• Age-specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study.

      Godefrooij, Daniel A; de Wit, G Ardine; Uiterwaal, Cuno S; Imhof, Saskia M; Wisse, Robert P L (2017-03)
      To determine the age-specific incidence and prevalence of keratoconus in the modern era of diagnostics.
    • Coxiella burnetii (Q fever) prevalence in associated populations of humans and small ruminants in The Gambia.

      Bok, Jeroen; Hogerwerf, Lenny; Germeraad, Eveline A; Roest, Hendrik I J; Faye-Joof, Tisbeh; Jeng, Momodou; Nwakanma, Davis; Secka, Arss; Stegeman, Arjan; Goossens, Bart; Wegmüller, Rita; van der Sande, Marianne A B; van der Hoek, Wim; Secka, Ousman (2017)
      To simultaneously estimate the prevalence of antibodies against Coxiella burnetii (Q fever) among adults and small ruminants, and C. burnetii shedding prevalence among small ruminants in households in the Kiang West district of The Gambia, and to assess associated risk factors.
    • Decreased, but still sufficient, iodine intake of children and adults in the Netherlands.

      Verkaik-Kloosterman, Janneke; Buurma-Rethans, Elly J M; Dekkers, Arnold L M; van Rossum, Caroline T M (2017-04)
      Sufficient I intake is important for the synthesis of thyroid hormones, which play an important role in normal growth and development. Our aim was to estimate habitual I intake for the Dutch population and the risk of inadequate or excessive intakes. Further, we aimed to provide an insight into the dietary sources of I and the association with socio-demographic factors. Data from the Dutch National Food Consumption Survey 2007-2010 (n 3819; 7-69 years), and from the Dutch food and supplement composition tables were used to estimate habitual I intake with a calculation model. Contribution of food groups to I intake were computed and multiple linear regression was used to examine associations of intakes with socio-demographic factors. A total of ≤2 % of the population had an intake below the estimated average requirement or above the upper level. The main sources of I were bread containing iodised salt (39 %), dairy products (14 %) and non-alcoholic drinks (6 %). I intake (natural sources only, excluding iodised salt and supplements) was positively associated with (parental) education, which could at least partly be attributed to a higher consumption of dairy products. Among children, the consumption of bread, often containing iodised bakery salt, was positively associated with parental education. The I intake of the Dutch population (7-69 years) seems adequate, although it has decreased since the period before 2008. With the current effort to reduce salt intake and changing dietary patterns (i.e. less bread, more organic foods) it is important to keep a close track on the I status, important sources and potential risk groups.
    • Distribution of serotypes and patterns of antimicrobial resistance among commensal Streptococcus pneumoniae in nine European countries.

      Yahiaoui, Rachid Y; Bootsma, Hester J; den Heijer, Casper D J; Pluister, Gerlinde N; John Paget, W; Spreeuwenberg, Peter; Trzcinski, Krzysztof; Stobberingh, Ellen E (2018-08-29)
      Streptococcus pneumoniae is a commensal of the human upper respiratory tract and a major cause of morbidity and mortality worldwide. This paper presents the distribution of serotypes and antimicrobial resistance in commensal S. pneumoniae strains cultured from healthy carriers older than four years of age in nine European countries.
    • Estimated incidence and number of outpatient visits for seasonal influenza in 2015-2016 in Beijing, China.

      Wu, S; Van Asten, L; Wang, L; McDonald, S A; Pan, Y; Duan, W; Zhang, L; Sun, Y; Zhang, Y; Zhang, X; Pilot, E; Krafft, T; Van Der Hoek, W; Van Der Sande, M A B; Yang, P; Wang, Q (2017)
      Information on morbidity burden of seasonal influenza in China is limited. A multiplier model was used to estimate the incidence and number of outpatient visits for seasonal influenza by age group for the 2015-2016 season in Beijing, the capital of China, based on reported numbers of influenza-like illness consultations and proportions of positive cases from influenza surveillance systems in Beijing, general consultation rates and other parameters from previous studies, surveys and surveillance systems. An estimated total of 1 190 200 (95% confidence interval (CI) 830 400-1 549 900) cases of influenza virus infections occurred in Beijing, 2015-2016 season, with an attack rate of 5·5% (95% CI 3·9-7·2%). These infections resulted in an estimated 468 280 (95% CI 70 700-606 800) outpatient visits, with an attack rate of 2·2% (95% CI 0·3-2·8%). The attack rate of influenza virus infections was highest among children aged 0-4 years (31·9% (95% CI 21·9-41·9%)), followed by children aged 5-14 years (18·7% (95% CI 12·9-24·5%)). Our study demonstrated a substantial influenza-related morbidity in Beijing, China, especially among the preschool- and school-aged children. This suggests that development or modification of seasonal influenza targeted vaccination strategies need to recognize that incidence is highest in children.
    • Estimation of age-specific rates of reactivation and immune boosting of the varicella zoster virus.

      Marinelli, Isabella; van Lier, Alies; de Melker, Hester; Pugliese, Andrea; van Boven, Michiel (2017)
      Studies into the impact of vaccination against the varicella zoster virus (VZV) have increasingly focused on herpes zoster (HZ), which is believed to be increasing in vaccinated populations with decreasing infection pressure. This idea can be traced back to Hope-Simpson's hypothesis, in which a person's immune status determines the likelihood that he/she will develop HZ. Immunity decreases over time, and can be boosted by contact with a person experiencing varicella (exogenous boosting) or by a reactivation attempt of the virus (endogenous boosting). Here we use transmission models to estimate age-specific rates of reactivation and immune boosting, exogenous as well as endogenous, using zoster incidence data from the Netherlands (2002-2011, n=7026). The boosting and reactivation rates are estimated with splines, enabling these quantities to be optimally informed by the data. The analyses show that models with high levels of exogenous boosting and estimated or zero endogenous boosting, constant rate of loss of immunity, and reactivation rate increasing with age (to more than 5% per year in the elderly) give the best fit to the data. Estimates of the rates of immune boosting and reactivation are strongly correlated. This has important implications as these parameters determine the fraction of the population with waned immunity. We conclude that independent evidence on rates of immune boosting and reactivation in persons with waned immunity are needed to robustly predict the impact of varicella vaccination on the incidence of HZ.
    • Excess all-cause and influenza-attributable mortality in Europe, December 2016 to February 2017.

      Vestergaard, Lasse S; Nielsen, Jens; Krause, Tyra G; Espenhain, Laura; Tersago, Katrien; Bustos Sierra, Natalia; Denissov, Gleb; Innos, Kaire; Virtanen, Mikko J; Fouillet, Anne; Lytras, Theodore; Paldy, Anna; Bobvos, Janos; Domegan, Lisa; O'Donnell, Joan; Scortichini, Matteo; de Martino, Annamaria; England, Kathleen; Calleja, Neville; van Asten, Liselotte; Teirlinck, Anne C; Tønnessen, Ragnhild; White, Richard A; P Silva, Susana; Rodrigues, Ana P; Larrauri, Amparo; Leon, Inmaculada; Farah, Ahmed; Junker, Christoph; Sinnathamby, Mary; Pebody, Richard G; Reynolds, Arlene; Bishop, Jennifer; Gross, Diane; Adlhoch, Cornelia; Penttinen, Pasi; Mølbak, Kåre (2017-04-06)
      Since December 2016, excess all-cause mortality was observed in many European countries, especially among people aged ≥ 65 years. We estimated all-cause and influenza-attributable mortality in 19 European countries/regions. Excess mortality was primarily explained by circulation of influenza virus A(H3N2). Cold weather snaps contributed in some countries. The pattern was similar to the last major influenza A(H3N2) season in 2014/15 in Europe, although starting earlier in line with the early influenza season start.
    • Frequency and determinants of consistent STI/HIV testing among men who have sex with men testing at STI outpatient clinics in the Netherlands: a longitudinal study.

      Visser, Maartje; Heijne, Janneke C M; Hogewoning, Arjan A; van Aar, Fleur (2017)
      Men who have sex with men (MSM) are at highest risk for STIs and HIV infections in the Netherlands. However, official guidelines on STI testing among MSM are lacking. They are advised to test for STIs at least every six months, but their testing behaviour is not well known. This study aimed to get insight into the proportion and determinants of consistent 6-monthly STI testing among MSM testing at STI outpatient clinics in the Netherlands.
    • Gender asymmetry in concurrent partnerships and HIV prevalence.

      Leung, Ka Yin; Powers, Kimberly A; Kretzschmar, Mirjam (2017)
      The structure of the sexual network of a population plays an essential role in the transmission of HIV. Concurrent partnerships, i.e. partnerships that overlap in time, are important in determining this network structure. Men and women may differ in their concurrent behavior, e.g. in the case of polygyny where women are monogamous while men may have concurrent partnerships. Polygyny has been shown empirically to be negatively associated with HIV prevalence, but the epidemiological impacts of other forms of gender-asymmetric concurrency have not been formally explored. Here we investigate how gender asymmetry in concurrency, including polygyny, can affect the disease dynamics. We use a model for a dynamic network where individuals may have concurrent partners. The maximum possible number of simultaneous partnerships can differ for men and women, e.g. in the case of polygyny. We control for mean partnership duration, mean lifetime number of partners, mean degree, and sexually active lifespan. We assess the effects of gender asymmetry in concurrency on two epidemic phase quantities (R0 and the contribution of the acute HIV stage to R0) and on the endemic HIV prevalence. We find that gender asymmetry in concurrent partnerships is associated with lower levels of all three epidemiological quantities, especially in the polygynous case. This effect on disease transmission can be attributed to changes in network structure, where increasing asymmetry leads to decreasing network connectivity.
    • Heterosubtypic cross-reactivity of HA1 antibodies to influenza A, with emphasis on nonhuman subtypes (H5N1, H7N7, H9N2).

      Te Beest, Dennis E; de Bruin, Erwin; Imholz, Sandra; Koopmans, Marion; van Boven, Michiel (2017)
      Epidemics of influenza A vary greatly in size and age distribution of cases, and this variation is attributed to varying levels of pre-existing immunity. Recent studies have shown that antibody-mediated immune responses are more cross-reactive than previously believed, and shape patterns of humoral immunity to influenza A viruses over long periods. Here we quantify antibody responses to the hemagglutinin subunit 1 (HA1) across a range of subtypes using protein microarray analysis of cross-sectional serological surveys carried out in the Netherlands before and after the A/2009 (H1N1) pandemic. We find significant associations of responses, both within and between subtypes. Interestingly, substantial overall reactivity is observed to HA1 of avian H7N7 and H9N2 viruses. Seroprevalence of H7N7 correlates with antibody titers to A/1968 (H3N2), and is highest in persons born between 1954 and 1969. Seroprevalence of H9N2 is high across all ages, and correlates strongly with A/1957 (H2N2). This correlation is most pronounced in A/2009 (H1N1) infected persons born after 1968 who have never encountered A/1957 (H2N2)-like viruses. We conclude that heterosubtypic antibody cross-reactivity, both between human subtypes and between human and nonhuman subtypes, is common in the human population.
    • HIV testing week 2015: lowering barriers for HIV testing among high-risk groups in Amsterdam.

      Bartelsman, M; Joore, I K; van Bergen, J E; Hogewoning, A A; Zuure, F R; van Veen, M G (2017-08-01)
      Evaluation of the HIV Testing Week (HTW) 2015 in Amsterdam: the number of (positive) tested persons, characteristics and testing history of the tested population, the differences in attendance per location and the healthcare workers' experiences and opinions concerning the HTW.
    • Identification of differences in health impact modelling of salt reduction.

      Hendriksen, Marieke A H; Geleijnse, Johanna M; van Raaij, Joop M A; Cappuccio, Francesco P; Cobiac, Linda C; Scarborough, Peter; Nusselder, Wilma J; Jaccard, Abbygail; Boshuizen, Hendriek C (2017)
      We examined whether specific input data and assumptions explain outcome differences in otherwise comparable health impact assessment models. Seven population health models estimating the impact of salt reduction on morbidity and mortality in western populations were compared on four sets of key features, their underlying assumptions and input data. Next, assumptions and input data were varied one by one in a default approach (the DYNAMO-HIA model) to examine how it influences the estimated health impact. Major differences in outcome were related to the size and shape of the dose-response relation between salt and blood pressure and blood pressure and disease. Modifying the effect sizes in the salt to health association resulted in the largest change in health impact estimates (33% lower), whereas other changes had less influence. Differences in health impact assessment model structure and input data may affect the health impact estimate. Therefore, clearly defined assumptions and transparent reporting for different models is crucial. However, the estimated impact of salt reduction was substantial in all of the models used, emphasizing the need for public health actions.
    • Immune Responses After 2 Versus 3 Doses of HPV Vaccination up to 4½ Years After Vaccination: An Observational Study Among Dutch Routinely Vaccinated Girls.

      Donken, Robine; Schurink-Van't Klooster, Tessa M; Schepp, Rutger M; van der Klis, Fiona R M; Knol, Mirjam J; Meijer, Chris J L M; de Melker, Hester E (2017-02-01)
      In 2014 the Netherlands switched from 3 to 2 doses for routine vaccination with the prophylactic bivalent human papillomavirus (HPV) vaccine. The current study explored whether antibody responses are noninferior after 2 versus 3 doses in girls.
    • The impact of ambient air pollution on the human blood metabolome.

      Vlaanderen, J J; Janssen, N A; Hoek, G; Keski-Rahkonen, P; Barupal, D K; Cassee, F R; Gosens, I; Strak, M; Steenhof, M; Lan, Q; Brunekreef, B; Scalbert, A; Vermeulen, R C H (2017-07)
      Biological perturbations caused by air pollution might be reflected in the compounds present in blood originating from air pollutants and endogenous metabolites influenced by air pollution (defined here as part of the blood metabolome). We aimed to assess the perturbation of the blood metabolome in response to short term exposure to air pollution.
    • Impact of Survey Administration Mode on the Results of a Health-Related Discrete Choice Experiment: Online and Paper Comparison.

      Determann, Domino; Lambooij, Mattijs S; Steyerberg, Ewout W; de Bekker-Grob, Esther W; de Wit, G Ardine (2018-01-04)
      Electronic data collection is increasingly being used for discrete choice experiments (DCEs).
    • The impact of urban regeneration programmes on health and health-related behaviour: Evaluation of the Dutch District Approach 6.5 years from the start.

      Ruijsbroek, Annemarie; Wong, Albert; Kunst, Anton E; van den Brink, Carolien; van Oers, Hans A M; Droomers, Mariël; Stronks, Karien (2017)
      Large-scale regeneration programmes to improve the personal conditions and living circumstances in deprived areas may affect health and the lifestyle of the residents. Previous evaluations concluded that a large-scale urban regeneration programme in the Netherlands had some positive effects within 3.5 years. The aim of the current study was to evaluate the effects at the longer run.
    • Infectious reactivation of cytomegalovirus explaining age- and sex-specific patterns of seroprevalence.

      van Boven, Michiel; van de Kassteele, Jan; Korndewal, Marjolein J; van Dorp, Christiaan H; Kretzschmar, Mirjam; van der Klis, Fiona; de Melker, Hester E; Vossen, Ann C; van Baarle, Debbie (2017-09)
      Human cytomegalovirus (CMV) is a herpes virus with poorly understood transmission dynamics. Person-to-person transmission is thought to occur primarily through transfer of saliva or urine, but no quantitative estimates are available for the contribution of different infection routes. Using data from a large population-based serological study (n = 5,179), we provide quantitative estimates of key epidemiological parameters, including the transmissibility of primary infection, reactivation, and re-infection. Mixture models are fitted to age- and sex-specific antibody response data from the Netherlands, showing that the data can be described by a model with three distributions of antibody measurements, i.e. uninfected, infected, and infected with increased antibody concentration. Estimates of seroprevalence increase gradually with age, such that at 80 years 73% (95%CrI: 64%-78%) of females and 62% (95%CrI: 55%-68%) of males are infected, while 57% (95%CrI: 47%-67%) of females and 37% (95%CrI: 28%-46%) of males have increased antibody concentration. Merging the statistical analyses with transmission models, we find that models with infectious reactivation (i.e. reactivation that can lead to the virus being transmitted to a novel host) fit the data significantly better than models without infectious reactivation. Estimated reactivation rates increase from low values in children to 2%-4% per year in women older than 50 years. The results advance a hypothesis in which transmission from adults after infectious reactivation is a key driver of transmission. We discuss the implications for control strategies aimed at reducing CMV infection in vulnerable groups.
    • Influenza vaccine effectiveness estimates in the Dutch population from 2003 to 2014: The test-negative design case-control study with different control groups.

      van Doorn, Eva; Darvishian, Maryam; Dijkstra, Frederika; Donker, Gé A; Overduin, Pieter; Meijer, Adam; Hak, Eelko (2017-05-15)
      Information about influenza vaccine effectiveness (IVE) is important for vaccine strain selection and immunization policy decisions. The test-negative design (TND) case-control study is commonly used to obtain IVE estimates. However, the definition of the control patients may influence IVE estimates. We have conducted a TND study using the Dutch Sentinel Practices of NIVEL Primary Care Database which includes data from patients who consulted the General Practitioner (GP) for an episode of acute influenza-like illness (ILI) or acute respiratory infection (ARI) with known influenza vaccination status. Cases were patients tested positive for influenza virus. Controls were grouped into those who tested (1) negative for influenza virus (all influenza negative), (2) negative for influenza virus, but positive for respiratory syncytial virus, rhinovirus or enterovirus (non-influenza virus positive), and (3) negative for these four viruses (pan-negative). We estimated the IVE over all epidemic seasons from 2003/2004 through 2013/2014, pooled IVE for influenza vaccine partial/full matched and mismatched seasons and the individual seasons using generalized linear mixed-effect and multiple logistic regression models. The overall IVE adjusted for age, GP ILI/ARI diagnosis, chronic disease and respiratory allergy was 35% (95% CI: 15-48), 64% (95% CI: 49-75) and 21% (95% CI: -1 to 39) for all influenza negative, non-influenza virus positive and pan-negative controls, respectively. In both the main and subgroup analyses IVE estimates were the highest using non-influenza virus positive controls, likely due to limiting inclusion of controls without laboratory-confirmation of a virus causing the respiratory disease.
    • Outbreak of diarrhoea among participants of a triathlon and a duathlon on 12 July 2015 in Utrecht, the Netherlands.

      Parkkali, S; Joosten, R; Fanoy, E; Pijnacker, R; VAN Beek, J; Brandwagt, D; VAN Pelt, W (2017-07)
      On 12 July 2015, a triathlon competition with 900 participants took place in Utrecht, the Netherlands. An outbreak investigation was initiated after 56 participants reported health complaints. An online questionnaire was sent to 700 participants. Stool specimens from six participants and four water specimens were collected from the swimming location. A total of 239 participants completed the questionnaire (response rate: 34%), 73 (31%) of them met the case definition for acute gastrointestinal illness (AGI). A total of 67% of the respondents were male and the median age was 38 years. Almost half (42%) of swimmers reported health complaints. Consumption of energy drinks and ingesting ⩾3 mouthfuls of canal water were identified as risk factors for AGI among swimmers only (adjusted relative risks (aRR) 1·6; 95% confidence intervals (CI) 1·0-2·5 and aRR 2·6; 95% CI 1·5-4·8). The collected water specimens tested positive for norovirus genogroup I and rotavirus and stool specimens tested positive for norovirus genogroup II. Our findings indicate that the outbreak could have been caused by exposure to norovirus during swimming. Swimmers should get information about the health risks for making an informed choice about participating. For future events, the organisers decided to change the swimming location from a canal to a recreational lake.
    • Pubertal Timing and Cardiometabolic Markers at Age 16 Years.

      Berentzen, Nina E; Wijga, Alet H; van Rossem, Lenie; Postma, Dirkje S; Gehring, Ulrike; Smit, Henriëtte A (2017-08)
      To examine the association between pubertal timing and cardiometabolic markers among adolescents.