The nematode (Ascaris suum) intestine is a location of synergistic anthelmintic effects of Cry5B and levamisole.

A novel group of biocidal compounds are the Crystal 3D (Cry) and Cytolytic (Cyt) proteins produced by Bacillus thuringiensis (Bt). Some Bt Cry proteins have a selective nematocidal activity, with Cry5B being the most studied. Cry5B kills nematode parasites by binding selectively to membrane glycosphingolipids, then forming pores in the cell membranes of the intestine leading to damage. Cry5B selectively targets multiple species of nematodes from different clades and has no effect against mammalian hosts. Levamisole is a cholinergic anthelmintic that acts by selectively opening L-subtype nicotinic acetylcholine receptor ion-channels (L-AChRs) that have been found on muscles of nematodes. A synergistic nematocidal interaction between levamisole and Cry5B at the whole-worm level has been described previously, but the location, mechanism and time-course of this synergism is not known. In this study we follow the timeline of the effects of levamisole and Cry5B on the Ca2+ levels in enterocyte cells in the intestine of Ascaris suum using fluorescence imaging. The peak Ca2+ responses to levamisole were observed after approximately 10 minutes while the peak responses to activated Cry5B were observed after approximately 80 minutes. When levamisole and Cry5B were applied simultaneously, we observed that the responses to Cry5B were bigger and occurred sooner than when it was applied by itself. It is proposed that the synergism is due to the cytoplasmic Ca2+ overload that is induced by the combination of levamisole opening Ca2+ permeable L-subtype nAChRs and the Ca2+ permeable Cry5B toxin pores produced in the enterocyte plasma membranes. The effect of levamisole potentiates and speeds the actions of Cry5B that gives rise to bigger Ca2+ overloads that accelerates cell-death of the enterocytes.

Transcatheter Aortic Valve Replacement With the Navitor System: Real-World United Kingdom Experience.

The Navitor transcatheter heart valve (THV) is the latest iteration of the Portico self-expanding valve system. Early prospective studies have shown promising outcomes, however, there is a lack of complementary 'real-world' data. This study aimed to assess early safety and efficacy outcomes of the Navitor THV using registry data from 6 high-volume United Kingdom transcatheter aortic valve replacement (TAVR) centers. Demographic, procedural, and in-hospital outcome data were retrieved from 6 United Kingdom centers. The primary safety end point was 30-day mortality. Primary efficacy end points were procedural success, mean aortic gradient, and ≥moderate paravalvular leak. Secondary end points included rates of new permanent pacemaker implantation, stroke, and vascular injury. A total of 574 patients (mean age 83.4 years; 54.5% female) underwent Navitor TAVR between January 2020 and May 2023. The 30-day mortality in this patient cohort was 1.6%. Procedural success was 98.1%, mean echo-derived gradient post-TAVR was 7.7 ± 4.8 mm Hg (95% confidence interval [CI] 7.2 to 8.3, p <0.001) and 5.1% of patients had ≥moderate paravalvular leak (sample proportion estimate [p̂] = 0.051, 95% CI [0.035, 0.073], p <0.001). New permanent pacemaker implantation to discharge was required in 11% (p̂ = 0.119, 95% CI 0.088 to 0.158, p <0.001), stroke occurred in 1.2% of patients (p̂ = 0.017, 95% CI 0.006 to 0.036, p <0.001) and significant vascular injury in 1.6% (p̂ = 0.014, 95% CI 0.005 to 0.032, p <0.001). In conclusion, early procedural outcomes with Navitor TAVR compare favorably to new-generation THVs. Procedural success was high with a low incidence of complications.

Getting around the roundworms: Identifying knowledge gaps and research priorities for the ascarids.

The ascarids are a large group of parasitic nematodes that infect a wide range of animal species. In humans, they cause neglected diseases of poverty; many animal parasites also cause zoonotic infections in people. Control measures include hygiene and anthelmintic treatments, but they are not always appropriate or effective and this creates a continuing need to search for better ways to reduce the human, welfare and economic costs of these infections. To this end, Le Studium Institute of Advanced Studies organized a two-day conference to identify major gaps in our understanding of ascarid parasites with a view to setting research priorities that would allow for improved control. The participants identified several key areas for future focus, comprising of advances in genomic analysis and the use of model organisms, especially Caenorhabditis elegans, a more thorough appreciation of the complexity of host-parasite (and parasite-parasite) communications, a search for novel anthelmintic drugs and the development of effective vaccines. The participants agreed to try and maintain informal links in the future that could form the basis for collaborative projects, and to co-operate to organize future meetings and workshops to promote ascarid research.

Balloon aortic valvuloplasty with or without percutaneous coronary intervention in the TAVR era.

Introduction The role of balloon aortic valvuloplasty (BAV) amid the era of transcatheter aortic valve replacement (TAVR) remains a topic of debate. We sought to study the safety and feasibility of combined balloon aortic valvuloplasty and percutaneous coronary intervention (BAV-PCI). Methods Between November 2009 and July 2020, all patients undergoing BAV were identified and divided into three groups: combined BAV-PCI (group A), BAV with significant unrevascularised CAD (group B) and BAV without significant CAD (group C). Procedural outcomes, 30-day and one-year mortality were compared. Results A total of 264 patients were studied (n = 84, 93 and 87 patients in group A, B and C, respectively). The STS score was 10.2 ±8, 13.3 ±19 and 8.1 ±7, p = 0.026, in group A, B and C, respectively. VARC-3 adjudicated complications were similar among groups (11%, 13% and 5%, respectively, p = 0.168, respectively). Thirty-day and one-year mortality were 9.8% (n =26) and 32% (n = 86) of the entire cohort. The differences among groups did not reach statistical significance. Using univariate Cox regression analysis, group B were at higher risk of dying compared to group A patients (HR 1.58, 95% CI 1.11 - 2.25, p = 0.010). With multivariate Cox regression analysis, the predictors of mortality were STS score, cardiogenic shock, and mode of presentation and lack of subsequent definitive valve intervention. Conclusion In high-risk patients with aortic valve stenosis, combined BAV-PCI is safe and feasible with comparable outcomes to BAV with and without significant CAD.

The nematode (Ascaris suum) intestine is a location of synergistic anthelmintic effects of Cry5B and levamisole.

A novel group of biocidal compounds are the Crystal 3D (Cry) and Cytolytic (Cyt) proteins produced by Bacillus thuringiensis (Bt). Some Bt Cry proteins have a selective nematocidal activity, with Cry5B being the most studied. Cry5B kills nematode parasites by binding selectively to membrane glycosphingolipids, then forming pores in the cell membranes of the intestine leading to damage. Cry5B selectively targets multiple species of nematodes from different clades and has no effect against mammalian hosts. Levamisole is a cholinomimetic anthelmintic that acts by selectively opening L-subtype nicotinic acetylcholine receptor ion-channels (L-AChRs) that have been found on muscles of nematodes. A synergistic nematocidal interaction between levamisole and Cry5B has been described previously, but the location, mechanism and time-course of this synergism is not known. In this study we follow the timeline of the effects of levamisole and Cry5B on the Ca2+ levels in enterocyte cells from the intestine of Ascaris suum using fluorescence imaging. The peak Ca2+ responses to levamisole were observed after approximately 10 minutes while the peak responses to activated Cry5B were observed after approximately 80 minutes. When levamisole and Cry5B were applied simultaneously, we observed that the responses to Cry5B were bigger and occurred sooner than when it was applied by itself. It is proposed that there is an irreversible cytoplasmic Ca2+ overload that leads to necrotic cell-death in the enterocyte that is induced by levamisole opening Ca2+ permeable L-subtype nAChRs and the development of Ca2+ permeable Cry5B toxin pores in enterocyte plasma membranes. The effects of levamisole potentiate and speed the actions of Cry5B.

Diethylcarbamazine elicits Ca2+ signals through TRP-2 channels that are potentiated by emodepside in Brugia malayi muscles.

Filarial nematode infections are a major health concern in several countries. Lymphatic filariasis is caused by Wuchereria bancrofti and Brugia spp. affecting over 120 million people. Heavy infections can lead to elephantiasis, which has serious effects on individuals' lives. Although current anthelmintics are effective at killing microfilariae in the bloodstream, they have little to no effect against adult parasites found in the lymphatic system. The anthelmintic diethylcarbamazine is one of the central pillars of lymphatic filariasis control. Recent studies have reported that diethylcarbamazine can open transient receptor potential (TRP) channels in the muscles of adult female Brugia malayi, leading to contraction and paralysis. Diethylcarbamazine has synergistic effects in combination with emodepside on Brugia, inhibiting motility: emodepside is an anthelmintic that has effects on filarial nematodes and is under trial for the treatment of river blindness. Here, we have studied the effects of diethylcarbamazine on single Brugia muscle cells by measuring the change in Ca2+ fluorescence in the muscle using Ca2+-imaging techniques. Diethylcarbamazine interacts with the transient receptor potential channel, C classification (TRPC) ortholog receptor TRP-2 to promote Ca2+ entry into the Brugia muscle cells, which can activate Slopoke (SLO-1) Ca2+-activated K+ channels, the putative target of emodepside. A combination of diethylcarbamazine and emodepside leads to a bigger Ca2+ signal than when either compound is applied alone. Our study shows that diethylcarbamazine targets TRP channels to promote Ca2+ entry that is increased by emodepside activation of SLO-1 K+ channels.

Diethylcarbamazine elicits Ca 2+ signals through TRP-2 channels that are potentiated by emodepside in Brugia malayi muscles.

Filarial nematode infections are a major health concern in several countries. Lymphatic filariasis is caused by Wucheria bancrofti and Brugia spp. affecting over 120 million people. Heavy infections can lead to elephantiasis having serious effects on individuals’ lives. Although current anthelmintics are effective at killing the microfilariae in the bloodstream, they have little to no effect against adult parasites found in the lymphatic system. The anthelmintic diethylcarbamazine is one of the central pillars of lymphatic filariasis control. Recent studies have reported that diethylcarbamazine can open Transient Receptor Potential (TRP) channels on the muscles of adult female Brugia malayi leading to contraction and paralysis. Diethylcarbamazine has synergistic effects in combination with emodepside on Brugia inhibiting motility: emodepside is an anthelmintic that has effects on filarial nematodes and is under trials for treatment of river blindness. Here we have studied the effects of diethylcarbamazine on single Brugia muscle cells by measuring the change in Ca 2+ fluorescence in the muscle using Ca 2+ -imaging techniques. Diethylcarbamazine interacts with the TRPC orthologue receptor TRP-2 to promote Ca 2+ entry into the Brugia muscle cells which can activate SLO-1 Ca 2+ activated K + channels, the putative target of emodepside. A combination of diethylcarbamazine and emodepside leads to a bigger Ca 2+ signal than when either compound is applied alone. Our study shows that diethylcarbamazine targets TRP channels to promote Ca 2+ entry that is increased by emodepside activation of SLO-1 channels.

Diethylcarbamazine, TRP channels and Ca2+ signaling in cells of the Ascaris intestine.

The nematode parasite intestine absorbs nutrients, is involved in innate immunity, can metabolize xenobiotics and as we show here, is also a site of action of the anthelmintic, diethylcarbamazine. Diethylcarbamazine (DEC) is used to treat lymphatic filariasis and activates TRP-2, GON-2 & CED-11 TRP channels in Brugia malayi muscle cells producing spastic paralysis. DEC also has stimulatory effects on ascarid nematode parasites. Using PCR techniques, we detected, in Ascaris suum intestine, message for: Asu-trp-2, Asu-gon-2, Asu-ced-11, Asu-ocr-1, Asu-osm-9 and Asu-trpa-1. Comparison of amino-acid sequences of the TRP channels of B. malayi, and A. suum revealed noteworthy similarity, suggesting that the intestine of Ascaris will also be sensitive to DEC. We used Fluo-3AM as a Ca2+ indicator and observed characteristic unsteady time-dependent increases in the Ca2+ signal in the intestine in response to DEC. Application of La3+ and the TRP channel inhibitors, 2-APB or SKF 96365, inhibited DEC mediated increases in intracellular Ca2+. These observations are important because they emphasize that the nematode intestine, in addition to muscle, is a site of action of DEC as well as other anthelmintics. DEC may also enhance the Ca2+ toxicity effects of other anthelmintics acting on the intestine or, increase the effects of other anthelmintics that are metabolized and excreted by the nematode intestine.

Reduced Ca2+ transient amplitudes may signify increased or decreased depolarization depending on the neuromodulatory signaling pathway.

Neuromodulators regulate neuronal excitability and bias neural circuit outputs. Optical recording of neuronal Ca2+ transients is a powerful approach to study the impact of neuromodulators on neural circuit dynamics. We are investigating the polymodal nociceptor ASH in Caenorhabditis elegans to better understand the relationship between neuronal excitability and optically recorded Ca2+ transients. ASHs depolarize in response to the aversive olfactory stimulus 1-octanol (1-oct) with a concomitant rise in somal Ca2+, stimulating an aversive locomotory response. Serotonin (5-HT) potentiates 1-oct avoidance through Gαq signaling, which inhibits L-type voltage-gated Ca2+ channels in ASH. Although Ca2+ signals in the ASH soma decrease, depolarization amplitudes increase because Ca2+ mediates inhibitory feedback control of membrane potential in this context. Here, we investigate octopamine (OA) signaling in ASH to assess whether this negative correlation between somal Ca2+ and depolarization amplitudes is a general phenomenon, or characteristic of certain neuromodulatory pathways. Like 5-HT, OA reduces somal Ca2+ transient amplitudes in ASH neurons. However, OA antagonizes 5-HT modulation of 1-oct avoidance behavior, suggesting that OA may signal through a different pathway. We further show that the pathway for OA diminution of ASH somal Ca2+ consists of the OCTR-1 receptor, the Go heterotrimeric G-protein, and the G-protein activated inwardly rectifying channels IRK-2 and IRK-3, and this pathway reduces depolarization amplitudes in parallel with somal Ca2+ transient amplitudes. Therefore, even within a single neuron, somal Ca2+ signal reduction may indicate either increased or decreased depolarization amplitude, depending on which neuromodulatory signaling pathways are activated, underscoring the need for careful interpretation of Ca2+ imaging data in neuromodulatory studies.

Anthelmintic resistance and homeostatic plasticity (Brugia malayi).

Homeostatic plasticity refers to the capacity of excitable cells to regulate their activity to make compensatory adjustments to long-lasting stimulation. It is found across the spectrum of vertebrate and invertebrate species and is driven by changes in cytosolic calcium; it has not been explored in parasitic nematodes when treated with therapeutic drugs. Here we have studied the adaptation of Brugia malayi to exposure to the anthelmintic, levamisole that activates muscle AChR ion-channels. We found three phases of the Brugia malayi motility responses as they adapted to levamisole: an initial spastic paralysis; a flaccid paralysis that follows; and finally, a recovery of motility with loss of sensitivity to levamisole at 4 h. Motility, calcium-imaging, patch-clamp and molecular experiments showed the muscle AChRs are dynamic with mechanisms that adjust their subtype composition and sensitivity to levamisole. This homeostatic plasticity allows the parasite to adapt resisting the anthelmintic.

Adapting techniques for calcium imaging in muscles of adult Brugia malayi.

Brugia malayi is a human filarial nematode parasite that causes lymphatic filariasis or 'elephantiasis' a disfiguring neglected tropical disease. This parasite is a more tractable nematode parasite for the experimental study of anthelmintic drugs and has been studied with patch-clamp and RNAi techniques. Unlike in C. elegans however, calcium signaling in B. malayi or other nematode parasites has not been achieved, limiting the studies of the mode of action of anthelmintic drugs. We describe here the development of calcium imaging methods that allow us to characterize changes in cellular calcium in the muscles of B. malayi. This is a powerful technique that can help in elucidating the mode of action of selected anthelmintics. We developed two approaches that allow the recording of calcium signals in the muscles of adult B. malayi: (a) soaking the muscles with Fluo-3AM, promoting large-scale imaging of multiple cells simultaneously and, (b) direct insertion of Fluo-3 using microinjection, providing the possibility of performing dual calcium and electrophysiological recordings. Here, we describe the techniques used to optimize dye entry into the muscle cells and demonstrate that detectable increases in Fluo-3 fluorescence to elevated calcium concentrations can be achieved in B. malayi using both techniques.

Increased shear in the North Atlantic upper-level jet stream over the past four decades.

Earth's equator-to-pole temperature gradient drives westerly mid-latitude jet streams through thermal wind balance1. In the upper atmosphere, anthropogenic climate change is strengthening this meridional temperature gradient by cooling the polar lower stratosphere2,3 and warming the tropical upper troposphere4-6, acting to strengthen the upper-level jet stream7. In contrast, in the lower atmosphere, Arctic amplification of global warming is weakening the meridional temperature gradient8-10, acting to weaken the upper-level jet stream. Therefore, trends in the speed of the upper-level jet stream11-13 represent a closely balanced tug-of-war between two competing effects at different altitudes14. It is possible to isolate one of the competing effects by analysing the vertical shear-the change in wind speed with height-instead of the wind speed, but this approach has not previously been taken. Here we show that, although the zonal wind speed in the North Atlantic polar jet stream at 250 hectopascals has not changed since the start of the observational satellite era in 1979, the vertical shear has increased by 15 per cent (with a range of 11-17 per cent) according to three different reanalysis datasets15-17. We further show that this trend is attributable to the thermal wind response to the enhanced upper-level meridional temperature gradient. Our results indicate that climate change may be having a larger impact on the North Atlantic jet stream than previously thought. The increased vertical shear is consistent with the intensification of shear-driven clear-air turbulence expected from climate change18-20, which will affect aviation in the busy transatlantic flight corridor by creating a more turbulent flying environment for aircraft. We conclude that the effects of climate change and variability on the upper-level jet stream are being partly obscured by the traditional focus on wind speed rather than wind shear.

Rapid Aspirin Desensitization is Safe and Feasible in Patients With Stable and Unstable Coronary Artery Disease: A Single-Center Experience.

AIMS: There are limited data on aspirin (ASA) desensitization for patients with coronary disease. We present our experience with a rapid nurse-led oral desensitization regimen in patients with aspirin sensitivity undergoing coronary angiography. METHODS: This single-center retrospective observational study includes patients with a history of ASA sensitivity undergoing coronary angiography with intent to perform percutaneous coronary intervention (PCI). RESULTS: Between January 2012 and January 2017, 24 patients undergoing coronary angiography for stable coronary disease (7 cases) or acute coronary syndromes (non-ST-segment myocardial infarction [NSTEMI; 8 cases], STEMI [9 cases]) underwent aspirin desensitization having reported previous reactions to aspirin. At initial presentation, previous sensitivity reactions were reported as: mucocutaneous reactions in 17 patients (urticaria in 3 [13%], nonurticarial rash in 6 [25%], angio-oedema in 8 [33%]), respiratory sensitivity in 4 (17%), and systemic anaphylactoid reactions in 3 (13%). Seventeen (71%) patients underwent PCI. Desensitization was acutely successful in 22 (92%) patients and unsuccessful in 2 (8%) patients who both had a single short-lived episode of acute bronchospasm treated successfully with nebulized salbutamol. Fifteen successfully desensitized patients completed 12 months of aspirin; no patient had recurrent hypersensitivity reaction. Aspirin was stopped prior to 12 months in 7 patients (replaced by warfarin [1 case], no antiplatelet or single antiplatelet clinically indicated and clopidogrel chosen [4 cases], patient choice without evidence of recurrent hypersensitivity [1 case], and death due to cardiogenic shock following STEMI [1 case]). CONCLUSION: A rapid aspirin desensitization protocol is safe and effective across a broad spectrum of hypersensitivity reactions and clinical presentations.

Optical Coherence Tomography Evaluation of Coronary Dissection and Intramural Hematoma.

Image series shows an extensive intramural hematoma causing luminal compression corresponding to the angiographic stenosis. Although intramural hematomas are identifiable on intravascular ultrasound, OCT offers superior characterization and exclusion of alternate diagnoses, such as plaque erosion.

Transradial Secondary Access to Guide Valve Implantation and Manage Peripheral Vascular Complications During Transcatheter Aortic Valve Implantation.

BACKGROUND: Vascular complications from transfemoral (TF) secondary access during transcatheter aortic valve implantation (TAVI) are common. We compare our experience of transradial (TR) versus transfemoral secondary access during TAVI and describe techniques for performing iliofemoral arterial intervention from the transradial approach. METHODS: All TAVI procedures with a single secondary access were included. Demographics, procedural details and 30-day outcomes were recorded. VARC-2 criteria were used for procedural complications. Procedures with TF primary access were stratified by the site of secondary arterial access. RESULTS: Single secondary access was used in 199 cases, of which 20 were performed via non-TF access. Of the 179 TF primary access cases, 115 (64%) used TR secondary access and 64 (36%) used TF secondary access. In the TR cohort percutaneous vascular intervention was performed from the transradial approach in 19 cases (17%). Emergent TF secondary access was not required in any case. There were no differences in procedural time, radiation dose, contrast use, bleeding complications, stroke or mortality between the groups. There was one secondary access complication in the TF cohort and none in the TR cohort. CONCLUSIONS: Transradial (TR) secondary access during TAVI is safe and feasible and may reduce the secondary access site vascular complication rate. With appropriate equipment, most peripheral vascular complications can be managed entirely via TR access avoiding unplanned femoral arterial access. TR secondary access should be considered the default approach for non-TF TAVI cases and can be considered for all TF cases as long as dedicated equipment is available.

Outcomes after culprit-only percutaneous coronary intervention for multivessel disease during ST-segment elevation myocardial infarction: a comparison of registry and clinical trial outcomes.

BACKGROUND: The PRAMI and CvLPRIT trials support preventive percutaneous coronary intervention (PCI) for multivessel coronary disease found during ST-segment elevation myocardial infarction (STEMI). We assess our real-world experience of the management of multivessel disease identified during primary PCI (PPCI) in a large UK regional centre. PATIENTS AND METHODS: All STEMI patients who underwent culprit-only PPCI during the study period (August 2011 to August 2013) were retrospectively assessed for eligibility to each trial. The two resulting groups were designated as the 'observational' cohorts. Primary outcomes were then determined and compared with the culprit-only revascularisation cohorts from the respective published randomized controlled trials (RCTs). RESULTS: A total of 1143 consecutive cases were presented during the study period. Of these, 343 would have been suitable for inclusion to PRAMI and were included in the 'observational PRAMI' cohort; 196 patients were included in the 'observational CvLPRIT' cohort.The 'observational PRAMI' cohort experienced fewer primary outcome events (13.1 vs. 22.9%), cardiac deaths (0.6 vs. 4.3%) and nonfatal myocardial infarctions (3.5 vs. 8.7%) than the culprit-only PCI PRAMI cohort (n=231); there were significantly more diabetics (P=0.022) and anterior STEMI initial presentations in the culprit-only PCI PRAMI cohort. Primary outcomes were comparable to those of the preventive PCI PRAMI cohort.The 'observational CvLPRIT' cohort showed no significant difference in primary outcomes over 12 months (16.8 vs. 21.2%), but significantly lower all-cause mortality (2 vs. 6.9%) than the culprit-only PCI CvPLRIT cohort (n=146). The 30-day event rates were similar to the preventive PCI arm; the 12-month events were better than the nonpreventive, but not as good as the preventive RCT cohorts. CONCLUSION: Outcomes from culprit-only primary PCI for multivessel disease in patients selected by the RCT criteria from an all-comers population representing real-life experience are better than those published in the two main RCTs. The RCTs may have selected a high-risk population for study exaggerating the benefits of preventive PCI.

Measurement of microvascular function in patients presenting with thrombolysis for ST elevation myocardial infarction, and PCI for non-ST elevation myocardial infarction.

BACKGROUND: In this prospective study, we compared the invasive measures of microvascular function in two subsets: patients with pharmacoinvasive thrombolysis for STEMI, and patients undergoing percutaneous coronary intervention (PCI) for NSTEMI. METHODS: The study consisted of 17 patients with STEMI referred for cardiac catheterisation post thrombolysis, and 20 patients with NSTEMI. Coronary physiological indexes were measured in each patient before and after PCI. RESULTS: The median pre-PCI index of microcirculatory function (IMR) at baseline was significantly higher in the STEMI group than the NSTEMI group (26 units vs. 15 units, p = 0.02). Following PCI, IMR decreased in both groups (STEMI 20 units vs. NSTEMI 14 units, p = 0.10). There was an inverse correlation between post PCI IMR and left ventricular ejection fraction (LVEF) (r = -0.52, p = 0.001). Furthermore, post PCI IMR was an independent predictor of index admission LVEF in the total population (ß = -0.388, p = 0.02). CONCLUSION: Invasive measures of microvascular function are inferior in a pharmacoinvasive STEMI group compared to a clinically stable NSTEMI group. In the STEMI population, the IMR following coronary intervention appears to predict LVEF.

On-farm storage of livestock vaccines may be a risk to vaccine efficacy: a study of the performance of on-farm refrigerators to maintain the correct storage temperature.

BACKGROUND: Livestock vaccines (LV) are often stored on-farm, in a refrigerator (fridge), prior to use and little is documented about the storage conditions during this period. As the quality of a vaccine can be impaired by storage at an incorrect temperature, the present study aimed to evaluate the on-farm performance of farm fridges to maintain the correct storage temperature. From January to August 2014, temperature data loggers were placed on selected farms fridges used to store LV (n = 20) in South-West England. RESULTS: Temperature recording data was available from 17 of the 20 farms. Fifty-nine percent of farm fridges had at least one temperature recording above 8 °C, 53% had at least one recording below 2 °C and 41% at or below 0 °C. Internal fridge temperatures attained 24 °C and dropped to - 12 °C as an absolute maximum and minimum respectively. Fridges tested spent an average of 16% of the total time recorded above 8 °C. Time of the year significantly influenced the percentage of time above 8 °C. External and internal temperatures were found to be positively correlated (p < 0.001). Statistical significant differences in internal and external temperatures were found between March and August. CONCLUSIONS: The majority of fridges in this study would have failed to keep any stored LV within the recommended storage temperature range. If LV are going to be stored on-farm prior to use, then urgent improvements in this part of the cold-chain are required in order to insure vaccine efficacy is not compromised.

Incomplete host immunity favors the evolution of virulence in an emergent pathogen.

Immune memory evolved to protect hosts from reinfection, but incomplete responses that allow future reinfection may inadvertently select for more-harmful pathogens. We present empirical and modeling evidence that incomplete immunity promotes the evolution of higher virulence in a natural host-pathogen system. We performed sequential infections of house finches with Mycoplasma gallisepticum strains of various levels of virulence. Virulent bacterial strains generated stronger host protection against reinfection than less virulent strains and thus excluded less virulent strains from infecting previously exposed hosts. In a two-strain model, the resulting fitness advantage selected for an almost twofold increase in pathogen virulence. Thus, the same immune systems that protect hosts from infection can concomitantly drive the evolution of more-harmful pathogens in nature.