Évaluation des sources d’exposition à Mycobacterium avium subsp. paratuberculosis dans les aliments et l’eau

Mycobacterium avium subsp. paratuberculosis (MAP) is believed to be the causative agent of paratuberculosis (Johne’s disease) in ruminants. MAP infection has also been proposed as the cause of Crohn’s disease (CD) in humans. An increasing number of recent studies suggest some association between MAP and CD, however a cause‐effect relationship has yet to be proved or disproved. Infected cattle appear to be the most important source of human exposure to MAP, and the associated suspected vehicles of transmission are milk, dairy products and beef.   Other possible routes of human exposure to MAP are via contaminated water supplies, vegetables and fruits. A low level survival of MAP has been demonstrated in some surveys of commercially pasteurized milk and retail cheese in several countries outside Canada. Viable MAP has been identified in 1.6‐2.9% of pasteurized retail milk and 3.6% of retail cheese samples in several countries. In addition, viable MAP has been found in the intestine and associated lymph tissues of diseased animals as well as in organs other than the gut. The primary purpose of this article is to review the recent scientific evidence on the potential human exposure to MAP via foods and waterOn croit que Mycobacterium avium subsp. paratuberculosis (MAP) est l’agent causal de la paratuberculose (maladie de Johne) chez les ruminants. L’infection par MAP pourrait aussi être en cause dans la maladie de Crohn (MC) chez les humains. Bien qu’un lien de cause à effet doive toujours être démontré ou réfuté, un nombre croissant d’études récentes donnent à penser qu’il existe un lien entre MAP et la MC. Il semble que les bovins infectés, de même que les vecteurs de transmission connexes soupçonnés tels que le lait, les produits laitiers et le bœuf, constituent la principale source d’exposition à MAP chez les humains. L’approvisionnement en eau ainsi que les légumes et les fruits contaminés par MAP sont d’autres voies d’exposition éventuelles à la bactérie chez les humains.   Lors de certaines études sur le lait pasteurisé et les fromages vendus au détail réalisées dans plusieurs pays autres que le Canada, un faible taux de survie de MAP a été démontré. Dans de nombreux autres pays, la prévalence de cellules viables de MAP a été établie à 1,6 à 2,9 % dans des échantillons de lait pasteurisé et à 3,6 % dans des fromages vendus au détail. En outre, MAP viable    a été découverte dans l’intestin et les tissus lymphoïdes associés d’animaux malades, de même que dans des organes autres que l’intestin. Le principal objectif du présent article consiste à examiner les observations scientifiques récentes sur l’exposition potentielle à MAP par les aliments et l’eau chez les humains

Dysregulation of Cytokine Response in Canadian First Nations Communities: Is There an Association with Persistent Organic Pollutant Levels?

In vitro and animal studies report that some persistent organic pollutants (POPs) trigger the secretion of proinflammatory cytokines. Whether POP exposure is associated with a dysregulation of cytokine response remains to be investigated in humans. We studied the strength of association between plasma POP levels and circulating cytokines as immune activation markers. Plasma levels of fourteen POPs and thirteen cytokines were measured in 39 Caucasians from a comparator sample in Québec City (Canada) and 72 First Nations individuals from two northern communities of Ontario (Canada). Caucasians showed significantly higher levels of organochlorine insecticides (β-HCH, p,p′-DDE and HCB) compared to First Nations. Conversely, First Nations showed higher levels of Mirex, Aroclor 1260, PCB 153, PCB 170, PCB 180 and PCB 187 compared to Caucasians. While there was no difference in cytokine levels of IL-4, IL-6, IL-10 and IL-22 between groups, First Nations had significantly greater average levels of IFNγ, IL-1β, IL-2, IL-5, IL-8, IL-12p70, IL-17A, TNFα and TNFβ levels compared to Caucasians. Among candidate predictor variables (age, body mass index, insulin resistance and POP levels), high levels of PCBs were the only predictor accounting for a small but significant effect of observed variance (∼7%) in cytokine levels. Overall, a weak but significant association is detected between persistent organochlorine pollutant exposure and elevated cytokine levels. This finding augments the already existing information that environmental pollution is related to inflammation, a common feature of several metabolic disorders that are known to be especially prevalent in Canada's remote First Nations communities

Use of a Mixture of Surrogates for Infectious Bioagents in a Standard Approach to Assessing Disinfection of Environmental Surfaces ▿

We used a mixture of surrogates (Acinetobacter baumannii, Mycobacterium terrae, hepatitis A virus, and spores of Geobacillus stearothermophilus) for bioagents in a standardized approach to test environmental surface disinfectants. Each carrier containing 10 μl of mixture received 50 μl of a test chemical or saline at 22 ± 2°C. Disinfectant efficacy criteria were ≥6 log10 reduction for the bacteria and the spores and ≥3 log10 reduction for the virus. Peracetic acid (1,000 ppm) was effective in 5 min against the two bacteria and the spores but not against the virus. Chlorine dioxide (CD; 500 and 1,000 ppm) and domestic bleach (DB; 2,500, 3,500, and 5,000 ppm) were effective in 5 min, except for sporicidal activity, which needed 20 min of contact with either 1,000 ppm of CD or the two higher concentrations of DB

Microbicides - the double-edged sword: environmental toxicity and emerging resistance

The growing use of microbicides, while producing significant health and economic benefits for human society, increases environmental concerns with their associated environmental discharge, and increasing risks associated with development of microbial resistance. Similar mechanisms of transfer of resistance between antibiotics and microbicides have resulted in bacterial co-resistance to both groups of chemicals, and evidence is accumulating to suggest that exposure to sub-lethal microbicide levels might sometimes lead to antibiotic resistance. To- date the amount of microbicides used and discharged in the environment cannot be estimated because of the wide range of applications and the lack ofr reporting. Microbicides have been found in the environment at levels that can generate a substantial selective pressure on microbial microcosms. Until more information is available on the effects of such concentrations on microorganisms, a more prudent use of microbicides isshould be recommended to preserve their efficacy and to minimize any negative effects on humans and the environment

Microbiome Profiling of Drinking Water in Relation to Incidence of Inflammatory Bowel Disease

The etiology of IBD is unknown; current research is focused on determining environmental factors. One consideration is drinking water: water systems harbour a considerable diversity of microbes with bacterial concentrations estimated at 106-108 cells per liter. Perhaps differences in microbial ecology of water sources may impact on differential incidence rates of IBD. Regions of Manitoba were geographically mapped according to incidence rates of IBD and identified as high (HIA) or low (LIA) incidence areas. Bulk water, filter material and pipe wall samples were collected from public buildings in different jurisdictions and their population structure analyzed using 16S rDNA sequencing. At the phylum level Proteobacteria were observed significantly less frequently (P=0.02) in HIA versus LIA. The abundance of Proteobacteria was also found to vary according to water treatment distribution networks. Gammaproteobacteria was the most abundant class of bacteria and was observed more frequently (P=0.006) in LIA. At the genus level, microbes found to associate with HIA include Bradyrhizobium (P=0.02) and Pseudomonas (P=0.02). Particular microbes were found to associate with LIA or HIA, based on sample location and/or type. This work lays out a basis for further studies exploring water as a potential environmental source for IBD triggers.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Biofiltration optimization: Phosphorus supplementation effects on disinfection byproduct formation potential

This study investigates the effects of phosphorus supplementation on the formation potential of total trihalomethanes (TTHMfp) and five species of haloacetic acids (HAA5fp) during exposure to clearwell disinfection contact times. In addition, the study investigates the effects of phosphorus supplementation on the dissolved oxygen, organic carbon and nitrogen removal along with biofilm coverage of the filter media and biomass viability of the attached biofilm. The uptake of total phosphorus in the P enhanced filter did not correspond to the consumption of readily assimilated nitrogen or the consumption of soluble carbon. As such, the dissolved organic carbon reduction in the biologically active filters was shown to not be phosphorus nutrient limited. The clearwell TTHMfp was shown to be reduced in all filters across all measured biological filtration times in the control and P enhanced filters. The HAA5fp increased with phosphorus-supplemented operation at specific filtration cycle times as compared to non-phosphorus-supplemented operation, indicating the potential for production of HAA5 with phosphorus supplementation. Enhanced biofilm coverage of the anthracite and sand media was observed during phosphorus supplementation. In addition, increased viability of the cells embedded in the biofilm was observed in the sand media at depth during phosphorus-supplemented operation