Disease burden of psittacosis in the Netherlands.

Psittacosis (infection with Chlamydia psittaci) can have diverse presentations in humans, ranging from asymptomatic infection to severe systemic disease. Awareness of psittacosis and its presentations are low among clinicians and the general public. Therefore, underdiagnosis and thereby underestimation of the incidence and public health importance of psittacosis is very likely. We used the methodology developed for the Burden of communicable diseases in Europe toolkit of the European Centre for Disease Prevention and Control, to construct a model to estimate disease burden in disability-adjusted life years (DALYs) attributable to psittacosis. Using this model, we estimated the disease burden caused by psittacosis in the Netherlands to have been 222 DALY per year (95% CI 172-280) over the period 2012-2014. This is comparable with the amount of DALYs estimated to be due to rubella or shigellosis in the same period in the Netherlands. Our results highlight the public health importance of psittacosis and identify evidence gaps pertaining to the clinical presentations and prognosis of this disease.

The incidence of symptomatic infection with influenza virus in the Netherlands 2011/2012 through 2016/2017, estimated using Bayesian evidence synthesis.

Due to differences in the circulation of influenza viruses, distribution and antigenic drift of A subtypes and B lineages, and susceptibility to infection in the population, the incidence of symptomatic influenza infection can vary widely between seasons and age-groups. Our goal was to estimate the symptomatic infection incidence in the Netherlands for the six seasons 2011/2012 through 2016/2017, using Bayesian evidence synthesis methodology to combine season-specific sentinel surveillance data on influenza-like illness (ILI), virus detections in sampled ILI cases and data on healthcare-seeking behaviour. Estimated age-aggregated incidence was 6.5 per 1000 persons (95% uncertainty interval (UI): 4.7-9.0) for season 2011/2012, 36.7 (95% UI: 31.2-42.8) for 2012/2013, 9.1 (95% UI: 6.3-12.9) for 2013/2014, 41.1 (95% UI: 35.0-47.7) for 2014/2015, 39.4 (95% UI: 33.4-46.1) for 2015/2016 and 27.8 (95% UI: 22.7-33.7) for season 2016/2017. Incidence varied substantially between age-groups (highest for the age-group <5 years: 23 to 47/1000, but relatively low for 65+ years: 2 to 34/1000 over the six seasons). Integration of all relevant data sources within an evidence synthesis framework has allowed the estimation - with appropriately quantified uncertainty - of the incidence of symptomatic influenza virus infection. These estimates provide valuable insight into the variation in influenza epidemics across seasons, by virus subtype and lineage, and between age-groups.

Chlamydia psittaci (psittacosis) as a cause of community-acquired pneumonia: a systematic review and meta-analysis.

Psittacosis is a zoonotic infectious disease caused by the transmission of the bacterium Chlamydia psittaci from birds to humans. Infections in humans mainly present as community-acquired pneumonia (CAP). However, most cases of CAP are treated without diagnostic testing, and the importance of C. psittaci infection as a cause of CAP is therefore unclear. In this meta-analysis of published CAP-aetiological studies, we estimate the proportion of CAP caused by C. psittaci infection. The databases MEDLINE and Embase were systematically searched for relevant studies published from 1986 onwards. Only studies that consisted of 100 patients or more were included. In total, 57 studies were selected for the meta-analysis. C. psittaci was the causative pathogen in 1·03% (95% CI 0·79-1·30) of all CAP cases from the included studies combined, with a range between studies from 0 to 6·7%. For burden of disease estimates, it is a reasonable assumption that 1% of incident cases of CAP are caused by psittacosis.

COVID-19 vaccination-induced antibody responses and waning by age and comorbidity status in a large population-based prospective cohort study.

BACKGROUND: Information on the magnitude and duration of antibody levels after COVID-19 vaccination in different groups may be useful for prioritizing of additional vaccinations. METHODS: Serum samples were collected every six months in a prospective cohort study among adults in the Netherlands. Geometric mean concentrations (GMCs) of antibodies against the receptor binding domain of the SARS-CoV-2 spike protein were calculated after the primary series, first, and second booster vaccinations. Effects of age (18-59 vs 60-85 years) and medical risk conditions on GMC 2-6 weeks and 21-25 weeks after each vaccination, and on waning during 3-25 weeks after each vaccination, were estimated by linear regression. RESULTS: We included 20,640, 15,229 and 8,392 samples collected after primary, first and second booster vaccination, respectively. GMCs at 2-6 and 21-25 weeks after primary series were lower in participants with older age or medical risk conditions. After the first booster, older age was associated with lower GMC at 2-6 weeks and at 21-25 weeks. Waning after the first and second boosters (only 60-85) was not associated with age or medical risk conditions. CONCLUSIONS: Since antibody differences by age and medical risk groups have become small with increasing number of doses, other factors such as COVID-19 disease severity rather than antibody levels are useful for prioritization of additional vaccinations.

Burden of surgical site infections in the Netherlands: cost analyses and disability-adjusted life years.

BACKGROUND: Surgical site infections (SSIs) are associated with morbidity, mortality and costs. AIM: To identify the burden of (deep) SSIs in costs and disability-adjusted life years (DALYs) following colectomy, mastectomy and total hip arthroplasty (THA) in the Netherlands. METHODS: A retrospective cost-analysis was performed using 2011 data from the national SSI surveillance network PREZIES. Sixty-two patients with an SSI (exposed) were matched to 122 patients without an SSI (unexposed, same type of surgery). Patient records were studied until 1 year after SSI diagnosis. Unexposed patients were followed for the same duration. Costs were calculated from the hospital perspective (2016 price level), and cost differences were tested using linear regression analyses. Disease burden was estimated using the Burden of Communicable Disease in Europe Toolkit of the European Centre for Disease Prevention and Control. The SSI model was specified by type of surgery, with country- and surgery-specific parameters where possible. FINDINGS: Attributable costs per SSI were €21,569 (THA), €14,084 (colectomy) and €1881 (mastectomy), mainly caused by prolonged length of hospital stay. National hospital costs were estimated at €10 million, €29 million and €0.6 million, respectively. National disease burden was greatest for SSIs following colectomy (3200 DALYs/year, 150 DALYs/100 SSIs), while individual disease burden was highest following THA (1200 DALYs/year, 250 DALYs/100 SSIs). For mastectomy, these DALYs were <1. The total cost of DALYs for the three types of surgery exceeded €88 million. CONCLUSION: Depending on the type of surgery, SSIs cause a significant burden, both economically and in loss of years in full health. This underlines the importance of appropriate infection prevention and control measures.