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Introduction: Influenza vaccination, besides protecting traditional risk groups, can protect employees and reduce illness-related absence, which is especially relevant in sectors with staff shortages. This study describes current knowledge of influenza vaccination in teachers and estimates its potential impact., Methods: We conducted a scoping review of the considerations for and impact of influenza vaccination of schoolteachers (grey and scientific literature up to 2020 March, complemented with interviews). We then estimated the potential impact of teacher vaccination in the Netherlands, with different scenarios of vaccine uptake for 3 influenza seasons (2016-2019). Using published data on multiple input parameters, we calculated potentially averted absenteeism notifications, averted absenteeism duration and averted doctor visits for influenza., Results: Only one scientific paper reported on impact; it showed lower absenteeism in vaccinated teachers, whereas more knowledge of vaccination impact was deemed crucial by 50% of interviewed experts. The impact for the Netherlands of a hypothetical 50% vaccine uptake was subsequently estimated: 74-293 potentially averted physician visits and 11,178-28,896 potentially averted days of influenza absenteeism (on ≈200,000 total teacher population). An estimated 12-32 vaccinations were required to prevent one teacher sick-leave notification, or 3.5-9.1 vaccinations to prevent one day of teacher absenteeism (2016-2019)., Conclusion: Scientific publications on influenza vaccination in teachers are few, while public interest has increased to reduce teacher shortages. However, school boards and public health experts indicate requiring knowledge of impact when considering this vaccination. Estimations of 3.5-9.1 vaccinated teachers preventing one day of influenza-related sick leave suggest a possible substantial vaccination impact on absenteeism. Financial incentives, more accessible on-site vaccinations at workplaces, or both, are expected to increase uptake, but more research is needed on teachers' views and vaccine uptake potential and its cost-effectiveness. Piloting free on-site influenza vaccination in several schools could provide further information on teacher participation., Competing Interests: The authors have declared that no competing interests exist.

Background: Scabies outbreaks are common in nursing homes in the Netherlands. In October 2018, a local public health service (PHS) in The Hague was notified of a new scabies outbreak in a nursing home in that region. The PHS initiated an outbreak investigation. Cases were defined as: possible (reported symptoms), probable (scabies-like lesions) and confirmed (PCR or microscopy in skin flakes). Head-to-toe examinations were performed of all residents and those staff members who reported symptoms suggestive of scabies. Skin scrapings of lesions were tested either with microscopy or by PCR. Experimentally for case finding, skin flakes from bed linens of residents who reported symptoms of itchiness but did not have primary lesions were sent for PCR testing., Principal Findings: All residents (41) and 37/44 staff were included in this outbreak investigation. We identified 30 possible, four probable and six confirmed cases. The overall attack rate for probable/confirmed cases was 10/78 (13%). Of the six confirmed cases, two were confirmed by PCR, three by microscopy, and one showed positive findings with both techniques. Two out of the three bed-linen specimens were PCR-positive., Conclusions: In this outbreak of scabies in a nursing home, PCR was used on skin flakes from bed linens, which led to the detection of two additional cases. This illustrates the potential of PCR during the investigation of scabies outbreaks., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: BW works at Microvida which has Scabies PCR commercially available. The rest of the authors have no conflict of interest.

Background: From 2007 through 2010, a large epidemic of acute Q fever occurred in the Netherlands. Patients with cardiac valvulopathy are at high risk to develop chronic Q fever after an acute infection. This patient group was not routinely screened, so it is unknown whether all their chronic infections were diagnosed. This study aims to investigate how many chronic Q fever patients can be identified by routinely screening patients with valvulopathy and to establish whether the policy of not screening should be changed., Methods: In a cross-sectional study (2016-2017) in a hospital at the epicentre of the Q fever epidemic, a blood sample was taken from patients 18 years and older who presented with cardiac valvulopathy. The sample was tested for IgG antibodies against phase I and II of Coxiella burnetii using an immunofluorescence assay. An IgG phase II titre of ≥1:64 was considered serological evidence of a previous Q fever infection. An IgG phase I titre of ≥1:512 was considered suspicious for a chronic infection, and these patients were referred for medical examination., Results: Of the 904 included patients, 133 (15%) had evidence of a previous C. burnetii infection, of whom 6 (5%) had a chronic infection on medical examination., Conclusions: In a group of high-risk patients with a heart valve defect, we diagnosed new chronic Q fever infections seven years after the epidemic, emphasizing the need for screening of this group to prevent complications in those not yet diagnosed in epidemic areas., Competing Interests: The authors have declared that no competing interests exist.

Background: Burden of disease (BoD) estimations are increasingly used to prioritize public health interventions. Previous Cryptosporidium BoD models accounted only for acute episodes, while there is increasing evidence of long-term manifestations. Our objective was to update Cryptosporidium BoD and cost-of-illness (COI) models and to estimate BoD and COI for the Netherlands in years 2013-2017., Methods: We performed a scoping literature review and drew an outcome tree including long-term manifestations for which sufficient evidence was found, such as recurrent diarrhea and joint pain. We chose the Disability-Adjusted Life Year (DALY) metric to synthesize years of life lost due mortality (YLLs) and years lived with disability due to non-fatal outcomes (YLDs). For the costs, we adopted a societal perspective accounting for direct healthcare costs, patient costs and productivity losses. Uncertainty was managed using Latin Hypercube sampling (30,000 iterations)., Results: In the Netherlands in 2017, we estimated 50,000 Cryptosporidium cases (95% uncertainty interval (UI): 15,000-102,000), 7,000 GP visits, 300 hospitalizations and 3 deaths, resulting in 137 DALYs (95%UI: 54-255) and €19.2 million COI (95%UI: €7.2 million- €36.2 million). Estimates were highest for 2016 (218 DALYs and €31.1 million in COI), and lowest in 2013 (100 DALYs and €13.8 million in COI). Most of the BoD was attributable to YLD (≈80% of DALYs). The most important cost was productivity losses (≈90% of total COI). Long-term manifestations, including recurring diarrhea and joint pain, accounted for 9% of the total DALYs and 7% of the total COI., Conclusion: Current evidence supports the inclusion of long-term manifestations in Cryptosporidium models, which contribute close to 10% of the total DALYs and costs. This may be an underestimation, as we were conservative in our assumptions. Cryptosporidium should be considered a priority organism with respect to public health surveillance, even in industrialized countries with high hygiene standards., Competing Interests: The authors have declared that no competing interests exist.

Background: Understanding and quantification of the risk of Lyme borreliosis after a tick bite can aid development of prevention strategies against Lyme borreliosis., Methods: We used 3,525 single tick bite reports from three large prospective studies on the transmission risk of tick-borne pathogens to humans, with 50 reports of Lyme borreliosis during the follow-up period, among 1,973 reports with known outcome. A structural equation model was applied to estimate the risk of Lyme borreliosis after a tick bite, and quantify the influence of: developmental stage of the tick, detection of Borrelia burgdorferi s.l. DNA in the tick by PCR, tick engorgement, patient-estimated duration of tick attachment, and patient age., Results: The overall risk of developing Lyme borreliosis after a tick bite was 2.6% (95%CI 1.4-5.1). The risk increased with: - Tick engorgement: 1.4% (95%CI 0.7%-2.3%) for low engorgement to 5.5% (95%CI 2.8%-9.2%) for substantially engorged ticks;- Rising patient-estimated tick attachment duration: 2.0% (95%CI 1.3%-2.8%) after <12 hours, to 5.2% (95%CI 3.0%-8.9%) after ≥4 days;- Detection of Borrelia burgdorferi s.l. DNA in ticks: 6.7% (95%CI 3.6%-13.5%), versus 1.4% (95%CI 0.7%-2.9%) when ticks tested negative.The highest observed risk of Lyme borreliosis was 14.4% (95%CI 6.8%-24.6%) after one tick bite of a substantially engorged tick that tested positive for Borrelia burgdorferi s.l. DNA, which corresponds to one new case of Lyme borreliosis per 7 (95%CI 4-15) of such tick bites., Conclusions: An individual's risk of Lyme borreliosis after a tick bite can be predicted with tick engorgement, patient-estimated duration of tick attachment, and detection of Borrelia burgdorferi s.l. DNA in the tick.

We aimed to examine the long-term correlation between influenza vaccination coverage and the incidence of influenza-like illness (ILI) in the total and elderly populations of European countries for which data was available on at least six consecutive influenza seasons. We graphically visualised vaccination coverage and ILI incidence trends and calculated Spearman rank correlation coefficients. Additionally, we fitted a negative binomial regression model to estimate the change in ILI incidence per percentage point change in vaccination coverage. We found significant negative correlations for the total population of the Netherlands (ρ = -0.60, p-value = 0.003) and for the elderly populations of England (ρ = -0.80, p-value < 0.001) and Germany (ρ = -0.57, p-value = 0.04). However, results were not consistent, and for some countries we observed significant positive correlations. Only for the elderly in England was there a significant decline in incidence rate per percentage point increase in vaccination coverage (incidence rate ratio = 0.93; 95% confidence interval 0.88-0.99). Based on this ecological study it is not possible to provide evidence for a negative correlation between influenza vaccination coverage and ILI incidence. For future, aetiological studies to assess impact of influenza vaccinations on the population, there is a need for high quality data over long periods of time, on proportion of ILI caused by influenza virus infection, on severe outcome measures such as hospitalisation for influenza, and on other factors that potentially affect influenza transmission., Competing Interests: The authors have declared that no competing interests exist.

With the ultimate aim of containing the emergence of resistant bacteria, a Dutch policy was set in place in 2010 promoting a reduction of antimicrobial use (AMU) in food-producing animals. In this context, a study evaluated strategies to curb livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA). Fifty-one veal calf farms were assigned to one of 3 study arms: RAB farms reducing antimicrobials by protocol; RAB-CD farms reducing antimicrobials by protocol and applying a cleaning and disinfection program; and Control farms without interventions. MRSA carriage was tested in week 0 and week 12 of 2 consecutive production cycles in farmers, family members and veal calves. Interventions were validated and a cyclic rise in MRSA-prevalence in animals was shown with a more moderate increase in RAB farms. Prevalence in humans declined parallel over time in the study arms but RAB farms were at the lowest MRSA levels from the beginning of the study. In RAB-CD farms, human and animal prevalence did not differ from Control farms and MRSA air loads were significantly higher than in the other study arms. Mimicking the national trend, an overall AMU decrease (daily dosages per animal per cycle (DDDA/C)) was observed over 4 pre-study and the 2 study cycles; this trend did not have a significant effect on a set of evaluated farm technical parameters. AMU was positively associated with MRSA across study arms (ORs per 10 DDDA/C increase = 1.26 for both humans (p = 0.07) and animals (p = 0.12 in first cycle)). These results suggest that AMU reduction might be a good strategy for curbing MRSA in veal calf farming, however the specific cleaning and disinfecting program in RAB-CD farms was not effective. The drop in MRSA prevalence in people during the study could be attributed to the observed long-term AMU decreasing trend.

This prospective cohort study describes carriage of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in household members from 49 farrowing pig farms in the Netherlands (2010-2011). Of 171 household members, 4% were persistent MRSA nasal carriers, and the MRSA prevalence on any given sampling moment was 10% (range 7-11%). Working in the stables (of which 98% was MRSA-positive, prevalence ratio (PR) = 2.11 per 10 hours), working with sows (PR=1.97), and living with an MRSA-positive pig farmer (PR=4.63) were significant determinants for MRSA carriage. Significant protective factors were carriage of methicillin-susceptible Staphylococcus aureus (MSSA) (PR=0.50), and wearing a facemask when working in the stables (37% decreased prevalence). All MRSA strains during the study period were known livestock-associated types. The bacteriophage φ3 was not found in household members. Transmission from pigs and the environment appeared to be important determinants; human-to-human transmission could not sufficiently be differentiated. Wearing a facemask when working in the stables and carriage of MSSA are potential interventional targets.

Incidence of pneumococcal disease is disproportionally high in infants and elderly. Nasopharyngeal colonisation by Streptococcus pneumoniae is considered a prerequisite for disease but unlike in children, carriage in elderly is rarely detected. Here, we tested for S. pneumoniae in nasopharyngeal and saliva samples collected from community-dwelling elderly with influenza-like-illness (ILI). Trans-nasal nasopharyngeal, trans-oral nasopharyngeal and saliva samples (n = 270 per sample type) were collected during winter/spring 2011/2012 from 135 persons aged 60-89 at onset of ILI and 7-9 weeks later following recovery. After samples were tested for pneumococci by conventional culture, all plate growth was collected. DNA extracted from plate harvests was tested by quantitative-PCRs (qPCR) specific for S. pneumoniae and serotypes included in the 13-valent pneumococcal conjugated vaccine (PCV13). Pneumococci were cultured from 14 of 135 (10%) elderly with none of the sampled niches showing superiority in carriage detection. With 76/270 (28%) saliva, 31/270 (11%) trans-oral and 13/270 (5%) trans-nasal samples positive by qPCR, saliva was superior to nasopharyngeal swabs (p<0.001) in qPCR-based carriage detection. Overall, from all methods used in the study, 65 of 135 (48%) elderly carried pneumococci at least once and 26 (19%) at both study time points. The difference between carriage prevalence at ILI (n = 49 or 36%) versus recovery (n = 42 or 31%) was not significant (p = 0.38). At least 23 of 91 (25%) carriage events in 19 of 65 (29%) carriers were associated with PCV13-serotypes. We detected a large reservoir of pneumococci in saliva of elderly, with PCV13-serotype distribution closely resembling the contemporary carriage of serotypes reported in the Netherlands for PCV-vaccinated infants.

Background: Accurate information about the prevalence of Chlamydia trachomatis is needed to assess national prevention and control measures., Methods: We systematically reviewed population-based cross-sectional studies that estimated chlamydia prevalence in European Union/European Economic Area (EU/EEA) Member States and non-European high income countries from January 1990 to August 2012. We examined results in forest plots, explored heterogeneity using the I² statistic, and conducted random effects meta-analysis if appropriate. Meta-regression was used to examine the relationship between study characteristics and chlamydia prevalence estimates., Results: We included 25 population-based studies from 11 EU/EEA countries and 14 studies from five other high income countries. Four EU/EEA Member States reported on nationally representative surveys of sexually experienced adults aged 18-26 years (response rates 52-71%). In women, chlamydia point prevalence estimates ranged from 3.0-5.3%; the pooled average of these estimates was 3.6% (95% CI 2.4, 4.8, I² 0%). In men, estimates ranged from 2.4-7.3% (pooled average 3.5%; 95% CI 1.9, 5.2, I² 27%). Estimates in EU/EEA Member States were statistically consistent with those in other high income countries (I² 0% for women, 6% for men). There was statistical evidence of an association between survey response rate and estimated chlamydia prevalence; estimates were higher in surveys with lower response rates, (p = 0.003 in women, 0.018 in men)., Conclusions: Population-based surveys that estimate chlamydia prevalence are at risk of participation bias owing to low response rates. Estimates obtained in nationally representative samples of the general population of EU/EEA Member States are similar to estimates from other high income countries.

There are indications that livestock-associated MRSA CC398 has a reduced human-to-human transmissibility, limiting its impact on public health and justifying modified control measures. This study determined the transmissibility of MRSA CC398 from livestock veterinarians to their household members in the community as compared to MRSA non-CC398 strains. A one-year prospective cohort study was performed to determine the presence of MRSA CC398 in four-monthly nasal and oropharyngeal samples of livestock veterinarians (n  =  137) and their household members (n  =  389). In addition, a cross-sectional survey was performed to detect the presence of MRSA non-CC398 in hospital derived control patients (n  =  20) and their household members (n  =  41). Staphylococcus aureus isolates were genotyped by staphylococcal protein A (spa) typing and multiple-locus variable-number tandem repeat analysis (MLVA). Mean MRSA CC398 prevalence over the study period was 44% (range 41.6-46.0%) in veterinarians and 4.0% (range 2.8-4.7%) in their household members. The MRSA CC398 prevalence in household members of veterinarians was significantly lower than the MRSA non-CC398 prevalence in household members of control patients (PRR 6.0; 95% CI 2.4-15.5), indicating the reduced transmissibility of MRSA CC398. The impact of MRSA CC398 appears to be low at the moment. However, careful monitoring of the human-to-human transmissibility of MRSA CC398 remains important.

Methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem in both hospitals and communities all over the world. In 2003, a new MRSA clade emerged with a reservoir in pigs and veal calves: livestock-associated MRSA (LA-MRSA). We wanted to estimate the incidence of bacteraemias due to LA-MRSA using national surveillance data from 2009 in the Netherlands. We found a low incidence of LA-MRSA and MRSA bacteraemia episodes, compared to bacteraemias caused by all S. aureus (0.04, 0.18 and 19.3 episodes of bacteraemia per 100,000 inhabitants per year, respectively). LA-MRSA and MRSA were uncommon compared to numbers from other countries as well. MRSA in general and LA-MRSA in specific does not appear to be a public health problem in the Netherlands now. The low incidence of LA-MRSA bacteraemia episodes may best be explained by differences in the populations affected by LA-MRSA versus other MRSA. However, reduced virulence of the strain involved, and the effectiveness of the search and destroy policy might play a role as well.

Background: We performed a nationwide prospective study on the transmission risk for Borrelia to humans, investigating symptoms and serology at enrolment and three months after tick bites, and after standard treatment for erythema migrans (EM). Aiming to quantify the infection risk at point of care by physicians, we explored risk factors such as tick testing for Borrelia and assessment of the duration of the tick's blood meal., Methods and Findings: Questionnaires, blood samples and ticks from patients who consulted one of 307 general practitioners for tick bites (n = 327) or EM (n = 283) in 2007 and 2008, were collected at enrolment and three months later at follow-up. Borrelia burgdorferi sensu lato DNA was detected in 29.3% of 314 ticks, using PCR/reverse line blot and real-time PCR on the OspA gene. Seroconversion in C6 ELISA, IgM or IgG immunoblots for Borrelia-specific antibodies was observed in 3.2% of tick bite cases. Fourteen tick bite cases had evidence of early Borrelia infection, of which EM developed among seven cases. The risk of developing EM after tick bites was 2.6% (95%CI: 1.1%-5.0%), and the risk of either EM or seroconversion was 5.1% (95%CI: 2.9%-8.2%). Participants with Borrelia-positive ticks had a significantly higher risk of either EM or seroconversion (odds ratio 4.8, 95%CI: 1.1-20.4), and of seroconversion alone (odds ratio 11.1, 95%CI: 1.1-108.9). A third (34%) of the cases enrolled with EM did not recall preceding tick bites. Three EM cases (1%) reported persisting symptoms, three months after standard antibiotic treatment for EM., Conclusions: One out of forty participants developed EM within three months after tick bites. The infection risk can be assessed by tick testing for Borrelia at point of care by physicians. However, further refining is needed considering sensitivity and specificity of tick tests, accuracy of tick attachment time and engorgement.

Background: We describe the impact of methicillin-resistant Staphylococcus aureus (MRSA) in two neighbouring regions in Europe with a comparable population size, North Rhine-Westphalia (NRW) in Germany and the Netherlands., Methodology/principal Findings: We compared the occurrence of MRSA in blood cultures from surveillance systems. In the Netherlands in 2009, 14 of 1,510 (0.9%) Staphylococcus aureus bacteraemia episodes under surveillance were MRSA. Extrapolation using the number of clinical admissions results in a total of 29 MRSA bacteraemia episodes in the Netherlands or 1.8 episodes per 1,000,000 inhabitants. In 2010 in NRW, 1,029 MRSA bacteraemias were reported, resulting in 57.6 episodes of MRSA bacteraemia per 1,000,000 inhabitants: a 32-fold higher incidence than in the Netherlands., Conclusion/significance: Based on an estimated attributable mortality of 15%, the Dutch approach would save approximately 150 lives per year by the prevention of bacteraemia only.

Background: Recently, livestock-associated methicillin-resistant Staphylococcus aureus CC398 has been discovered in animals, livestock farmers and retail meat. This cross-sectional study aimed to determine the spread to persons not in direct contact with livestock in areas with a high density of pig farms., Methodology/principal Findings: With a random mailing in 3 selected municipalities in The Netherlands, adult persons were asked to fill in a questionnaire and to take a nose swab. In total, complete information was obtained on 583 persons. Of the 534 persons without livestock-contact, one was positive for MRSA (0.2%; 95% confidence interval, <0.01-1.2). Of the 49 persons who did indicate to be working at or living on a livestock farm, 13 were positive for MRSA (26.5%; 95% confidence interval, 16.1-40.4). All spa-types belonged to CC398., Conclusions/significance: Livestock-associated MRSA has a high prevalence in people with direct contact with animals. At this moment it has not spread from the farms into the community.