Distance to pig farms as risk factor for community-onset livestock-associated MRSA CC398 infection in persons without known contact to pig farms-A nationwide study

MRSA CC398 is an emerging MRSA strain found in livestock, mainly in pigs. Direct occupational livestock contact is the principal risk factor for human MRSA CC398 infection. Nonetheless, in recent years, an increasing number of MRSA CC398 cases has been observed in persons without known pig contact. Such cases, referred to as MRSA CC398 of unknown origin (MUO CC398), have, like livestock-onset (LO) MRSA CC398 cases, been found concentrated in rural, livestock-producing areas. The presence of MUO CC398 cases indicates alternative and unknown MRSA CC398 transmission pathways into the community. We performed a nationwide study in Denmark of the geographic distributions of MRSA cases in general and persons with MUO CC398 or LO MRSA CC398 infections (1 January 2006-11 February 2015), with the Danish population as background population. Place of living of study persons was mapped using the ArcGIS software, and information on pig farms was retrieved from the Central Husbandry Register. The incidence of MUO CC398 infections was clearly higher in rural than in urban areas, and such cases lived on average closer to pig farms than the general population. However, within three pig-farming-dense municipalities, patients with MUO CC398 infections did not live closer to pig farms than population controls. This shows that direct environmental spread from neighbouring pig farms of MRSA CC398 is unlikely. Instead, community spread through other means of transmission than direct spread from farms may more likely explain the clustering of MUO CC398 in livestock-dense areas.

Population-level impact, herd immunity, and elimination after human papillomavirus vaccination: a systematic review and meta-analysis of predictions from transmission-dynamic models

BACKGROUND

Modelling studies have been widely used to inform human papillomavirus (HPV) vaccination policy decisions; however, many models exist and it is not known whether they produce consistent predictions of population-level effectiveness and herd effects. We did a systematic review and meta-analysis of model predictions of the long-term population-level effectiveness of vaccination against HPV 16, 18, 6, and 11 infection in women and men, to examine the variability in predicted herd effects, incremental benefit of vaccinating boys, and potential for HPV-vaccine-type elimination.

METHODS

We searched MEDLINE and Embase for transmission-dynamic modelling studies published between Jan 1, 2009, and April 28, 2015, that predicted the population-level impact of vaccination on HPV 6, 11, 16, and 18 infections in high-income countries. We contacted authors to determine whether they were willing to produce new predictions for standardised scenarios. Strategies investigated were girls-only vaccination and girls and boys vaccination at age 12 years. Base-case vaccine characteristics were 100% efficacy and lifetime protection. We did sensitivity analyses by varying vaccination coverage, vaccine efficacy, and duration of protection. For all scenarios we pooled model predictions of relative reductions in HPV prevalence (RRprev) over time after vaccination and summarised results using the median and 10th and 90th percentiles (80% uncertainty intervals [UI]).

FINDINGS

16 of 19 eligible models from ten high-income countries provided predictions. Under base-case assumptions, 40% vaccination coverage and girls-only vaccination, the RRprev of HPV 16 among women and men was 0·53 (80% UI 0·46-0·68) and 0·36 (0·28-0·61), respectively, after 70 years. With 80% girls-only vaccination coverage, the RRprev of HPV 16 among women and men was 0·93 (0·90-1·00) and 0·83 (0·75-1·00), respectively. Vaccinating boys in addition to girls increased the RRprev of HPV 16 among women and men by 0·18 (0·13-0·32) and 0·35 (0·27-0·39) for 40% coverage, and 0·07 (0·00-0·10) and 0·16 (0·01-0·25) for 80% coverage, respectively. The RRprev were greater for HPV 6, 11, and 18 than for HPV 16 for all scenarios investigated. Finally at 80% coverage, most models predicted that girls and boys vaccination would eliminate HPV 6, 11, 16, and 18, with a median RRprev of 1·00 for women and men for all four HPV types. Variability in pooled findings was low, but increased with lower vaccination coverage and shorter vaccine protection (from lifetime to 20 years).

INTERPRETATION

Although HPV models differ in structure, data used for calibration, and settings, our population-level predictions were generally concordant and suggest that strong herd effects are expected from vaccinating girls only, even with coverage as low as 20%. Elimination of HPV 16, 18, 6, and 11 is possible if 80% coverage in girls and boys is reached and if high vaccine efficacy is maintained over time.

FUNDING

Canadian Institutes of Health Research.

Challenges and opportunities in mapping land use intensity globally

Future increases in land-based production will need to focus more on sustainably intensifying existing production systems. Unfortunately, our understanding of the global patterns of land use intensity is weak, partly because land use intensity is a complex, multidimensional term, and partly because we lack appropriate datasets to assess land use intensity across broad geographic extents. Here, we review the state of the art regarding approaches for mapping land use intensity and provide a comprehensive overview of available global-scale datasets on land use intensity. We also outline major challenges and opportunities for mapping land use intensity for cropland, grazing, and forestry systems, and identify key issues for future research.

Dengue outbreaks in high-income area, Kaohsiung City, Taiwan, 2003-2009

Cases distribute in a clustered pattern, and elderly persons have the highest risk for illness and death.

Kaohsiung City, a modern metropolis of 1.5 million persons, has been the focus of dengue virus activity in Taiwan for several decades. The aim of this study was to provide a temporal and spatial description of dengue virus epidemiology in Kaohsiung City by using data for all laboratory-confirmed dengue cases during 2003–2009. We investigated age- and sex-dependent incidence rates and the spatiotemporal patterns of all cases confirmed through passive or active surveillance. Elderly persons were at particularly high risk for dengue virus–related sickness and death. Of all confirmed cases, ≈75% were detected through passive surveillance activities; case-patients detected through active surveillance included immediate family members, neighbors, and colleagues of confirmed case-patients. Changing patterns of case clustering could be due to the effect of unmeasured environmental and demographic factors.