Range expansion of Dermacentor variabilis and Dermacentor andersoni (Acari: Ixodidae) near their northern distributional limits.

Distributional ranges of the ticks Dermacentor andersoni Stiles and Dermacentor variabilis (Say) in the Canadian Prairies were determined by passive surveillance and active collection. These findings were compared with historical records of both species, particularly in the province of Saskatchewan, where the northern distributional limits of both tick species occur. Before the 1960s, D. variabilis and D. andersoni were allopatric in Saskatchewan; however, since then, the distribution of D. variabilis has expanded westward and northward. Although the range of D. andersoni has remained relatively stable, range expansion of D. variabilis has resulted in a zone of sympatry at least 200 km wide. Twenty-nine species of mammals and three species of birds were identified as hosts for different life stages of these ticks.

Primary graft dysfunction following lung transplantation: From pathogenesis to future frontiers.

Lung transplantation is the treatment of choice for patients with end-stage lung disease. Currently, just under 5000 lung transplants are performed worldwide annually. However, a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction. It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant. This review aims to provide an in-depth analysis of the epidemiology, patho physiology, risk factors, outcomes, and future frontiers involved in mitigating primary graft dysfunction. The current diagnostic criteria are examined alongside changes from the previous definition. We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion. Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality, ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.

The Glasgow Experience of Extended Myocardial Protection: A Novel Method of Implantation to Reduce Primary Graft Dysfunction After Heart Transplant.

OBJECTIVES: Around 2000 heart transplants are performed in Europe annually. The rates of primary graft dysfunction in Europe are among the highest in the world. With increasing demand for organs and the limited supply of donors, novel techniques such as ex vivo normothermic perfusion have garnered incre-asing interest. We present a series of patients who underwent heart transplant at our unit in which we used a novel implantation technique to reduce primary graft dysfunction. MATERIALS AND METHODS: We compared our experience with the novel method detailed in our article (Glasgow experience group) with a contemporary UK cohort (2015-2016) of patients (control group). We performed multivariable logistic regression to compare the Glasgow experience with the control group with primary graft dysfunction as the outcome measure. We adjusted for donor age, recipient diabetes mellitus, urgent listing status, bypass time, and total ischemic time. RESULTS: Among 194 patients in both cohorts, 140 patients (72.1%) were men and 36 (18.6%) had ischemic cardiomyopathy. The odds ratio of primary graft dysfunction in the control group was 2.99 (95% CI, 1.02- 8.75) compared with the Glasgow experience group. CONCLUSIONS: Our novel approach was associated with significant reductions in primary graft dysfunction, with a trend toward improved 1-year survival. Larger studies are needed to show differences after further adjustment for known confounders of primary graft dysfunction. We believe this novel technique is safe, cost-effective, and reproducible.

A national pilot of donation after circulatory death (DCD) heart transplantation within the United Kingdom.

BACKGROUND: The United Kingdom (UK) was one of the first countries to pioneer heart transplantation from donation after circulatory death (DCD) donors. To facilitate equity of access to DCD hearts by all UK heart transplant centers and expand the retrieval zone nationwide, a Joint Innovation Fund (JIF) pilot was provided by NHS Blood and Transplant (NHSBT) and NHS England (NHSE). The activity and outcomes of this national DCD heart pilot program are reported. METHODS: This is a national multi-center, retrospective cohort study examining early outcomes of DCD heart transplants performed across 7 heart transplant centers, adult and pediatric, throughout the UK. Hearts were retrieved using the direct procurement and perfusion (DPP) technique by 3 specialist retrieval teams trained in ex-situ normothermic machine perfusion. Outcomes were compared against DCD heart transplants before the national pilot era and against contemporaneous donation after brain death (DBD) heart transplants, and analyzed using Kaplan-Meier analysis, chi-square test, and Wilcoxon's rank-sum. RESULTS: From September 7, 2020 to February 28, 2022, 215 potential DCD hearts were offered of which 98 (46%) were accepted and attended. There were 77 potential donors (36%) which proceeded to death within 2 hours, with 57 (27%) donor hearts successfully retrieved and perfused ex situ and 50 (23%) DCD hearts going on to be transplanted. During this same period, 179 DBD hearts were transplanted. Overall, there was no difference in the 30-day survival rate between DCD and DBD (94% vs 93%) or 90 day survival (90% vs 90%) respectively. There was a higher rate of ECMO use post-DCD heart transplants compared to DBD (40% vs 16%, p = 0.0006), and DCD hearts in the pre pilot era, (17%, p = 0.002). There was no difference in length of ICU stay (9 DCD vs 8 days DBD, p = 0.13) nor hospital stay (28 DCD vs 27 DBD days, p = 0.46). CONCLUSION: During this pilot study, 3 specialist retrieval teams were able to retrieve DCD hearts nationally for all 7 UK heart transplant centers. DCD donors increased overall heart transplantation in the UK by 28% with equivalent early posttransplant survival compared with DBD donors.

Predicting weekly variation of Culex tarsalis (Diptera: Culicidae) West Nile virus infection in a newly endemic region, the Canadian prairies.

West Nile virus (WNV) spread across most of North America within a short time period after its incursion into the Western Hemisphere. The Canadian prairies had the highest human incidence of WNV disease in Canada, particularly in 2007. Statistical modeling and geographic information systems can be used to develop a predictive model and facilitate the mobilization of targeted disease management strategies. Using data collected between 2005 and 2008, we constructed models integrating abiotic and biotic factors to predict the WNV infection rate in female Culex tarsalis Coquillett, the primary vector of WNV in the Canadian prairies. During the study period, the highest mean Cx. tarsalis infection rate was during week 34 (late August). The Cx. tarsalis infection rate increased with increasing Cx. tarsalis abundance and mean temperature lagged from 1 to 8 wk, but decreased with increasing mean precipitation lagged from 2 to 6 wk. Furthermore, precipitation was a 'distorter variable' that altered the association between Cx. tarsalis abundance and the WNV infection rate. Our model clarified how weather influenced the Cx. tarsalis infection rate in the Canadian prairies, a newly and highly WNV endemic region of North America. An understanding of the role of lagged weather variables was essential for providing sufficient lead time to predict WNV occurrence, and for implementing disease control and prevention strategies. Furthermore, it is a useful tool for assessing the potential effects of future climate change on WNV in areas near its northern distributional limit.

The clustering of health behaviours in Ireland and their relationship with mental health, self-rated health and quality of life.

BACKGROUND: Health behaviours do not occur in isolation. Rather they cluster together. It is important to examine patterns of health behaviours to inform a more holistic approach to health in both health promotion and illness prevention strategies. Examination of patterns is also important because of the increased risk of mortality, morbidity and synergistic effects of health behaviours. This study examines the clustering of health behaviours in a nationally representative sample of Irish adults and explores the association of these clusters with mental health, self-rated health and quality of life. METHODS: TwoStep Cluster analysis using SPSS was carried out on the SLÁN 2007 data (national Survey of Lifestyle, Attitudes and Nutrition, n = 10,364; response rate =62%; food frequency n = 9,223; cluster analysis n = 7,350). Patterns of smoking, drinking alcohol, physical activity and diet were considered. Associations with positive and negative mental health, quality of life and self-rated health were assessed. RESULTS: Six health behaviour clusters were identified: Former Smokers, 21.3% (n = 1,564), Temperate, 14.6% (n = 1,075), Physically Inactive, 17.8% (n = 1,310), Healthy Lifestyle, 9.3% (n = 681), Multiple Risk Factor, 17% (n = 1248), and Mixed Lifestyle, 20% (n = 1,472). Cluster profiles varied with men aged 18-29 years, in the lower social classes most likely to adopt unhealthy behaviour patterns. In contrast, women from the higher social classes and aged 65 years and over were most likely to be in the Healthy Lifestyle cluster. Having healthier patterns of behaviour was associated with positive lower levels of psychological distress and higher levels of energy vitality. CONCLUSION: The current study identifies discernible patterns of lifestyle behaviours in the Irish population which are similar to those of our European counterparts. Healthier clusters (Former Smokers, Temperate and Healthy Lifestyle) reported higher levels of energy vitality, lower levels of psychological distress, better self-rated health and better quality of life. In contrast, those in the Multiple Risk Factor cluster had the lowest levels of energy and vitality and the highest levels of psychological distress. Identification of these discernible patterns because of their relationship with mortality, morbidity and longevity is important for identifying national and international health behaviour patterns.

Social-Emotional Difficulties in Irish Children Aged Five and Nine Years: A National, Longitudinal Study.

A small proportion of children experience social-emotional difficulties from early childhood onwards. Longitudinal studies with nationally representative samples are needed to identify the prevalence and the characteristics of children and families persistently experiencing these difficulties. Secondary analysis of data collected on over 7500 Irish children and with the Strengths and Difficulties Questionnaire as the primary indicator, found that 6% of children when they were five year olds and 8% when they were nine-years, had above threshold scores that warranted further investigation. A smaller proportion-2.9% had elevated scores at both ages. Logistic regression analyses found that children with one or more developmental disabilities were up to six times more likely to have sustained difficulties. There were also significant associations with the lower education attainment of primary caregivers and the socio-economic deprivation of families. Primary caregivers and teachers reported higher conflict in their relationships with these children. Although the number of Irish children presenting with continuing social-emotional difficulties is small, they can present an ongoing and future societal cost in terms of the impact on family relations and demands placed on educational, health and social services. This study identified the children and families who are at greatest risk and for whom targeted early intervention services could be provided.

Passive and Active Surveillance for Ixodes scapularis (Acari: Ixodidae) in Saskatchewan, Canada.

Passive and active surveillance for the blacklegged tick, Ixodes scapularis Say, in the Canadian province of Saskatchewan was conducted over a 9-yr period (2009-2017). More than 26,000 ixodid ticks, representing 10 species, were submitted through passive surveillance. Most (97%) of these were the American dog tick, Dermacentor variabilis (Say). Of the 65 I. scapularis adults submitted, 75% were collected from dogs. Infection rates of Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti in I. scapularis were 12%, 8%, and 0%, respectively. Although the I. scapularis submitted by passive surveillance were collected from five of seven ecoregions in central and southern Saskatchewan, they were most frequent in the Moist Mixed Grassland and Aspen Parklands. In contrast, no I. scapularis were collected from the extensive field sampling conducted at multiple sites in different ecoregions across the province. Hence, there is no evidence of I. scapularis having established a breeding population in Saskatchewan. Nonetheless, continued surveillance for blacklegged ticks is warranted given their important role as a vector of medically and veterinary important pathogens, and because they have recently become established across much of the southern portions of the neighboring province of Manitoba.

The effect of patient-prosthesis mismatch on survival after aortic and mitral valve replacement: a 10 year, single institution experience.

BACKGROUND: The evidence on the impact of patient-prosthesis Mismatch (PPM) on survival thus far has been conflicting. The aim of this study was to 1) study the effect of PPM on survival after isolated aortic and mitral valve replacement and 2) Assess the interaction between left ventricular function and PPM on survival. METHODS: The study cohort was patients who underwent isolated Aortic valve replacement (AVR) and Mitral valve replacement (MVR) over a 10-year period from 2008 to 2018. PPM was defined using the projected indexed effective orifice area (EOAi). The cohort was divided into different groups based on the degree of PPM. The severity of PPM was classified using threshold values of EOAi used in the literature. The Kaplan- Meier method was used to compare survival by degree of PPM. Multivariate Cox proportional hazards models were used to generate adjusted hazard ratios (HR) with 95% confidence intervals. An interactive term for ejection fraction (EF) was added to test whether EF modifies the effect of the PPM grade on survival. In addition, sub-group analysis based on left ventricular function was performed. RESULTS: In the AVR cohort, there were a total of 1953 patients. The distribution of patients in the different PPM categories was as follows: no PPM 59.7%; moderate PPM 36.8%; severe PPM 3.5%. There was no significant difference in survival between the different groups. At 10 years, the adjusted HR between patients with severe PPM versus no PPM was 1.1(CI 0.5-2.4, p >  0.05) and the HR between those with moderate PPM versus no PPM was 0.97 (CI 0.74-1.23, p >  0.05). In the MVR cohort, there were a total of 298 patients. The distribution of PPM is as follows: no PPM 59.4%; and with PPM 40.6%. Again, there was no significant difference in survival between the groups. At 5 years, the adjusted HR between patients with PPM versus no PPM was 1.45 (CI 0.67-3.14, p >  0.05). In both groups, there was no significant interaction between left ventricular function (LVF) and degree of PPM on survival. CONCLUSIONS: In our study cohort, the degree of PPM was not an independent predictor of survival after AVR or MVR. There was also no significant interaction between LV function and degree of PPM on survival.

Mechanical circulatory support for refractory cardiogenic shock post-acute myocardial infarction-a decade of lessons.

BACKGROUND: There are 0.9 catheterization labs per 100,000 inhabitants in Scotland for percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI), which are much less accessible to patients in remote and rural areas. An uncommon but sinister sequalae following AMI is cardiogenic shock (CS) that could be refractory to inotropic support. CS complicates 5-15% of AMIs occurring in ST-segment elevation myocardial infarctions (STEMIs). Outcomes of CS are poor with mortalities of up to 90% reported in the literature in the absence of experienced care. We report our experience as the tertiary referral centre in Scotland for MCS and heart transplantation over 8 years. METHODS: A retrospective review of prospectively collected data was undertaken on all patients registered to the MCS service. The database was interrogated for patient demographics, type of mechanical circulatory support (MCS) and duration of MCS support, PCI-outcomes and survival to 30 days. A time-to-event analysis was performed using patient survival as the primary outcome measure. RESULTS: Twenty-three patients (16 male, 7 females) were included. The median age of the patients as 50 years (range, 45-56 years). VA-ECMO was the initial MCS of choice in 17 (73.9%) patients with BIVAD for 4 (17.4%) patients and LVAD for 2 (8.7%) patients. Thirty-day mortality was 21.8% in this cohort, however survival to discharge was 52.2%. Eleven (47.8%) patients recovered without the need for any further support, however only 9 (81.8%) patients in this subgroup survived to discharge. Three (13.0%) patients received a durable LVAD. In this subgroup, one patient was transplanted whereas two patients died due to complications while on support. The median length of in-hospital MCS support was 4 days. Median in-hospital stay was 27 days. Long-term follow up of up to 8 years demonstrates a high mortality beyond 30-day up to the first 6-month post MCS support. CONCLUSIONS: MCS usage in these patients carries a high mortality in the early post-implantation period. However, there is a significant benefit to patients who survive the initial bridging period to recovery or destination therapy.

Extra-corporeal membrane oxygenation for refractory cardiogenic shock after adult cardiac surgery: a systematic review and meta-analysis.

BACKGROUND: Postcardiotomy cardiogenic shock (PCCS) refractory to inotropic support and intra-aortic balloon pump (IABP) occurs rarely but is almost universally fatal without mechanical circulatory support. In this systematic review and meta-analysis we looked at the evidence behind the use of veno-arterial extra-corporeal membrane oxygenation (VA ECMO) in refractory PCCS from a patient survival rate and determinants of outcome viewpoint. METHODS: A systematic review was performed in January 2017 using PubMed (with no defined time period) using the keywords "postcardiotomy", "cardiogenic shock", "extracorporeal membrane oxygenation" and "cardiac surgery". We excluded papers pertaining to ECMO following paediatric cardiac surgery, medical causes of cardiogenic shock, as well as case reports, review articles, expert opinions, and letters to the editor. Once the studies were collated, a meta-analysis was performed on the proportion of survivors in those papers that met the inclusion criteria. Meta-regression was performed for the most commonly reported adverse prognostic indicators (API). RESULTS: We identified 24 studies and a cumulative pool of 1926 patients from 1992 to 2016. We tabulated the demographic data, including the strengths and weaknesses for each of the studies, outcomes of VA ECMO for refractory PCCS, complications, and APIs. All the studies were retrospective cohort studies. Meta-analysis of the moderately heterogeneous data (95% CI 0.29 to 0.34, p < 0.01, I 2  = 60%) revealed overall survival rate to hospital discharge of 30.8%. Some of the commonly reported APIs were advanced age (>70 years, 95% CI -0.057 to 0.001, P = 0.058), and long ECMO support (95% CI -0.068 to 0.166, P = 0.412). Postoperative renal failure, high EuroSCORE (>20%), diabetes mellitus, obesity, rising lactate whilst on ECMO, gastrointestinal complications had also been reported. CONCLUSION: Haemodynamic support with VA ECMO provides a survival benefit with reasonable intermediate and long-term outcomes. Many studies had reported advanced age, renal failure and prolonged VA ECMO support as the most likely APIs for VA ECMO in PCCS. EuroSCORE can be utilized to anticipate the need for prophylactic perioperative VA ECMO in the high-risk category. APIs can be used to aid decision-making regarding both the institution and weaning of ECMO for refractory PCCS.

A 20-year multicentre outcome analysis of salvage mechanical circulatory support for refractory cardiogenic shock after cardiac surgery.

BACKGROUND: Refractory post-cardiotomy cardiogenic shock (PCCS) is a relatively rare phenomenon that can lead to rapid multi-organ dysfunction syndrome and is almost invariably fatal without advanced mechanical circulatory support (AMCS), namely extra-corporeal membrane oxygenation (ECMO) or ventricular assist devices (VAD). In this multicentre observational study we retrospectively analyzed the outcomes of salvage venoarterial ECMO (VA ECMO) and VAD for refractory PCCS in the 3 adult cardiothoracic surgery centres in Scotland over a 20-year period. METHODS: The data was obtained through the Edinburgh, Glasgow and Aberdeen cardiac surgery databases. Our inclusion criteria included any adult patient from April 1995 to April 2015 who had received salvage VA ECMO or VAD for PCCS refractory to intra-aortic balloon pump (IABP) and maximal inotropic support following adult cardiac surgery. RESULTS: A total of 27 patients met the inclusion criteria. Age range was 34-83 years (median 51 years). There was a large male predominance (n = 23, 85 %). Overall 23 patients (85 %) received VA ECMO of which 14 (61 %) had central ECMO and 9 (39 %) had peripheral ECMO. Four patients (15 %) were treated with short-term VAD (BiVAD = 1, RVAD = 1 and LVAD = 2). The most common procedure-related complication was major haemorrhage (n = 10). Renal failure requiring renal replacement therapy (n = 7), fatal stroke (n = 5), septic shock (n = 2), and a pseudo-aneurysm at the femoral artery cannulation site (n = 1) were also observed. Overall survival to hospital discharge was 40.7 %. All survivors were NYHA class I-II at 12 months' follow-up. CONCLUSION: AMCS for refractory PCCS carries a survival benefit and achieves acceptable functional recovery despite a significant complication rate.

Transport and viability of Escherichia coli cells in clean and iron oxide coated sand following coating with silver nanoparticles.

A mechanistic understanding of processes controlling the transport and viability of bacteria in porous media is critical for designing in situ bioremediation and microbiological water decontamination programs. We investigated the combined influence of coating sand with iron oxide and silver nanoparticles on the transport and viability of Escherichia coli cells under saturated conditions. Results showed that iron oxide coatings increase cell deposition which was generally reversed by silver nanoparticle coatings in the early stages of injection. These observations are consistent with short-term, particle surface charge controls on bacteria transport, where a negatively charged surface induced by silver nanoparticles reverses the positive charge due to iron oxide coatings, but columns eventually recovered irreversible cell deposition. Silver nanoparticle coatings significantly increased cell inactivation during transit through the columns. However, when viability data is normalised to volume throughput, only a small improvement in cell inactivation is observed for silver nanoparticle coated sands relative to iron oxide coating alone. This counterintuitive result underscores the importance of net surface charge in controlling cell transport and inactivation and implies that the extra cost for implementing silver nanoparticle coatings on porous beds coated with iron oxides may not be justified in designing point of use water filters in low income countries.

Revisiting the dimensionality of the Hospital Anxiety and Depression Scale in an international sample of patients with ischaemic heart disease.

OBJECTIVE: Recently controversy has surrounded the dimensionality of the Hospital Anxiety and Depression Scale (HADS). We assessed the dimensionality of the HADS in a large international sample of patients with ischaemic heart disease (IHD) using confirmatory factor analysis (CFA). The analysis of an international sample enabled the current study to broaden knowledge gained from existing studies with small, regional samples. METHODS: Data from the HeartQoL study of patients with IHD (n=6241, 22 countries speaking 15 languages) were analyzed using CFA. RESULTS: CFA indicated a hierarchical bifactor solution, with mostly strong item loadings on a general factor (explaining 73% of the variance), and weak to very weak loadings on orthogonal depression (16%) and anxiety (11%) subscales. The bifactor model fits the data significantly better than both the original bidimensional model and Dunbar's higher-order three-factor model. CONCLUSION: These results, from a large international sample of patients with IHD, suggest that the HADS scale is dominated by a single general distress factor. Although the best CFA model fit was a hierarchical bifactor solution, the subscales had weak item loadings, providing little psychometric evidence of the ability of the HADS to differentiate anxiety and depressive symptoms. It is argued that clinicians and researchers working with patients with IHD should abandon the HADS and use alternative measures of depression and anxiety.

Effectiveness of acupuncture for nonspecific chronic low back pain: a systematic review and meta-analysis.

STUDY DESIGN: A systematic review and meta-analysis of randomized controlled trials (RCTs). OBJECTIVE: To evaluate the totality of evidence in relation to the effectiveness of acupuncture for nonspecific chronic low back pain (NSCLBP). SUMMARY OF BACKGROUND DATA: Acupuncture has become a popular alternative for treating clinical symptoms of NSCLBP. A number of RCTs have examined the effectiveness of acupuncture in the treatment of NSCLBP. METHODS: A systematic literature search was completed without date or language restrictions up to May 2012. Studies included in the review were RCTs that examined all forms of acupuncture that adhered to the Traditional Acupuncture Theory for treating NSCLBP. Outcome measures included impairment, activity limitation, and participation restriction. The methodological quality of the studies was examined using the Cochrane risk of bias tool. RESULTS: Thirty-two studies were included in the systematic review, of which 25 studies presented relevant data for the meta-analysis. Acupuncture had a clinically meaningful reduction in levels of self-reported pain (mean difference =-16.76 [95% confidence interval, -33.33 to -0.19], P = 0.05, I = 90%) when compared with sham, and improved function (standard mean difference =-0.94 [95% confidence interval, -1.41 to -0.47], P < 0.00, I = 78%) when compared with no treatment immediately postintervention. Levels of function also clinically improved when acupuncture in addition to usual care, or electroacupuncture was compared with usual care alone. When acupuncture was compared with medications (NSAIDs, muscle relaxants, and analgesics) and usual care, there were statistically significant differences between the control and the intervention groups but these differences were too small to be of any clinical significance. There was no evidence in support of acupuncture over transcutaneous electrical nerve stimulation. CONCLUSION: This systematic review demonstrates that acupuncture may have a favorable effect on self-reported pain and functional limitations on NSCLBP. However, the results should be interpreted in the context of the limitations identified, particularly in relation to the heterogeneity in the study characteristics and the low methodological quality in many of the included studies. LEVEL OF EVIDENCE: 1.

A whole-hospital approach? Some staff views of a hospital bereavement care service.

A qualitative study was conducted to address staff's views of bereavement care in a large hospital setting. Two focus-groups and 1 interview were attended by 21 self-selected staff. The qualitative analysis yielded the following: (a) a staff training program within a structured bereavement care service may give staff a sense of confidence and pride in this aspect of their work; (b) a whole-hospital approach to bereavement care may offer an alternative model to individual clinical services; (c) the question is raised as to whether the presence of a bereavement co-ordinator helps contain staff anxiety and other painful emotions generated by contact with the dying and bereaved; and (d) the potential role of ancillary staff in bereavement care warrants more study.

Climate change and West Nile virus in a highly endemic region of North America.

The Canadian prairie provinces of Manitoba, Saskatchewan, and Alberta have reported the highest human incidence of clinical cases of West Nile virus (WNV) infection in Canada. The primary vector for WVN in this region is the mosquito Culex tarsalis. This study used constructed models and biological thresholds to predict the spatial and temporal distribution of Cx. tarsalis and WNV infection rate in the prairie provinces under a range of potential future climate and habitat conditions. We selected one median and two extreme outcome scenarios to represent future climate conditions in the 2020 (2010-2039), 2050 (2040-2069) and 2080 (2070-2099) time slices. In currently endemic regions, the projected WNV infection rate under the median outcome scenario in 2050 raised 17.91 times (ranged from 1.29-27.45 times for all scenarios and time slices) comparing to current climate conditions. Seasonal availability of Cx. tarsalis infected with WNV extended from June to August to include May and September. Moreover, our models predicted northward range expansion for Cx. tarsalis (1.06-2.56 times the current geographic area) and WNV (1.08-2.34 times the current geographic area). These findings predict future public and animal health risk of WNV in the Canadian prairie provinces.

Modeling monthly variation of Culex tarsalis (Diptera: Culicidae) abundance and West Nile Virus infection rate in the Canadian Prairies.

The Canadian prairie provinces of Alberta, Saskatchewan, and Manitoba have generally reported the highest human incidence of West Nile virus (WNV) in Canada. In this study, environmental and biotic factors were used to predict numbers of Culex tarsalis Coquillett, which is the primary mosquito vector of WNV in this region, and prevalence of WNV infection in Cx. tarsalis in the Canadian prairies. The results showed that higher mean temperature and elevated time lagged mean temperature were associated with increased numbers of Cx. tarsalis and higher WNV infection rates. However, increasing precipitation was associated with higher abundance of Cx. tarsalis and lower WNV infection rate. In addition, this study found that increased temperature fluctuation and wetland land cover were associated with decreased infection rate in the Cx. tarsalis population. The resulting monthly models can be used to inform public health interventions by improving the predictions of population abundance of Cx. tarsalis and the transmission intensity of WNV in the Canadian prairies. Furthermore, these models can also be used to examine the potential effects of climate change on the vector population abundance and the distribution of WNV.