Combining epidemiological and ecological methods to quantify social effects on Escherichia coli transmission.

Enteric microparasites like Escherichia coli use multiple transmission pathways to propagate within and between host populations. Characterizing the relative transmission risk attributable to host social relationships and direct physical contact between individuals is paramount for understanding how microparasites like E. coli spread within affected communities and estimating colonization rates. To measure these effects, we carried out commensal E. coli transmission experiments in two cattle (Bos taurus) herds, wherein all individuals were equipped with real-time location tracking devices. Following transmission experiments in this model system, we derived temporally dynamic social and contact networks from location data. Estimated social affiliations and dyadic contact frequencies during transmission experiments informed pairwise accelerated failure time models that we used to quantify effects of these sociobehavioural variables on weekly E. coli colonization risk in these populations. We found that sociobehavioural variables alone were ultimately poor predictors of E. coli colonization in feedlot cattle, but can have significant effects on colonization hazard rates (p ≤ 0.05). We show, however, that observed effects were not consistent between similar populations. This work demonstrates that transmission experiments can be combined with real-time location data collection and processing procedures to create an effective framework for quantifying sociobehavioural effects on microparasite transmission.

Demographic and psychological moderators of the relationship between neighborhood cigarette advertising and current smoking in New York City.

BACKGROUND: Tobacco advertising in retailers influences smoking, but little research has examined how this relationship differs among population subgroups. This study merged data on neighborhood cigarette advertising with geocoded survey data to assess the association between advertising prevalence and current smoking among New York City (NYC) residents, and whether demographic and psychological characteristics moderate this relationship. METHODS: Audit data from a stratified, random sample of 796 NYC tobacco retailers generated neighborhood prevalence estimates of cigarette advertising, which were linked with unweighted 2017 NYC Community Health Survey data (n = 7837 adult respondents with residential geocodes). Multilevel regression estimated adjusted odds ratios (aOR) of current smoking by level of neighborhood cigarette advertising (quartiles). Interactions assessed differences in this relationship by demographic characteristics and current depression (analyses conducted in 2019). RESULTS: There was no main effect of advertising on smoking status or significant interactions with demographic variables, but current depression was an effect modifier (p = 0.045). Cigarette advertising was associated with current smoking among those with current depression (p = 0.023), not those without (p = 0.920). Specifically, respondents with depression who resided in neighborhoods in the highest quartile for cigarette advertising prevalence had higher odds of current smoking, compared to those living in the lowest advertising quartile [aOR: 1.72 (1.04, 2.86)]. CONCLUSION: Retail cigarette advertising may serve as an environmental cue to smoke among adults with depression. Efforts to restrict or counteract this practice, such as the development of community-level public health interventions and counter-marketing programs, may particularly benefit those with depression and, perhaps, other mental health disorders.

Implementing structural equation models to observational data from feedlot production systems.

The objective of this study was to illustrate the implementation of a mixed-model-based structural equation modeling (SEM) approach to observational data in the context of feedlot production systems. Different from traditional multiple-trait models, SEMs allow assessment of potential causal interrelationships between outcomes and can effectively discriminate between direct and indirect effects. For illustration, we focused on feedlot performance and its relationship to health outcomes related to Bovine Respiratory Disease (BRD), which accounts for approximately 75% of morbidity and 50-80% of deaths in feedlots. Our data consisted of 1430 lots representing 178,983 cattle from 9 feedlot operations located across the US Great Plains. We explored functional links between arrival weight (AW; i = 1), BRD-related treatment costs (Trt$; as a proxy for health; i = 2) and average daily weight gain (ADG; as an indicator of productive performance i = 3), accounting for the fixed effect of sex and correlation patterns due to the clustering of lots within feedlots. We proposed competing plausible causal models based on expert knowledge. The best fitting model selected for inference supported direct effects of AW on ADG as well as indirect effects of AW on ADG mediated by Trt$. Direct effects from outcome i' to outcome i are quantified by the structural coefficient λii', such that every unit increase in kg/head of AW had a direct effect of increasing ADG by approximately (estimate ±â€¯standard error) λˆ31=0.002±0.0001 kg/head/day and also a direct effect of reducing Trt$ by an estimated λˆ21=$0.08±0.006 USD per head. In addition, every $1 USD spent on Trt$ directly decreased ADG by an estimated λˆ32=0.004±0.0006 kg/head/day. From these estimates, we show how to compute the indirect, Trt$-mediated, effect of AW on ADG, as well as the overall effect of AW on ADG, including both direct and indirect effects. We further compared estimates of SEM-based effects with those obtained from standard linear regression mixed models and demonstrated the additional advantage of explicitly distinguishing direct and indirect components of an overall regression effect using SEMs. Understanding the direct and indirect mechanisms of interplay between health and performance outcomes may provide valuable insight into production systems.

A new approach to sex-based classifications in the context of procreative rights: S.H. & Others V. Austria in context.

A critical discussion of the recent First Section and Grand Chamber judgments of the European Court of Human Rights in the case of S.H. and Others v. Austria, which upheld an Austrian ban on in-vitro fertilisation (IVF) using donor gametes (ova and sperm). The author argues that the regulatory regime adopted by Austria is overbroad insofar as the regime it adopts fails to accurately reflect the legitimate interests of the state. This is not a conventional "controversial morals" case where, in the absence of a clear moral and/or policy consensus among the Council of Europe member states, states are properly accorded a wide margin of appreciation. The regime adopted by Austria embodies a clear sex bias (with their respective gametes standing as near perfect proxies for the sex of the applicants) with exceptions being made to address male infertility while leaving women without medical remedy. As such, the margin of appreciation should be significantly restricted and the classifications embodied by the regime subject to the highest possible scrutiny.

A simulation model to quantify the value of implementing whole-herd Bovine viral diarrhea virus testing strategies in beef cow-calf herds.

Although numerous diagnostic tests are available to identify cattle persistently infected (PI) with Bovine viral diarrhea virus (BVDV) in cow-calf herds, data are sparse when evaluating the economic viability of individual tests or diagnostic strategies. Multiple factors influence BVDV testing in determining if testing should be performed and which strategy to use. A stochastic model was constructed to estimate the value of implementing various whole-herd BVDV cow-calf testing protocols. Three common BVDV tests (immunohistochemistry, antigen-capture enzyme-linked immunosorbent assay, and polymerase chain reaction) performed on skin tissue were evaluated as single- or two-test strategies. The estimated testing value was calculated for each strategy at 3 herd sizes that reflect typical farm sizes in the United States (50, 100, and 500 cows) and 3 probabilities of BVDV-positive herd status (0.077, 0.19, 0.47) based upon the literature. The economic value of testing was the difference in estimated gross revenue between simulated cow-calf herds that either did or did not apply the specific testing strategy. Beneficial economic outcomes were more frequently observed when the probability of a herd being BVDV positive was 0.47. Although the relative value ranking of many testing strategies varied by each scenario, the two-test strategy composed of immunohistochemistry had the highest estimated value in all but one herd size-herd prevalence permutation. These data indicate that the estimated value of applying BVDV whole-herd testing strategies is influenced by the selected strategy, herd size, and the probability of herd BVDV-positive status; therefore, these factors should be considered when designing optimum testing strategies for cow-calf herds.

Prevalence of Escherichia coli O157:H7 in gut contents of beef cattle at slaughter.

Fecal shedding of Escherichia coli O157:H7 in cattle, except those that shed transiently, is due to the organism's ability to persist in the gut. Site of prevalence in the gut is important for understanding the mechanisms and factors affecting gut persistence and fecal shedding and is a potential target for intervention. The prevalence of E. coli O157:H7 in the rumen, cecum, colon, and rectum was determined with contents collected from slaughtered cattle (n = 815) at an abattoir. Isolation and identification of E. coli O157:H7 were by selective enrichment, immunomagnetic separation, plating on selective medium, agglutination for O157 antigen, and presence of virulence genes. Prevalence in the rumen, cecum, colon, and rectum was 4.9%, 9.9%, 7.6%, and 11.1%, respectively. The overall prevalence of E. coli O157:H7 in the cattle sampled, based on being positive in any one gut location, was 20.3%. E. coli O157:H7 in rectal contents was positively associated (p < 0.01) with presence in the rumen or colon but not in the cecum. Pulsed-field gel electrophoresis (PFGE) was performed to compare the clonal similarity of isolates (n = 144) obtained from the rectum with that of rumen, cecum, or colon within cattle (n = 77). The majority (79-90%) of isolates obtained within the same animal shared a common PFGE type. There were no significant differences in PFGE type between positive samples from the rectum and samples from other locations within the same animal. Acid tolerance for cattle with positive rumen (pregastric) isolates and with at least one other positive hindgut (postgastric) isolate within the same animal was determined. There was no significant difference between gut locations in log reduction following acid challenge. The hindgut was the major site of prevalence of E. coli O157:H7 in cattle, a majority of the isolates within the same animal were clonally similar, and acid tolerance of hindgut isolates were not different from that of ruminal isolates.