinel Practices of the Netherlands Institute for Health Services Research (NIVEL) Primary Care Database. Participating general practitioners took nose and throat swabs for viral studies from patients with influenza-like illness or another acute respiratory infection. Cases were those patients whose samples were positive for an influenza virus and controls were those whose samples were negative for influenza virus. We determined the IVE of 11 influenza seasons 2003/2004 to 2013/2014, for all seasons together and stratified by influenza virus type and to vaccine match or mismatch. RESULTS: Over all seasons, the IVE was 29% (95% CI:11-43). In seven of the 11 seasons there was a mismatch between vaccine and circulating virus type. The IVE was 40% (95% CI: 18-56) for those seasons in which there was a vaccine match, and 20% (95% CI: - 5-38) for seasons with a mismatch. When the influenza A/H3N2 virus was dominant, the IVE was 38% (95% CI: 14-55). The IVE against the influenza virus A/H1N1, A/H1N1/pdm09 and against both influenza B lineages was 77% (95% CI: 37-92), 47% (95% CI: 22-64) and 64% (95% CI: 50-74), respectively. CONCLUSION: The IVE was particularly low when there was a mismatch between the vaccine and the circulating virus type and when A/H3N2 was the dominant influenza subtype.

Coxiella burnetii seroprevalence and risk factors on commercial sheep farms in The Netherlands.

Coxiella burnetii seroprevalence was assessed on Dutch dairy and non-dairy sheep farms using ELISA. Risk factors for seropositivity on non-dairy sheep farms were identified at farm and sheep level by univariate and multivariate multilevel analyses. Based on 953 dairy and 5671 non-dairy serum samples, sheep seroprevalences were 18.7 per cent and 2.0 per cent, respectively, and 78.6 per cent and 30.5 per cent at farm level. Significant risk factors for non-dairy sheep farms were farm location in the south of the country, sheep kept on marginal grounds, one or several supply addresses for ewes during 2007-2009 and wearing farm boots and/or outfit by professional visitors. On sheep level, risk factors included among others farm location in the south of the country, lamb breeding as main farm purpose, goat density within 10 km farm radius, use of windbreak curtain or windshields, and presence of ≥6 stillborn lambs in 2009. Farm location in the south of the country and goat density suggests that infected goats have played a role in the transmission to non-dairy sheep. Other risk factors suggest introduction of the bacterium through sheep supply and professional visitors. Biosecurity measures should be strengthened, including avoiding infection during handling of stillborn lambs and birth products in the lambing period.

Coxiella burnetii seroprevalence and risk factors in sheep farmers and farm residents in The Netherlands.

SUMMARY: In this study, Coxiella burnetii seroprevalence was assessed for dairy and non-dairy sheep farm residents in The Netherlands for 2009-2010. Risk factors for seropositivity were identified for non-dairy sheep farm residents. Participants completed farm-based and individual questionnaires. In addition, participants were tested for IgG and IgM C. burnetii antibodies using immunofluorescent assay. Risk factors were identified by univariate, multivariate logistic regression, and multivariate multilevel analyses. In dairy and non-dairy sheep farm residents, seroprevalence was 66·7% and 51·3%, respectively. Significant risk factors were cattle contact, high goat density near the farm, sheep supplied from two provinces, high frequency of refreshing stable bedding, farm started before 1990 and presence of the Blessumer breed. Most risk factors indicate current or past goat and cattle exposure, with limited factors involving sheep. Subtyping human, cattle, goat, and sheep C. burnetii strains might elucidate their role in the infection risk of sheep farm residents.