Fecal Shedding of Zoonotic Food-Borne Pathogens by Wild Rodents in a Major Agricultural Region of the Central California Coast

Recent outbreaks of food-borne illness associated with the consumption of produce have increased concern over wildlife reservoirs of food-borne pathogens. Wild rodents are ubiquitous, and those living close to agricultural farms may pose a food safety risk should they shed zoonotic microorganisms in their feces near or on agricultural commodities. Fecal samples from wild rodents trapped on 13 agricultural farms (9 produce, 3 cow-calf operations, and 1 beef cattle feedlot) in Monterey and San Benito Counties, CA, were screened to determine the prevalence and risk factors for shedding of several food-borne pathogens. Deer mice (Peromyscus maniculatus) were the most abundant rodent species trapped (72.5%). Cryptosporidium species (26.0%) and Giardia species (24.2%) were the predominant isolates from rodent feces, followed by Salmonella enterica serovars (2.9%) and Escherichia coli O157:H7 (0.2%). Rodent trap success was significantly associated with detection of Salmonella in rodent feces, while farm type was associated with fecal shedding of Cryptosporidium and Giardia. Seasonal shedding patterns were evident, with rodents trapped during the spring and summer months being significantly less likely to be shedding Cryptosporidium oocysts than those trapped during autumn. Higher rodent species diversity tended to correlate with lower fecal microbial prevalence, and most spatiotemporal pathogen clusters involved deer mice. Rodents in the study area posed a minimal risk as environmental reservoirs of E. coli O157:H7, but they may play a role in environmental dissemination of Salmonella and protozoa. Rodent control efforts that potentially reduce biodiversity may increase pathogen shedding, possibly through promotion of intraspecific microbial transmission.     

Comparative study of movement patterns of Mastomys natalensis in irrigated rice and fallow fields in eastern Tanzania

A 2‐year capture–mark–recapture study was conducted to estimate home ranges and weekly travel distance of Mastomys natalensis (Smith 1834) in an irrigated rice ecosystem and fallow fields. We found that adults have larger home ranges than subadults in fallow fields but not in rice fields, indicating that fallow fields are more suitable for breeding. Travel distances were larger in rice fields, especially in the transplanting stage, during which rice fields are flooded and provide less food, causing movements into neighbouring fallow fields that then temporarily experience higher population density. A decrease in travel distance was observed in rice fields during the maturity stage, which can be explained by higher food availability and a more suitable, nonflooded situation. Movement of M. natalensis in rice‐fallow mosaic landscapes thus seems to be driven by food availability and flooding status of the rice fields, which can be attributed to land use practices.     

Evidence of Yersinia pestis DNA from fleas in an endemic plague area of Zambia

Background

Study protocols involving experimental animals often require the monitoring of different parameters not only in anesthetized, but also in free moving animals. Most animal research involves small rodents, in which continuously monitoring parameters such as temperature and heart rate is very stressful for the awake animals or simply not possible. Aim of the underlying study was to monitor heart rate, temperature and activity and to assess inflammation in the heart, lungs, liver and kidney in the early postoperative phase after experimental cardiopulmonary bypass involving 45 min of deep hypothermic circulatory arrest in rats. Besides continuous monitoring of heart rate, temperature and behavioural activity, the main focus was on avoiding uncontrolled death of an animal in the early postoperative phase in order to harvest relevant organs before autolysis would render them unsuitable for the assessment of inflammation.

Findings

We therefore set up a telemetry-based system (Data Science International, DSI?) that continuously monitored the rat's temperature, heart rate and activity in their cages. The data collection using telemetry was combined with an analysis software (Microsoft excel?), a webmail application (GMX) and a text message-service. Whenever an animal's heart rate dropped below the pre-defined threshold of 150 beats per minute (bpm), a notification in the form of a text message was automatically sent to the experimenter's mobile phone. With a positive predictive value of 93.1% and a negative predictive value of 90.5%, the designed surveillance and alarm system proved a reliable and inexpensive tool to avoid uncontrolled death in order to minimize suffering and harvest relevant organs before autolysis would set in.

Conclusions

This combination of a telemetry-based system and software tools provided us with a reliable notification system of imminent death. The system's high positive predictive value helped to avoid uncontrolled death and facilitated timely organ harvesting. Additionally we were able to markedly reduce the drop out rate of experimental animals, and therefore the total number of animals used in our study. This system can be easily adapted to different study designs and prove a helpful tool to relieve stress and more importantly help to reduce animal numbers.     

Plasmid stability and kinetics of continuous production of glucoamylase by recombinant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> in an airlift bioreactor

Production of glucoamylase by recombinant Saccharomyces cerevisiae C468/pGAC9 (ATCC 20690) in a continuous stirred tank bioreactor was studied at different dilution rates. Plasmid stability was found to be growth (dilution rate) dependent; it increased with the dilution rate. Bioreactor productivity and specific productivity also increased with the dilution rate. A kinetic equation was used to model the plasmid stability kinetics. The growth rate ratio between plasmid-carrying and plasmid-free cells decreased from 1.397 to 1.215, and segregational instability or probability of plasmid loss from each cell division decreased from 0.059 to 0.020 as the dilution rate increased from 0.10 to 0.37 1/h. The specific growth rates increased with dilution rate, while the growth rate difference between plasmid-carrying and plasmid-free cell populations was negligible. This was attributed to the low copy number of the hybrid plasmid pGAC9. Thus, the growth rate had no significant effect on plasmid instability. The proposed kinetics was consistent with experimental results, and the model simulated the experimental data well.     

Repeated-batch production of glucoamylase using recombinant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> immobilized in a fibrous bed bioreactor

The recombinant Saccharomyces cerevisiae strain C468/pGAC9 has an unstable hybrid plasmid pGAC9, which directs production of glucoamylase. A fibrous cotton material with a good adsorption capability for recombinant S. cerevisiae cells was used as the immobilization matrix in an internal loop airlift-driven fibrous bed bioreactor (ILALFBB) system. With batch cultures in the ILALFBB, the fraction of plasmid-carrying cells was 72% after more than 2 days cultivation, which was two times higher than that in the conventional free-cell culture. Correspondingly, a high activity of glucoamylase (GA; 113 U/l) was achieved with a high productivity of 43 U/l/h. The ILALFBB system also maintained a high fraction of viable plasmid-carrying of 74% for glucoamylase production during repeated-batch cultures, achieving a high glucoamylase activity of 140 U/l with a productivity of 19–130 U/l/h in all 14 batches studied during 19.8 days. The stable and long-term glucoamylase production from the ILALFBB was attributed to the effect of cell immobilization on plasmid stability. Plasmid-carrying cells were preferentially retained in the fibrous matrix because of their ability to adhere to the fiber surface and to form cell aggregates higher than those of plasmid-free cells. The repeated batch using immobilized cell of recombinant S. cerevisiae in the ALALFBB system thus provides a feasible method for stable, long-term and high-level production of glucoamylase.     

A simplified microwave-based motion detector for home cage activity monitoring in mice

Background

Locomotor activity of rodents is an important readout to assess well-being and physical health, and is pivotal for behavioral phenotyping. Measuring homecage-activity with standard and cost-effective optical methods in mice has become difficult, as modern housing conditions (e.g. individually ventilated cages, cage enrichment) do not allow constant, unobstructed, visual access. Resolving this issue either makes greater investments necessary, especially if several experiments will be run in parallel, or is at the animals’ expense. The purpose of this study is to provide an easy, yet satisfying solution for the behavioral biologist at novice makers level.

Results

We show the design, construction and validation of a simplified, low-cost, radar-based motion detector for home cage activity monitoring in mice. In addition we demonstrate that mice which have been selectively bred for low levels of anxiety-related behavior (LAB) have deficits in circadian photoentrainment compared to CD1 control animals.

Conclusion

In this study we have demonstrated that our proposed low-cost microwave-based motion detector is well-suited for the study of circadian rhythms in mice.

     

Effects of surface treatment and process parameters on immobilization of recombinant yeast cells by adsorption to fibrous matrices

The effects of surface properties of Saccharomyces cerevisiae strains 468/pGAC9 and 468 on adhesion to polyethyleneimine (PEI) and/glutaraldehyde (GA) pre-treated cotton (CT), polyester (PE), polyester + cotton (PECT), nylon (NL), polyurethane foam (PUF), and cellulose re-enforced polyurethane (CPU) fibers were investigated. Process parameters (circulation velocity, pH, ionic strength, media composition and surfactants) were also examined. 80%, 90%, and 35% of the cells were adsorbed onto unmodified CT, PUF, and PE, respectively. PEI-GA pre-treated CT and alkali treated PE yielded 25% and 60% cell adhesion, respectively. Adsorption rate (K_a) ranged from 0.06 to 0.17 for CT and 0.06-0.16 for PE at varied pH. Adhesion increased by 15% in the presence of ethanol, low pH and ionic strength, and decreased by 23% in the presence of yeast extract and glucose. Shear flow and 1% Triton X-100 detached 62% and 36% nonviable cells from PE and CT, respectively, suggesting that cell immobilization in fibrous-bed bioreactors can be controlled to optimize cell density for long-term stability.     

Evaluation of the Distribution and Impacts of Parasites,Pathogens, and Pesticides on Honey Bee (Apis mellifera) Populations in East Africa

In East Africa, honey bees (Apis mellifera) provide critical pollination services and income for small-holder farmers and rural families. While honey bee populations in North America and Europe are in decline, little is known about the status of honey bee populations in Africa. We initiated a nationwide survey encompassing 24 locations across Kenya in 2010 to evaluate the numbers and sizes of honey bee colonies, assess the presence of parasites (Varroa mites and Nosema microsporidia) and viruses, identify and quantify pesticide contaminants in hives, and assay for levels of hygienic behavior. Varroa mites were present throughout Kenya, except in the remote north. Levels of Varroa were positively correlated with elevation, suggesting that environmental factors may play a role in honey bee host-parasite interactions. Levels of Varroa were negatively correlated with levels of hygienic behavior: however, while Varroa infestation dramatically reduces honey bee colony survival in the US and Europe, in Kenya Varroa presence alone does not appear to impact colony size. Nosema apis was found at three sites along the coast and one interior site. Only a small number of pesticides at low concentrations were found. Of the seven common US/European honey bee viruses, only three were identified but, like Varroa, were absent from northern Kenya. The number of viruses present was positively correlated with Varroa levels, but was not correlated with colony size or hygienic behavior. Our results suggest that Varroa, the three viruses, and Nosema have been relatively recently introduced into Kenya, but these factors do not yet appear to be impacting Kenyan bee populations. Thus chemical control for Varroa and Nosema are not necessary for Kenyan bees at this time. This study provides baseline data for future analyses of the possible mechanisms underlying resistance to and the long-term impacts of these factors on African bee populations.     

Two parallel,pragmatic, UK multicentre,randomised controlled trials comparing surgical options for upper compartment (vault or uterine) pelvic organ prolapse (the VUE Study): study protocol for a randomised controlled trial

BackgroundOne in three women who have a prolapse operation will go on to have another operation, though not necessarily in the same compartment. Surgery can result in greater impairment of quality of life than the original prolapse itself (such as the development of new-onset urinary incontinence, or prolapse at a different site). Anterior and posterior prolapse surgery is most common (90 % of operations), but around 43 % of women also have a uterine (34 %) or vault (9 %) procedure at the same time. There is not enough evidence from randomised controlled trials (RCTs) to guide management of vault or uterine prolapse. The Vault or Uterine prolapse surgery Evaluation (VUE) study aims to assess the surgical management of upper compartment pelvic organ prolapse (POP) in terms of clinical effectiveness, cost-effectiveness and adverse events.Methods/designVUE is two parallel, pragmatic, UK multicentre, RCTs (Uterine Trial and Vault Trial). Eligible for inclusion are women with vault or uterine prolapse: requiring a surgical procedure, suitable for randomisation and willing to be randomised. Randomisation will be computer-allocated separately for each trial, minimised on: requiring concomitant anterior and/or posterior POP surgery or not, concomitant incontinence surgery or not, age (under 60 years or 60 years and older) and surgeon. Participants will be randomly assigned, with equal probability to intervention or control arms in either the Uterine Trial or the Vault Trial. Uterine Trial participants will receive either a vaginal hysterectomy or a uterine preservation procedure. Vault Trial participants will receive either a vaginal sacrospinous fixation or an abdominal sacrocolpopexy. Participants will be followed up by postal questionnaires (6 months post surgery and 12 months post randomisation) and also reviewed in clinic 12 months post surgery. The primary outcome is the participant-reported Pelvic Organ Prolapse Symptom Score (POP-SS) at 12 months post randomisation.DiscussionDemonstrating the efficacy of vault and uterine prolapse surgeries is relevant not only to patients and clinicians but also to health care providers, both in the UK and globally.

Trial registration

Current controlled trials ISRCTN86784244 (assigned 19 October 2012), and the first subject was randomly assigned on 1 May 2013 

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1576-x) contains supplementary material, which is available to authorized users.     

“How I Wish This Thing Was Initiated 100 Years Ago!” Willingness to Take Daily Oral Pre-Exposure Prophylaxis among Men Who Have Sex with Men in Kenya

BackgroundThe MSM population in Kenya contributes to 15% of HIV incidence. This calls for innovative HIV prevention interventions. Pre-exposure prophylaxis (PrEP) has been efficacious in preventing HIV among MSM in trials. There is limited data on the willingness to take daily oral PrEP in sub-Sahara Africa. PrEP has not been approved for routine use in most countries globally. This study aimed to document the willingness to take PrEP and barriers to uptake and adherence to PrEP in Kenya. The findings will inform the design of a PrEP delivery program as part of the routine HIV combination prevention.MethodsEighty MSM were recruited in 2 Counties in December 2013. Quantitative data on sexual behaviour and willingness to take PrEP were collected using semi-structured interviews and analysed using SPSS. Qualitative data on knowledge of PrEP, motivators and barriers to uptake and adherence to PrEP were collected using in-depth interviews and FGDs and analysed using Nvivo. Analysis of data in willingness to take PrEP was conducted on the HIV negative participants (n = 55).Results83% of MSM were willing to take daily oral HIV PrEP. Willingness to take PrEP was higher among the bi-sexual and younger men. Motivators for taking PrEP were the need to stay HIV negative and to protect their partners. History of poor medication adherence, fear of side effects and HIV stigma were identified as potential barriers to adherence. Participants were willing to buy PrEP at a subsidized price.ConclusionsThere is willingness to take PrEP among MSM in Kenya and there is need to invest in targeted education and messaging on PrEP to enhance adherence, proper use and reduce stigma in the general population and among policy makers.