L. Waddell

Pre-harvest Interventions to Reduce the Shedding of E. coli O157 in the Faeces of Weaned Domestic Ruminants: A Systematic Review

Our objective was to use formal systematic review methods to evaluate the efficacy of interventions to reduce faecal shedding of Escherichia coli O157 in post‐weaned ruminants by increasing animal resistance. The methodology consisted of an extensive search to identify all potentially relevant research, screening of titles and abstracts for relevance to the research question, quality assessment of relevant research, extraction of data from research of sufficient quality, and qualitative summarization of results. The interventions evaluated included probiotics, vaccination, antimicrobials, sodium chlorate, bacteriophages and other feed additives. There was evidence of efficacy for the probiotic combination Lactobacillus acidophilus NP51 (NPC 747) and Propionibacterium freudenreichii and for sodium chlorate in feed or water. The effectiveness of vaccination varied among studies and among vaccine protocols and there was no consistent evidence to suggest that antibiotic use was associated with a decrease in faecal shedding of E. coli O157, or that current industry uses of antimicrobials were associated with increased faecal shedding. There were an insufficient number of studies available to address the effectiveness of bacteriophages and several other feed additives. In general, few of the primary studies evaluated the interventions under commercial housing conditions with a natural disease challenge, there were inconsistencies in the results among study designs and in some cases among studies within study designs, and a relatively large proportion of publications were excluded based on quality assessment criteria. Few studies reported on associations between the proposed intervention and production parameters, such as average daily gain and feed: gain ratio. While the results suggest that some interventions may be efficacious, there are knowledge gaps in our understanding of the efficacy of pre‐harvest interventions to increase animal resistance to E. coli O157 that require further targeted research.

The methodological soundness of literature reviews addressing three potential zoonotic public health issues.

Literature reviews are important information sources for multiple stakeholders in zoonotic public health with limited time to keep up with the rapid increase in primary research in this field. However, their validity depends on their methodological soundness. The study purpose was to evaluate the methodological soundness of literature reviews in zoonotic public health. Relevant reviews (n = 132) published between January 2000 and August 2006 were identified on three issues: Mycobacterium avium ssp paratuberculosis as a potential cause of Crohn’s disease in humans (30 reviews); antimicrobial use in animals as a risk factor for antimicrobial resistance in human pathogens (36); and the zoonotic potential of transmissible spongiform encephalopathies (66). The zoonotic aspect of the issue was the focus of 59 reviews and a subsection of 73 reviews. Two independent reviewers evaluated reviews using 13 criteria: 10 previously validated in the medical field, and three applicable to aetiology research. No review met more than eight of 13 criteria for methodological soundness; two articles met only one criterion. Two reviews described methods for identifying relevant primary research. In only two and four reviews respectively, authors conducted quantitative syntheses of research evidence or reported summarized measures of effect for the zoonotic risk to humans. Recommendations for future research and economic impact were provided in 64 and 10 reviews respectively. In 14 reviews, conclusions exceeded evidence presented. The various review authors’ position on the evidence for the zoonotic association and the zoonotic risk to public health were inconsistent for all three issues. Reviews addressing potential zoonotic public health issues lack structured and transparent methodology preventing the end user from assessing the review’s validity. These reviews should adhere to structured scientific principles similar to what is used for primary research articles.

Examining heterogeneity in the diagnostic accuracy of culture and PCR for Salmonella spp. in swine: a systematic review/meta-regression approach.

The accuracy of bacterial culture and PCR for Salmonella in swine was examined through systematic review of existing primary research in this field. A replicable search was conducted in 10 electronic databases. All steps of the review were conducted by two reviewers: to identify relevant publications, to assess their methodological soundness and reporting, and to extract raw data or reported test accuracy estimates. Meta‐analyses and meta‐regression were performed: to evaluate pooled estimates of test sensitivity (Se) and specificity (Sp), to identify variables explaining the variation in reported test estimates, and to evaluate the association between these variables and reported test Se and Sp. Twenty‐nine studies were included in the review. Unique test evaluations reported in these 29 studies were categorized according to the type of test comparison: culture versus culture (n = 134 test evaluations) and PCR versus culture (n = 21). We identified significant heterogeneity among evaluations for each test category. For culture, more heterogeneity was caused by differences in individual test protocols (52%) than overall differences between studies (16%). Enrichment temperature, study population, agar and enrichment type were significantly associated with variation in culture Se. Furthermore, interaction between enrichment temperature and enrichment type was detected. For PCR, most of the heterogeneity was caused by overall differences between studies (65–70%); sample type and study size were associated with variation in reported PCR Se and Sp. The overall methodological soundness and/or reporting of primary studies included in this review were poor, with variable use of reference standards, and consistent lack of the use or reporting of blinding, randomization and subject (sample) selection criteria. Consequently, the food safety and veterinary public health research community should formally consider ways for standardizing the conduct and reporting of this type of research.

The Accuracy of Diagnostic Tests for Lyme Disease in Humans, A Systematic Review and Meta-Analysis of North American Research.

There has been an increasing incidence of Lyme disease (LD) in Canada and the United States corresponding to the expanding range of the Ixodes tick vector and Lyme disease agent (Borrelia burgdorferi sensu stricto). There are many diagnostic tests for LD available in North America, all of which have some performance issues, and physicians are concerned about the appropriate use and interpretation of these tests. The objective of this systematic review is to summarize the North American evidence on the accuracy of diagnostic tests and test regimes at various stages of LD. Included in the review are 48 studies on diagnostic tests used in North America published since 1995. Thirteen studies examined a two-tier serological test protocol vs. clinical diagnosis, 24 studies examined single assays vs. clinical diagnosis, 9 studies examined single immunoblot vs. clinical diagnosis, 7 studies compared culture or PCR direct detection methods vs. clinical diagnosis, 22 studies compared two or more tests with each other and 8 studies compared a two-tiered serological test protocol to another test. Recent studies examining the sensitivity and specificity of various test protocols noted that the Immunetics® C6 B. burgdorferi ELISA™ and the two tier approach have superior specificity compared to proposed replacements, and the CDC recommended western blot algorithm has equivalent or superior specificity over other proposed test algorithms. There is a dramatic increase in test sensitivity with progression of B. burgdorferi infection from early to late LD. Direct detection methods, culture and PCR of tissue or blood samples were not as sensitive or timely compared to serological testing. It was also noted that there are a large number of both commercial (n = 42) and in-house developed tests used by private laboratories which have not been evaluated in the primary literature.

A systematic review-meta-analysis of primary research investigating the effect of selected alternative treatments on gastrointestinal nematodes in sheep under field conditions.

Selected alternative treatments for preventing or controlling gastrointestinal nematodes (GIN) in sheep under field conditions were evaluated using a systematic review-meta-analysis methodology. Forty-three publications reporting 51 studies (21 controlled studies (CS) and 30 challenge studies (ChS)) and 85 unique treatment comparisons were included in the review. The alternative treatment categories were nutraceuticals (28 studies), breeding for genetic resistance (12), nutritional manipulation (6), homeopathies (2), administration of copper oxide wire particles (2), and biological control (1). Random effect meta-analyses (MA) and meta-regression were performed with the natural logarithm of the difference in means (lnMD) between the control and treatment groups, for fecal egg counts per gram of wet feces (FEC), worm counts (WC) or fecal egg counts per gram of dry matter (FECDM) as the outcome. Treatment effect estimates (lnMD) were back-transformed to their count ratios (CR), a relative measure of effect for controlled versus treated groups, for presentation of results. Significant heterogeneity was observed for both CS and ChS that evaluated nutraceuticals, genetic resistance and nutrition treatments. MA of ChS that investigated nutraceuticals resulted in a significant overall CR of 1.62 (P<0.01) and 1.64 (P<0.01) for FEC and FECDM, respectively and a marginal significant CR of 1.14 (P=0.06) for WC, all favoring the treated groups. MA of CS and ChS that investigated genetic resistance resulted in a significant overall CR of 5.89 and 15.42, respectively (P<0.01), again favoring treated groups. MA of CS that investigated homeopathies with FEC as an outcome were homogenous (I(2)=0.0%) and resulted in a non-significant pooled CR of 1.61. ChS investigating copper oxide wire particle treatments and WC as an outcome, were homogenous (I(2)=0.0%) and had a marginally significant pooled CR of 1.68 (P=0.06). Publication bias was observed for ChS with WC outcomes, indicating that small size studies reporting non-significant CR, were less likely to be published than similar studies that found a significant CR. In a meta-regression, randomization (6.2%) and study size (29.2%) were the main factors contributing to the total variation when the outcome was FEC, and none of the variables contributed to between study heterogeneity. When the outcome was WC, type of treatment was the only significant covariate, explaining 6% of the heterogeneity and 38.5% of the total variation. The methodological soundness and reporting of primary research in the selected studies were low. Our results indicate that from the studied alternative treatments, nutraceuticals and use of genetically resistant sheep might be more promising for control of GINs in sheep.

Barriers and Facilitators to Safe Food Handling among Consumers: A Systematic Review and Thematic Synthesis of Qualitative Research Studies.

Foodborne illness has a substantial health and economic burden on society, and most cases are believed to be due to unsafe food handling practices at home. Several qualitative research studies have been conducted to investigate consumers’ perspectives, opinions, and experiences with safe food handling at home, and these studies provide insights into the underlying barriers and facilitators affecting their safe food handling behaviours. We conducted a systematic review of previously published qualitative studies in this area to synthesize the main across-study themes and to develop recommendations for future consumer interventions and research. The review was conducted using the following steps: comprehensive search strategy; relevance screening of abstracts; relevance confirmation of articles; study quality assessment; thematic synthesis of the results; and quality-of-evidence assessment. A total of 39 relevant articles reporting on 37 unique qualitative studies were identified. Twenty-one barriers and 10 facilitators to safe food handling were identified, grouped across six descriptive themes: confidence and perceived risk; knowledge-behaviour gap; habits and heuristics; practical and lifestyle constraints; food preferences; and societal and social influences. Our overall confidence that each barrier and facilitator represents the phenomenon of interest was rated as high (n = 11), moderate (11), and low (9). Overarching analytical themes included: 1) safe food handling behaviours occur as part of a complex interaction of everyday consumer practices and habituation; 2) most consumers are not concerned about food safety and are generally not motivated to change their behaviours based on new knowledge about food safety risks; and 3) consumers are amenable to changing their safe food handling habits through relevant social pressures. Key implications and recommendations for research, policy and practice are discussed.

Implications of applying methodological shortcuts to expedite systematic reviews: three case studies using systematic reviews from agri‐food public health

Background The rapid review is an approach to synthesizing research evidence when a shorter timeframe is required. The implications of what is lost in terms of rigour, increased bias and accuracy when conducting a rapid review have not yet been elucidated. Methods We assessed the potential implications of methodological shortcuts on the outcomes of three completed systematic reviews addressing agri‐food public health topics. For each review, shortcuts were applied individually to assess the impact on the number of relevant studies included and whether omitted studies affected the direction, magnitude or precision of summary estimates from meta‐analyses. Results In most instances, the shortcuts resulted in at least one relevant study being omitted from the review. The omission of studies affected 39 of 143 possible meta‐analyses, of which 14 were no longer possible because of insufficient studies (<2). When meta‐analysis was possible, the omission of studies generally resulted in less precise pooled estimates (i.e. wider confidence intervals) that did not differ in direction from the original estimate. Conclusions The three case studies demonstrated the risk of missing relevant literature and its impact on summary estimates when methodological shortcuts are applied in rapid reviews.

Powassan virus, a scoping review of the global evidence

Powassan virus (POWV), a flavivirus discovered in 1958, causes sporadic but severe cases of encephalitis in humans. Since 2007, the number of human Powassan cases diagnosed each year in the USA has steadily increased. This is in agreement with predictions that Powassan cases may increase in North America as a result of increased exposure to infected ticks. However, the increase may also reflect improved diagnostics and reporting among other factors.

Explaining the food safety behaviours of food handlers using theories of behaviour change: a systematic review

ABSTRACT Theories of behaviour change can explain the factors affecting food handlers’ use of food safety practices. A systematic review was conducted on this topic to identify which theories have been applied in this area and to determine which theories are the most consistent predictors of food handlers’ behaviours. Standard systematic review procedures were followed: comprehensive search strategy; relevance screening of abstracts; article characterization; data extraction; risk-of-bias assessment; and descriptive analysis. Among 19 relevant studies, the most commonly investigated theories were the Theory of Planned Behaviour (n = 9 studies) and Health Belief Model (n = 5). All investigated theories were useful to explain food handlers’ behavioural intentions and behaviours related to food safety across different settings, and could serve as useful frameworks for future research and practice. However, there was wide variability in the predictive ability of the theories and their specific constructs, indicating theories should be adapted to the local context of application.

Risk perceptions, attitudes, and knowledge of chikungunya among the public and health professionals: a systematic review

BackgroundRecently, attention to chikungunya has increased due to its spread into previously non-endemic areas. Since there is no available treatment or vaccine, most intervention strategies focus on mosquito bite prevention and mosquito control, which require community involvement to be successful. Thus, our objective was to systematically review the global primary literature on the risk perceptions, attitudes, and knowledge of chikungunya among the public and health professionals to inform future research and improve our understanding on which intervention strategies are likely to be successful.MethodsPotentially relevant articles were identified through a standardized systematic review (SR) process consisting of the following steps: comprehensive search strategy in seven databases (Scopus, PubMed, CINAHL, CAB, LILACS, Agricola, and Cochrane) and a grey literature search of public health organizations, relevance screening, risk of bias assessment, and data extraction. Two independent reviewers performed each step. Reporting of this SR follows PRISMA reporting guidelines.ResultsThirty-seven relevant articles were identified. The majority of the articles were published since 2011 (83.8%) and reported on studies conducted in Asia (48.7%) and the Indian Ocean Islands (24.3%). The results were separated into four categories: general knowledge and perceptions on chikungunya; perceptions on the risk and severity of chikungunya; knowledge of chikungunya-harboring vectors and transmission; and knowledge, perceptions, and attitudes on mitigation practices. Overall, the systematic review found that risk perceptions, attitudes, and knowledge of chikungunya among the public and health professionals vary across populations and countries and knowledge is higher in areas that have experienced an outbreak.ConclusionThe results suggest that most of the affected populations in this study do not understand mosquito borne diseases or chikungunya and are therefore less likely to protect themselves from mosquito bites. While more research is required to improve the generalizability of this dataset, it appears that a lack of knowledge is an important barrier for motivating community level interventions and personal protection against mosquitoes.