Effects of temperature on the transmission of Yersinia Pestis by the flea, Xenopsylla Cheopis, in the late phase period

<p>Abstract</p> <p>Background</p> <p>Traditionally, efficient flea-borne transmission of <it>Yersinia pestis</it>, the causative agent of plague, was thought to be dependent on a process referred to as blockage in which biofilm-mediated growth of the bacteria physically blocks the flea gut, leading to the regurgitation of contaminated blood into the host. This process was previously shown to be temperature-regulated, with blockage failing at temperatures approaching 30°C; however, the abilities of fleas to transmit infections at different temperatures had not been adequately assessed. We infected colony-reared fleas of <it>Xenopsylla cheopis </it>with a wild type strain of <it>Y. pestis </it>and maintained them at 10, 23, 27, or 30°C. Naïve mice were exposed to groups of infected fleas beginning on day 7 post-infection (p.i.), and every 3-4 days thereafter until day 14 p.i. for fleas held at 10°C, or 28 days p.i. for fleas held at 23-30°C. Transmission was confirmed using <it>Y. pestis</it>-specific antigen or antibody detection assays on mouse tissues.</p> <p>Results</p> <p>Although no statistically significant differences in per flea transmission efficiencies were detected between 23 and 30°C, efficiencies were highest for fleas maintained at 23°C and they began to decline at 27 and 30°C by day 21 p.i. These declines coincided with declining median bacterial loads in fleas at 27 and 30°C. Survival and feeding rates of fleas also varied by temperature to suggest fleas at 27 and 30°C would be less likely to sustain transmission than fleas maintained at 23°C. Fleas held at 10°C transmitted <it>Y. pestis </it>infections, although flea survival was significantly reduced compared to that of uninfected fleas at this temperature. Median bacterial loads were significantly higher at 10°C than at the other temperatures.</p> <p>Conclusions</p> <p>Our results suggest that temperature does not significantly effect the per flea efficiency of <it>Y. pestis </it>transmission by <it>X. cheopis</it>, but that temperature is likely to influence the dynamics of <it>Y. pestis </it>flea-borne transmission, perhaps by affecting persistence of the bacteria in the flea gut or by influencing flea survival. Whether <it>Y. pestis </it>biofilm production is important for transmission at different temperatures remains unresolved, although our results support the hypothesis that blockage is not necessary for efficient transmission.</p

The impact of illness in patients with moderate to severe gastro-esophageal reflux disease

BACKGROUND: Gastro-esophageal reflux disease (GERD) is a common disease. It impairs health related quality of life (HRQL). However, the impact on utility scores and work productivity in patients with moderate to severe GERD is not well known. METHODS: We analyzed data from 217 patients with moderate to severe GERD (mean age 50, SD 13.7) across 17 Canadian centers. Patients completed three utility instruments – the standard gamble (SG), the feeling thermometer (FT), and the Health Utilities Index 3 (HUI 3) – and several HRQL instruments, including Quality of Life in Reflux and Dyspepsia (QOLRAD) and the Medical Outcomes Short Form-36 (SF-36). All patients received a proton pump inhibitor, esomeprazole 40 mg daily, for four to six weeks. RESULTS: The mean scores on a scale from 0 (dead) to 1 (full health) obtained for the FT, SG, and HUI 3 were 0.67 (95% CI, 0.64 to 0.70), 0.76 (95% CI, 0.75 to 0.80), and 0.80 (95% CI, 0.77 to 0.82) respectively. The mean scores on the SF-36 were lower than the previously reported Canadian and US general population mean scores and work productivity was impaired. CONCLUSION: GERD has significant impact on utility scores, HRQL, and work productivity in patients with moderate to severe disease. Furthermore, the FT and HUI 3 provide more valid measurements of HRQL in GERD than the SG. After treatment with esomeprazole, patients showed improved HRQL

The cost-effectiveness of exenatide twice daily (BID) vs insulin lispro three times daily (TID) as add-on therapy to titrated insulin glargine in patients with type 2 diabetes

Objective, To evaluate the cost-effectiveness of exenatide twice daily, BID, vs bolus insulin lispro three times daily, TID, as add-on therapy when glycemic control is sub-optimal with titrated basal insulin glargine and metformin. Methods, The analysis was based on the recent, B Study, which compared exenatide BID and lispro TID as add-on therapies in subjects with type, diabetes insufficiently controlled, despite titrated insulin glargine. The Cardiff Diabetes Model was used to simulate patient costs and health benefits beyond the, B Study. The Swedish healthcare perspective was adopted for this analysis, costs are reported in, EUR to aid interpretation. The main outcome measure was the cost per quality-adjusted life-year, QALY, gained with exenatide BID compared to lispro TID. Results, Exenatide BID was associated with an incremental cost of, and a QALY increase of, ., compared with lispro TID over, years. The cost per QALY gained with exenatide BID compared with lispro TID was, which is within conventional limits of cost-effectiveness. Cost-effectiveness results were generally robust to alternative assumptions and values for key model parameters. Limitations, Extrapolation of trial data over the longer term can be influenced by modeling and parameter uncertainty. Cost-effectiveness results were generally insensitive to alternative values of key model input parameters and across scenarios. Conclusions, The addition of exenatide BID rather than insulin lispro to basal insulin is associated with similar or better clinical outcomes. Illustrated from the Swedish healthcare perspective, analysis with the Cardiff Diabetes Model demonstrated that exenatide BID represents a cost-effective treatment alternative to lispro TID as add-on therapy in type, diabetes patients insufficiently controlled on basal insulin.J. Gordon, P. McEwan, U. Sabale, B. Kartman and B. H. R. Wolffenbutte