Childhood infections and common carotid intima media thickness in adolescence.

Atherosclerotic changes can be measured as changes in common carotid intima media thickness (CIMT). It is hypothesised that repeated infection-associated inflammatory responses in childhood contribute to the atherosclerotic process. We set out to determine whether the frequency of infectious diseases in childhood is associated with CIMT in adolescence. The study is part of the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) population-based birth cohort. At age 16 years, common CIMT was measured. We collected general practitioner (GP) diagnosed infections and prescribed antibiotics. Parent-reported infections were retrieved from annual questionnaires. Linear regression analysis assessed the association between number of infections during the first 4 years of life and common CIMT. Common CIMT measurement, GP and questionnaire data were available for 221 participants. No association was observed between the infection measures and CIMT. In a subgroup analysis, significant positive associations with CIMT were observed in participants with low parental education for 2-3 or ⩾7 GP diagnosed infections (+26.4 µm, 95% CI 0.4-52.4 and +26.8 µm, 95% CI 3.6-49.9, respectively) and ⩾3 antibiotic prescriptions (+35.5 µm, 95%CI 15.8-55.3). Overall, early childhood infections were not associated with common CIMT in adolescence. However, a higher number of childhood infections might contribute to the inflammatory process of atherosclerosis in subgroups with low education, this needs to be confirmed in future studies.

Outbreaks of syphilis among men who have sex with men attending STI clinics between 2007 and 2015 in the Netherlands: a space-time clustering study.

OBJECTIVES: Infectious syphilis (syphilis) is diagnosed predominantly among men who have sex with men (MSM) in the Netherlands and is a strong indicator for sexual risk behaviour. Therefore, an increase in syphilis can be an early indicator of resurgence of other STIs, including HIV. National and worldwide outbreaks of syphilis, as well as potential changes in sexual networks were reason to explore syphilis trends and clusters in more depth. METHODS: National STI/HIV surveillance data were used, containing epidemiological, behavioural and clinical data from STI clinics. We examined syphilis positivity rates stratified by HIV status and year. Additionally, we performed space-time cluster analysis on municipality level between 2007 and 2015, using SaTScan to evaluate whether or not there was a higher than expected syphilis incidence in a certain area and time period, using the maximum likelihood ratio test statistic. RESULTS: Among HIV-positive MSM, the syphilis positivity rate decreased between 2007 (12.3%) and 2011 (4.5%), followed by an increasing trend (2015: 8.0%). Among HIV-negative MSM, the positivity rate decreased between 2007 (2.8%) and 2011 also (1.4%) and started to increase from 2013 onwards (2015: 1.8%). In addition, we identified three geospatial clusters. The first cluster consisted of MSM sex workers in the South of the Netherlands (July 2009-September 2010, n=10, p<0.001). The second cluster were mostly HIV-positive MSM (58.5%) (Amsterdam; July 2011-December 2015; n=1123, p<0.001), although the proportion of HIV-negative MSM increased over time. The third cluster was large in space (predominantly the city of Rotterdam; April-September 2015, n=72, p=0.014) and were mostly HIV-negative MSM (62.5%). CONCLUSIONS: Using SaTScan analysis, we observed several not yet recognised outbreaks and a rapid resurgence of syphilis among known HIV-positive MSM first, but more recently, also among HIV-negative MSM. The three identified clusters revealed locations, periods and specific characteristics of the involved MSM that could be used when developing targeted interventions.

Estimated incidence and number of outpatient visits for seasonal influenza in 2015-2016 in Beijing, China.

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.

The Netherlands Chlamydia cohort study (NECCST) protocol to assess the risk of late complications following Chlamydia trachomatis infection in women.

BACKGROUND: Chlamydia trachomatis (CT), the most common bacterial sexually transmitted infection (STI) among young women, can result in serious sequelae. Although the course of infection is often asymptomatic, CT may cause pelvic inflammatory disease (PID), leading to severe complications, such as prolonged time to pregnancy, ectopic pregnancy, and tubal factor subfertility. The risk of and risk factors for complications following CT-infection have not been assessed in a long-term prospective cohort study, the preferred design to define infections and complications adequately. METHODS: In the Netherlands Chlamydia Cohort Study (NECCST), a cohort of women of reproductive age with and without a history of CT-infection is followed over a minimum of ten years to investigate (CT-related) reproductive tract complications. This study is a follow-up of the Chlamydia Screening Implementation (CSI) study, executed between 2008 and 2011 in the Netherlands. For NECCST, female CSI participants who consented to be approached for follow-up studies (n = 14,685) are invited, and prospectively followed until 2022. Four data collection moments are foreseen every two consecutive years. Questionnaire data and blood samples for CT-Immunoglobulin G (IgG) measurement are obtained as well as host DNA to determine specific genetic biomarkers related to susceptibility and severity of infection. CT-history will be based on CSI test outcomes, self-reported infections and CT-IgG presence. Information on (time to) pregnancies and the potential long-term complications (i.e. PID, ectopic pregnancy and (tubal factor) subfertility), will be acquired by questionnaires. Reported subfertility will be verified in medical registers. Occurrence of these late complications and prolonged time to pregnancy, as a proxy for reduced fertility due to a previous CT-infection, or other risk factors, will be investigated using longitudinal statistical procedures. DISCUSSION: In the proposed study, the occurrence of late complications following CT-infection and its risk factors will be assessed. Ultimately, provided reliable risk factors and/or markers can be identified for such late complications. This will contribute to the development of a prognostic tool to estimate the risk of CT-related complications at an early time point, enabling targeted prevention and care towards women at risk for late complications. TRIAL REGISTRATION: Dutch Trial Register NTR-5597 . Retrospectively registered 14 February 2016.

Young male sex workers are at high risk for sexually transmitted infections, a cross-sectional study from Dutch STI clinics, the Netherlands, 2006-2012.

BACKGROUND: Male sex workers (MSW) are particularly exposed to sexually transmitted infections (STI) including HIV. In the Netherlands, data about STI among MSW are scarce. We estimated chlamydia, gonorrhoea, syphilis and HIV diagnoses among MSW attending STI clinics and determined associated factors to guide prevention policies. METHODS: Using 2006-2012 cross-sectional national surveillance data from Dutch STI clinics, we calculated the proportion of consultations with a positive test for any of three bacterial STI or HIV among MSW. Associated factors were determined by using Poisson logistic regression with robust variance. RESULTS: We identified 3,053 consultations involving MSW, of which 18.1 % included at least one positive bacterial STI test and 2.5 % a positive HIV test. Factors associated with bacterial STI and/or HIV diagnoses were respectively age groups < 35 y.o. and self-reporting homo- or bisexual preferences (aRR = 1.6; 95 % CI: 1.3-2.1), and age group 25-34 y.o. (aRR = 2.7; 95 % CI: 1.2-6.5) and self-reporting homo- or bisexual preferences (aRR = 24.4; 95 % CI: 3.4-176.9). Newly diagnosed and pre-existing HIV infection were associated with an increased risk for bacterial STI (aRR = 2.7, 95 % CI: 1.7-2.6 and aRR = 2.1, 95 % CI: 2.2-3.4 respectively). MSW with no history of HIV screening were more likely to be tested positive for HIV compared to those with a previous HIV-negative test (aRR = 2.6, 95 % CI: 1.6-4.3). CONCLUSION: Health promotion activities should target MSW who are young, homo- or bisexual, those who are HIV-infected or who have never been tested for HIV, to increase early diagnosis, prevention and treatment.

Disease burden of congenital cytomegalovirus infection at school entry age: study design, participation rate and birth prevalence.

Congenital cytomegalovirus infection (cCMV) may lead to symptoms at birth and long-term consequences. We present a nationwide, retrospective cohort study on the outcome of cCMV up to age 6 years. For this study we identified cCMV, using polymerase chain reaction, by analysing dried blood spots, which are taken shortly after birth for neonatal screening. The group of children with cCMV were compared to a group of children who were cCMV negative at birth. Data were collected about their health and development up to age 6 years. Parents of 73 693 children were invited to participate, and 32 486 (44·1%) gave informed consent for testing of their child's dried blood spot for CMV. Of the 31 484 dried blood spots tested, 156 (0·5%) were positive for cCMV. Of these, four (2·6%) children had been diagnosed with cCMV prior to this study. This unique retrospective nationwide study permits the estimation of long-term sequelae of cCMV up to the age of 6 years. The birth prevalence of cCMV in this study was 0·5%, which is in line with prior estimates. Most (97·4%) children with cCMV had not been diagnosed earlier, indicating under-diagnosis of cCMV.

Delayed linkage to care in one-third of HIV-positive individuals in the Netherlands.

OBJECTIVES: To determine time to linkage to HIV care following diagnosis and to identify risk factors for delayed linkage. METHODS: Patients newly diagnosed with HIV at sexually transmitted infections (STI) clinics in the Netherlands were followed until linkage to care. Data were collected at the time of diagnosis and at first consultation in care, including demographics, behavioural information, CD4+ counts and HIV viral load (VL) measurements. Delayed linkage to care was defined as >4 weeks between HIV diagnosis and first consultation. RESULTS: 310 participants were included; the majority (90%) being men who have sex with men (MSM). For 259 participants (84%), a date of first consultation in care was known; median time to linkage was 9 days (range 0-435). Overall, 95 (31%) of the participants were not linked within 4 weeks of diagnosis; among them, 44 were linked late, and 51 were not linked at all by the end of study follow-up. Being young (<25 years), having non-Western ethnicity or lacking health insurance were independently associated with delayed linkage to care as well as being referred to care indirectly. Baseline CD4+ count, VL, perceived social support and stigma at diagnosis were not associated with delayed linkage. Risk behaviour and CD4+ counts declined between diagnosis and linkage to care. CONCLUSIONS: Although most newly diagnosed patients with HIV were linked to care within 4 weeks, delay was observed for one-third, with over half of them not yet linked at the end of follow-up. Vulnerable subpopulations (young, uninsured, ethnic minority) were at risk for delayed linkage. Testing those at risk is not sufficient, timely linkage to care needs to be better assured as well.

Public health measures to control the spread of antimicrobial resistance in Neisseria gonorrhoeae in men who have sex with men.

Gonorrhoea is one of the most common sexually transmitted infections. The control of gonorrhoea is extremely challenging because of the repeated development of resistance to the antibiotics used for its treatment. We explored different strategies to control the spread of antimicrobial resistance and prevent increases in gonorrhoea prevalence. We used a mathematical model that describes gonorrhoea transmission among men who have sex with men and distinguishes gonorrhoea strains sensitive or resistant to three antibiotics. We investigated the impact of combination therapy, switching first-line antibiotics according to resistance thresholds, and other control efforts (reduced sexual risk behaviour, increased treatment rate). Combination therapy can delay the spread of resistance better than using the 5% resistance threshold. Increased treatment rates, expected to enhance gonorrhoea control, may reduce gonorrhoea prevalence only in the short term, but could lead to more resistance and higher prevalence in the long term. Re-treatment of resistant cases with alternative antibiotics can substantially delay the spread of resistance. In conclusion, combination therapy and re-treatment of resistant cases with alternative antibiotics could be the most effective strategies to prevent increases in gonorrhoea prevalence due to antimicrobial resistance.

Chlamydia trachomatis IgG seroprevalence in the general population of the Netherlands in 1996 and in 2007: differential changes by gender and age.

OBJECTIVES: Chlamydia trachomatis (CT) reporting rates from sexually transmitted infection clinics and general practitioners have shown a rising trend in the Netherlands. It is unknown to what extent this reflects increased CT transmission or improved case finding. To achieve more insight into the CT epidemic, we explored the CT IgG seroprevalence (a marker of past CT infection) in the general population of the Netherlands in 1996 and in 2007. METHODS: From two population-based studies in 1996 and 2007, serum samples, demographic and sexual behaviour outcomes were examined, including 1246 men and 1930 women aged 15-39 years. Serum CT IgG antibodies were analysed using the Medac CT IgG ELISA test. Multivariate logistic regression analyses explored the seroprevalence and determinants over time. RESULTS: The CT IgG seroprevalence was higher in women than in men (10% vs 6%). Among women aged 25-39 years the seroprevalence was lower in 2007 (9%) than in 1996 (14%; adjusted OR (aOR) 0.6, 95% CI 0.4 to 0.8). There was no statistical evidence of a difference in seroprevalence within birth cohorts. Factors associated with seropositivity were male gender (aOR 0.4, 95% CI 0.3 to 0.7), a self-reported history of CT infection (aOR 5.1, 95% CI 2.6 to 10.0), age 25-39 years (aOR 1.7, 95% CI 1.1 to 2.7), non-Western ethnicity (aOR 2.2, 95% CI 1.4 to 3.3) and ≥ 2 recent sexual partners (aOR 2.2, 95% CI 1.3 to 3.5). CONCLUSIONS: Between 1996 and 2007 the proportion of individuals in the general population with CT IgG antibodies was lower among women aged 25-39 years, but remained similar among younger women and men.

The 2009 influenza A (H1N1) pandemic. Management and vaccination strategies in The Netherlands.

Prior to 2009, The Netherlands had prepared itself extensively for a potential pandemic. Multidisciplinary guidelines had been drafted to control transmission and limit adverse outcomes for both a phase of early incidental introduction and for a phase with widespread transmission. The Ministry of Health had ensured a supply and distribution schedule for antivirals and negotiated a contract for vaccine purchases. During the pandemic, existing surveillance was expanded, the established infectious disease response structure was activated, and the previously prepared protocols for communication, diagnostics, use of antivirals, and vaccination implementation were operationalized and implemented. When the pandemic turned out to be less severe than many had anticipated, risk communication and rapid modification of guidelines and communication became a major challenge. Antivirals and pandemic vaccines were reserved for those at high risk for severe outcomes only. Overall, the impact of the pandemic was comparable to the impact of an average seasonal influenza epidemic, but with a shift in (severe) outcomes from the very young and elderly toward young adults. Established prepared protocols enabled timely coordinated responses. In preparing for the worst, sufficient attention must be given to preparing for a mild scenario as well.

Comparing two definitions of ethnicity for identifying young persons at risk for chlamydia.

Ethnic disparities in chlamydia infections in The Netherlands were assessed, in order to compare two definitions of ethnicity: ethnicity based on country of birth and self-defined ethnicity. Chlamydia positivity in persons aged 16-29 years was investigated using data from the first round of the Chlamydia Screening Implementation (CSI, 2008-2009) and surveillance data from STI centres (2009). Logistic regression modelling showed that being an immigrant was associated with chlamydia positivity in both CSI [adjusted odds ratio (aOR) 2·3, 95% confidence interval (CI) 2·0-2·6] and STI centres (aOR 1·4, 95% CI 1·3-1·5). In both settings, 60% of immigrants defined themselves as Dutch. Despite the difference, classification by self-defined ethnicity resulted in similar associations between (non-Dutch) ethnicity and chlamydia positivity. However, ethnicity based on country of birth explained variation in chlamydia positivity better, and is objective and constant over time and therefore more useful for identifying young persons at higher risk for chlamydia infection.

Prevalence of hepatitis B virus infection in The Netherlands in 1996 and 2007.

We aimed to assess differences in the prevalence of hepatitis B virus (HBV) infection in The Netherlands between 1996 and 2007, and to identify risk factors for HBV infection in 2007. Representative samples of the Dutch population in 1996 and 2007 were tested for antibodies to hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg) and HBV-DNA. In 2007, the weighted anti-HBc prevalence was 3·5% (95% CI 2·2-5·5) and the HBsAg prevalence was 0·2% (95% CI 0·1-0·4). In indigenous Dutch participants, the anti-HBc prevalence was lower in 2007 than in 1996 (P=0·06). First-generation migrants (FGMs) had a 13-fold greater risk of being HBsAg- and/or HBV-DNA-positive than indigenous Dutch participants. In indigenous Dutch participants, risk factors for anti-HBc positivity were older age and having received a blood product before 1990. In FGMs, being of Asian origin was a risk factor. In second-generation migrants, having a foreign-born partner and injecting drug use were risk factors. FGMs are the main target group for secondary HBV prevention in The Netherlands.

The burden of 2009 pandemic influenza A(H1N1) in the Netherlands.

BACKGROUND: The disease burden of the 2009 influenza pandemic has been debated but reliable estimates are lacking. To guide future policy and control, these estimates are necessary. This study uses burden of disease measurements to assess the contribution of the pandemic influenza A(H1N1) virus to the overall burden of disease in the Netherlands. METHODS: The burden of disease caused by 2009 pandemic influenza was estimated by calculating Disability Adjusted Life Years (DALY), a composite measure that combines incidence, sequelae and mortality associated with a disease, taking duration and severity into account. Available influenza surveillance data sources (primary care sentinel surveillance, notification data on hospitalizations and deaths and death registries) were used. Besides a baseline scenario, five alternative scenarios were used to assess effects of changing values of input parameters. RESULTS: The baseline scenario showed a loss of 5800 DALY for the Netherlands (35 DALY per 100 000 population). This corresponds to 0.13% of the estimated annual disease burden in the Netherlands and is comparable to the estimated disease burden of seasonal influenza, despite a different age distribution in incidence and mortality of the pandemic compared to seasonal influenza. CONCLUSIONS: This disease burden estimate confirmed that, although there was a higher mortality observed among young people, the 2009 pandemic was overall a mild influenza epidemic. The disease burden of this pandemic was comparable to the burden of seasonal influenza in the Netherlands.

Antibiotic therapy for acute Q fever in The Netherlands in 2007 and 2008 and its relation to hospitalization.

Data about the effectiveness of different antibiotic regimens for the treatment of acute Q fever from clinical studies is scarce. We analysed the antibiotic treatment regimens of acute Q fever patients in 2007 and 2008 in The Netherlands and assessed whether hospitalization after a minimum of 2 days antibiotic therapy was related to the initial antibiotic therapy. Clinical data on antibiotic treatment and risk factors of acute Q fever patients were obtained from general practitioner medical records and self-reported by patients. For the 438 study patients, doxycycline was the most commonly prescribed initial antibiotic in both study years. After adjustments for confounding factors, doxycycline (200 mg/day), moxifloxacin, as well as other possibly effective antibiotics [including other new fluoroquinolones and doxycycline (100 mg/day)] showed significant lower risks for hospitalization compared to ß-lactam antibiotics and azithromycin (reference group), with the lowest risk for doxycycline (200 mg/day) (odds ratio 0·04, 95% confidence interval 0·01-0·22). These data support current guidelines that recommend doxycycline as the first choice antibiotic for treating acute Q fever.

Increasing trend in gonococcal resistance to ciprofloxacin in The Netherlands, 2006-8.

INTRODUCTION: Rapid development of Neisseria gonorrhoeae resistance to several antibiotics in recent years threatens treatment and prevention. Targeted surveillance of new resistance patterns and insight into networks and determinants are essential to control this trend. METHODS: Since the Gonococcal Resistance to Antimicrobials Surveillance (GRAS) project was implemented within the Dutch national sexually transmitted infection (STI) surveillance network in July 2006, participating STI centres have collected a culture from each gonorrhoea patient. Isolates were tested for susceptibility to penicillin, tetracycline, ciprofloxacin and cefotaxime using Etest. Logistic regression was used to determine risk factors for ciprofloxacin resistance. RESULTS: Between July 2006 and July 2008, prevalence of resistance to penicillin was 10%, to tetracycline 22% and to ciprofloxacin 42%. Resistance to cefotaxime was not found, although minimum inhibitory concentrations higher than 0.125 mg/l drifted upward (p<0.05). Ciprofloxacin resistance rose from 35% in 2006 to 46% in 2008 (p<0.05), despite 2003 guidelines naming cefotaxime as first-choice therapy. In men, ciprofloxacin resistance was higher in men having sex with men (MSM) than in heterosexual men (adjusted OR 2.0, 95% CI : 1.5 to 2.6). In women, it was higher in commercial sex workers (adjusted OR 25.0, 95% CI 7.7 to 78.2) and women aged over 35 years (adjusted OR 8.2, 95% CI 3.0 to 22.7) than in other women. CONCLUSION: Ciprofloxacin resistance in The Netherlands is increasing, and is particularly found in MSM, older women, and female sex workers. No resistance to current first-choice therapy was found, but alertness to potential clinical failures is essential. By merging epidemiological and microbiological data in GRAS, specific high-risk transmission groups can be identified and policy adjusted when needed.

Time trends in primary-care morbidity, hospitalization and mortality due to pneumonia.

Most studies reporting pneumonia morbidity are restricted to hospitalized patients, although only a minority of pneumonia patients are admitted to hospital. To get a better understanding of the burden of disease in the general population, we conducted a population-based retrospective study to examine trends in pneumonia incidence in general practice, hospitalization, and mortality due to pneumonia in The Netherlands between 1997 and 2007. Between 2001/2002 and 2006/2007 there was an adjusted yearly increase of 12% in the clinical diagnosis of pneumonia in patients consulting general practitioners. Hospitalizations increased 5% per year between 1999/2000 and 2006/2007, while mortality annually decreased by 2% between 1997/1998 and 2006/2007. Our study suggests that the morbidity of pneumonia in the Dutch population increased considerably over this period, especially in primary-care settings, and that focusing only on hospitalization might underestimate the increasing public health burden of pneumonia.

Polymorphism in CC-chemokine ligand 2 associated with tuberculosis in Zambia.

Polymorphism in various genes that may influence susceptibility to tuberculosis (TB) was examined in 46 TB patients and 119 healthy tuberculin-positive controls in Zambia. The odds of having TB was 2.8-fold higher in carriers of the -2518 AG single-nucleotide polymorphism in the promoter region of the CC-chemokine ligand 2 than in those carrying the homozygous genotype AA (95%CI 1.3-5.5).

[The use of antiviral agents during an (impending) influenza pandemic]. / Het gebruik van antivirale middelen tijdens een (dreigende) influenzapandemie.

The preventive and therapeutic principles during an (impending) influenza pandemic differ fundamentally from those prevailing during the annual episodes ofinfluenza. Pending the availability of an effective pandemic vaccine, neuraminidase inhibitors are the only effective agents for the prevention and treatment of infections caused by a pandemic influenza virus. The development of an influenza pandemic has 6 phases: phases 3-5 reflect an increasing threat; phase 6 represents a manifest pandemic. During phases 3-5, a maximum effort is made to prevent or delay a pandemic. Neuraminidase inhibitors should be given not only to patients but also to their close contacts (post-exposure prophylaxis). During phase 6, post-exposure prophylaxis is no longer indicated and neuraminidase inhibitors are prescribed for all patients with symptoms ofpandemic influenza. Prophylaxis without preceding close contact with an influenza patient (primary prophylaxis) is recommended only in exceptional cases. Physicians should not prescribe antiviral drugs on demand to concerned citizens for stockpiling.

[Adverse events following influenza vaccination: reaction to specific reports and the necessity of a central registration system]. / Bijwerkingen na influenzavaccinatie: reactie op enkele incidenten en het belang van centrale registratie.

The influenza vaccine is considered safe, but information on vaccine-related adverse events is limited and a nationwide overview of adverse events is lacking. In 2006, after deaths occurred in Israel and the Netherlands following influenza vaccination, the Dutch Ministry of Health, Welfare and Sport (VWS) asked the National Institute for Public Health and the Environment (RIVM) twice for a recommendation regarding the continuation of the national vaccination campaign. After 4 deaths were reported in Israel in October 2006 following administration of Vaxigrip, the Dutch vaccination campaign was suspended for one week. One month later, 4 additional deaths were reported after influenza vaccination in the Netherlands. The newly appointed outbreak management team concluded that a causal relationship between vaccination and the deaths was highly unlikely, based on data regarding the individual cases, background mortality rates and prior reports of adverse events. Further suspension of the vaccination campaign was deemed unnecessary this time. A centralised nationwide registry of adverse events has since been established to provide further insight into the incidence of adverse events following influenza vaccination. Physicians are advised to report potential adverse events following influenza vaccination to the Netherlands Pharmacovigilance Centre Lareb (www.lareb.nl).

Newly identified risk factors for MRSA carriage in The Netherlands.

OBJECTIVES: To elucidate new risk factors for MRSA carriers without known risk factors (MRSA of unknown origin; MUO). These MUO carriers are neither pre-emptively screened nor isolated as normally dictated by the Dutch Search & Destroy policy, thus resulting in policy failure. METHODS: We performed a prospective case control study to determine risk factors for MUO acquisition/carriage (Dutch Trial Register: NTR2041). Cases were MUO carriers reported by participating medical microbiological laboratories to the RIVM from September 1st 2011 until September 1st 2013. Controls were randomly selected from the community during this period. RESULTS: Significant risk factors for MUO in logistic multivariate analysis were antibiotic use in the last twelve months, aOR 8.1 (5.6-11.7), screened as contact in a contact tracing but not detected as a MRSA carrier at that time, aOR 4.3 (2.1-8.8), having at least one foreign parent, aOR 2.4 (1.4-3.9) and receiving ambulatory care, aOR 2.3 (1.4-3.7). Our found risk factors explained 83% of the MUO carriage. CONCLUSIONS: Identifying new risk factors for MRSA carriers remains crucial for countries that apply a targeted screening approach as a Search and Destroy policy or as vertical infection prevention measure.