Haslea silbo, A Novel Cosmopolitan Species of Blue Diatoms.

Specimens of a new species of blue diatoms from the genus Haslea Simonsen were discovered in geographically distant sampling sites, first in the Canary Archipelago, then North Carolina, Gulf of Naples, the Croatian South Adriatic Sea, and Turkish coast of the Eastern Mediterranean Sea. An exhaustive characterization of these specimens, using a combined morphological and genomic approach led to the conclusion that they belong to a single new to science cosmopolitan species, Haslea silbo sp. nov. A preliminary characterization of its blue pigment shows similarities to marennine produced by Haslea ostrearia, as evidenced by UV-visible spectrophotometry and Raman spectrometry. Life cycle stages including auxosporulation were also observed, providing data on the cardinal points of this species. For the two most geographically distant populations (North Carolina and East Mediterranean), complete mitochondrial and plastid genomes were sequenced. The mitogenomes of both strains share a rare atp6 pseudogene, but the number, nature, and positions of the group II introns inside its cox1 gene differ between the two populations. There are also two pairs of genes fused in single ORFs. The plastid genomes are characterized by large regions of recombination with plasmid DNA, which are in both cases located between the ycf35 and psbA genes, but whose content differs between the strains. The two sequenced strains hosts three plasmids coding for putative serine recombinase protein whose sequences are compared, and four out of six of these plasmids were highly conserved.

Three decades of Canadian marine harmful algal events: Phytoplankton and phycotoxins of concern to human and ecosystem health.

Spatial and temporal trends of marine harmful algal events in Canada over the last three decades were examined using data from the Harmful Algal Event Database (HAEDAT). This database contains the most complete record of algal blooms, phycotoxins and shellfish harvesting area closures in Canada since 1987. This 30-year review of 593 Canadian HAEDAT records from 1988 to 2017, together with other Canadian data and publications, shows that recurring harmful algal events have been widespread throughout both the Atlantic and Pacific coastal regions. The 367 paralytic shellfish toxin (PST) reports revealed annual and frequent recurrence throughout both the Atlantic and Pacific regions, including multi-year PST events in the Bay of Fundy, the Estuary and Gulf of St. Lawrence and the Strait of Georgia. The 70 amnesic shellfish toxin (AST) records revealed no recognizable trend, as these events were usually area specific and did not recur annually. The increasing frequency of diarrhetic shellfish toxin (DST) events over the period of this review, in total 59 records, can be at least partially explained by increased sampling effort. Marine species mortalities caused by harmful algae (including diatoms, dictyochophytes, dinoflagellates, and raphidophytes), were a common occurrence in the Pacific region (87 reports), but have been reported much less frequently in the Atlantic region (10 reports). Notable Canadian records contained in HAEDAT include the first detection worldwide of amnesic shellfish poisoning (ASP), attributed to the production of domoic acid (an AST) by a diatom (Pseudo-nitzschia multiseries) in Prince Edward Island in 1987. The first proven case of diarrhetic shellfish poisoning (DSP) in Canada and North America was recorded in 1990, and the first closures of shellfish harvesting due to DST (associated with the presence of Dinophysis norvegica) occurred in Nova Scotia in 1992, followed by closures in Newfoundland and Labrador in 1993. In 2008, mass mortalities of fishes, birds and mammals in the St. Lawrence Estuary were caused by Alexandrium catenella and high levels of PST. During 2015, the Pacific coast experienced a large algal bloom that extended from California to Alaska. It resulted in the closure of several shellfish harvesting areas in British Columbia due to AST, produced by Pseudo-nitzschia australis. Data from the Canadian Arctic coast is not included in HAEDAT. However, because of the emerging importance of climate change and increased vessel traffic in the Arctic, information on the occurrence of harmful algal species (pelagic and sympagic = sea ice-associated) in that region was compiled from relevant literature and data. The results suggest that these taxa may be more widespread than previously thought in the Canadian Arctic. Information in HAEDAT was not always robust or complete enough to provide conclusions about temporal trends. Compilation of spatial and temporal information from HAEDAT and other records is nevertheless important for evaluating the potential role of harmful algae as a stressor on Canadian marine ecosystems, and will support the next step: developing a knowledge gap analysis that will establish research priorities for determining their consequences on human and ecosystem health.

Phylogenetic Relationships and Biogeography of the Diatom Genus Mastogloia (Bacillariophyceae): Revision of the Section Ellipticae Including the Description of New Taxa.

Benthic diatoms represent an important component of aquatic ecosystems, both for their contribution to primary production and their role in the marine food web. Mastogloia is a large, mostly marine diatom genus occurring in microphytobenthic communities of temperate to tropical coastal regions. In this study, the phylogenetic relationships, based on cladistic methodologies using morphological features, among all taxa belonging to the genus Mastogloia section Ellipticae (i.e., 33 taxa) were investigated using the parsimony method. The character states that describe variations of central area, raphe, areola vela and partectal position have a tendency to be very homologous and useful in recovering phylogenies. The typical character states of this section, such as rounded apices represents an ancestral homology. The phylogenetic hypothesis supports the probable monophyletic origin of the section Ellipticae (synapomorphy). Moreover, we completed the taxonomical review of the section Ellipticae, with the description of seven species, M. cocconeiformis, M. cribrosa, M. fimbriata, M. ovata, M. pseudolatecostata, and of two species new to science, M. rosalbae and M. aegyptiaca. Finally, this study provides historical and new information on the geographical distribution of Mastogloia species.

Pluri-annual sediment budget in a navigated river system: the Seine River (France).

This study aims at quantifying pluri-annual Total Suspended Matter (TSM) budgets, and notably the share of river navigation in total re-suspension at a long-term scale, in the Seine River along a 225 km stretch including the Paris area. Erosion is calculated based on the transport capacity concept with an additional term for the energy dissipated by river navigation. Erosion processes are fitted for the 2007-2011 period based on i) a hydrological typology of sedimentary processes and ii) a simultaneous calibration and retrospective validation procedure. The correlation between observed and simulated TSM concentrations is higher than 0.91 at all monitoring stations. A variographic analysis points out the possible sources of discrepancies between the variabilities of observed and simulated TSM concentrations at three time scales: sub-weekly, monthly and seasonally. Most of the error on the variability of simulated concentrations concerns sub-weekly variations and may be caused by boundary condition estimates rather than modeling of in-river processes. Once fitted, the model permits to quantify that only a small fraction of the TSM flux sediments onto the river bed (<0.3‰). The river navigation contributes significantly to TSM re-suspension in average (about 20%) and during low flow periods (over 50%). Given the significant impact that sedimentary processes can have on the water quality of rivers, these results highlight the importance of taking into account river navigation as a source of re-suspension, especially during low flow periods when biogeochemical processes are the most intense.

Large, omega-3 rich, pelagic diatoms under Arctic sea ice: sources and implications for food webs.

Pelagic primary production in Arctic seas has traditionally been viewed as biologically insignificant until after the ice breakup. There is growing evidence however, that under-ice blooms of pelagic phytoplankton may be a recurrent occurrence. During the springs of 2011 and 2012, we found substantial numbers (201-5713 cells m-3) of the large centric diatom (diameter >250 µm) Coscinodiscus centralis under the sea ice in the Canadian Arctic Archipelago near Resolute Bay, Nunavut. The highest numbers of these pelagic diatoms were observed in Barrow Strait. Spatial patterns of fatty acid profiles and stable isotopes indicated two source populations for C. centralis: a western origin with low light conditions and high nutrients, and a northern origin with lower nutrient levels and higher irradiances. Fatty acid analysis revealed that pelagic diatoms had significantly higher levels of polyunsaturated fatty acids (mean ± SD: 50.3 ± 8.9%) compared to ice-associated producers (30.6 ± 10.3%) in our study area. In particular, C. centralis had significantly greater proportions of the long chain omega-3 fatty acid, eicosapentaenoic acid (EPA), than ice algae (24.4 ± 5.1% versus 13.7 ± 5.1%, respectively). Thus, C. centralis represented a significantly higher quality food source for local herbivores than ice algae, although feeding experiments did not show clear evidence of copepod grazing on C. centralis. Our results suggest that C. centralis are able to initiate growth under pack ice in this area and provide further evidence that biological productivity in ice-covered seas may be substantially higher than previously recognized.

Experimental study of 112 Gb/s short reach transmission employing PAM formats and SiP intensity modulator at 1.3 µm.

We present a Silicon Photonic (SiP) intensity modulator operating at 1.3 µm with pulse amplitude modulation formats for short reach transmission employing a digital to analog converter for the RF signal generator, enabling pulse shaping and precompensation of the transmitter's frequency response. Details of the SiP Mach-Zehnder interfometer are presented. We study the system performance at various bit rates, PAM orders and propagation distances. To the best of our knowledge, we report the first demonstration of a 112 Gb/s transmission over 10 km of SMF fiber operating below pre-FEC BER threshold of 3.8 × 10(-3) employing PAM-8 at 37.4 Gbaud using a fully packaged SiP modulator. An analytical model for the Q-factor metric applicable for multilevel PAM-N signaling is derived and accurately experimentally verified in the case of Gaussian noise limited detection. System performance is experimentally investigated and it is demonstrated that PAM order selection can be optimally chosen as a function of the desired throughput. We demonstrate the ability of the proposed transmitter to exhibit software-defined transmission for short reach applications by selecting PAM order, symbol rate and pulse shape.

Analytical and experimental performance evaluation of an integrated Si-photonic balanced coherent receiver in a colorless scenario.

We study analytically and experimentally the performance limits of a Si-photonic (SiP) balanced coherent receiver (CRx) co-packaged with transimpedance amplifiers (TIAs) in a colorless WDM scheme. Firstly, the CRx architecture is depicted and characterization results are presented. Secondly, an analytical expression for the signal-to-noise ratio (SNR) at the CRx output is rigorously developed and various noise sources in the context of colorless reception are outlined. Thirdly, we study experimentally the system-level CRx performance in colorless reception of 16 × 112 Gbps PDM-QPSK WDM channels. Using a 15.5 dBm local oscillator (LO) power, error free transmissions over 4800 and 4160 km at received powers of -3 and -21 dBm per channel, respectively, were achieved in a fully colorless and preamplifierless reception. Next, a set of measurements on one of the center WDM channels is performed where the LO power, received signal power, distance, and number of channels presented to the CRx are swept to evaluate the performance limits of colorless reception. Results reveal that the LO beating with optical noise incoming with the signal is a dominant noise source regardless of received signal power. In the high received signal power regime (~0 dBm/channel), the self-beat noise from out-of-band (OOB) channels is an additional major noise source especially for small LO-to-signal power ratio, short reach and large number of OOB channels. For example, at a received signal power of 0 dBm/channel after 1600 km transmission, the SNR difference between the fully filtered and colorless scenarios, where 1 and 16 channels are passed to the CRx respectively, grows from 0.5 to 3.3 dB as the LO power changes from 12 to 0 dBm. For low received power (~-12 dBm/channel), the effect of OOB channels becomes minor while the receiver shot and thermal noises become more significant. We identify the common mode rejection ratio (CMRR) and sensitivity as the two important CRx specifications that impact the performance at high and low received signal power regimes, respectively. Finally, an excellent match between experimental and analytical SNRs is proven after the derived SNR model is fitted to the experimental data in a least-squares sense. The model is then used to predict that the CRx can operate colorlessly for a fully populated WDM spectrum with 80 channels provided that the LO-to-signal power ratio is properly set.

Hydrological modelling of Toxoplasma gondii oocysts transport to investigate contaminated snowmelt runoff as a potential source of infection for marine mammals in the Canadian Arctic.

Toxoplasma gondii (T. gondii) is a zoonotic protozoan that sometimes causes serious illness in humans and other animals worldwide, including the Canadian Arctic. Wild and domestic felids, the only hosts able to shed T. gondii oocysts, are practically non-existent in the Canadian Arctic. So here the hypothesis that T. gondii oocysts, shed in the southern areas of the boreal watershed, could contaminate the Arctic coastal marine environment via surface runoff, particularly during the spring snowmelt period, was explored. A watershed model was applied to simulate the hydrological transport of T. gondii oocysts during the snowmelt period and test the possible efficiency of river-to-sea transport as a potential source of marine organisms' exposure to this pathogen. Simulations were run for two pilot watersheds with the ultimate aim of extrapolating the results across the Canadian Arctic watersheds. Results suggest that daily stream flow concentrations of T. gondii oocysts at the river outlet are likely to be very low. However, accumulation of oocysts in the estuarine areas may be large enough to contaminate estuarine/marine filter-feeding molluscs and snails on which seals and other marine mammals may feed. Potential maximum concentrations of T. gondii oocysts in runoff are reached at the beginning of the snowmelt period with maxima varying with discharge rates into rivers and how far upstream oocysts are discharged. Meteorological conditions during the snowmelt period can affect simulated concentrations of oocysts. These findings support the hypothesis that T. gondii oocysts carried in snowmelt runoff could be a source of T. gondii infection for marine mammals in the Canadian Arctic, and for Arctic human populations that hunt and consume raw meat from marine mammals.

Fate and transport of Toxoplasma gondii oocysts in seasonally snow covered watersheds: a conceptual framework from a melting snowpack to the Canadian arctic coasts.

Toxoplasma gondii is a zoonotic protozoan that causes serious illness in humans and infects animals worldwide, including the Canadian Arctic. Indeed, high prevalence of infection amongst Inuit has been recorded, possibly due to consumption of raw infected seal meat. Here we explore the hypothesis that T. gondii oocysts contaminate the coastal marine environment via surface runoff from across the boreal watershed, particularly during the snowmelt period. We propose a conceptual framework of the different processes governing the fate and transport of T. gondii oocysts from the melting snowpack to the Canadian arctic coast via the freshwater runoff. This framework identifies the feasibility of a transmission pathway of oocysts from contaminated soil to the marine environment, but also the complexity and multiplicity of mechanisms involved. In addition, the framework identifies knowledge gaps for guiding future studies on T. gondii oocysts. Furthermore, this work could be used as a tool to investigate the possible estuarine contamination by other faeces-borne pathogens transported via the spring freshet in seasonally snow covered watersheds.

Spatiotemporal dynamics of Toxoplasma gondii infection in Canadian lynx (Lynx canadensis) in western Québec, Canada.

Toxoplasma gondii, one of the more common zoonotic parasites in the world, can cause serious illness in humans and other animals worldwide. Felids are the only known host that can shed T. gondii oocysts, which are essential to the perpetuation of the parasite. In much of boreal Canada, the Canadian lynx (Lynx canadensis) is the only wild felid host that could contribute to environmental contamination with T. gondii oocysts. We estimated the prevalence of T. gondii antibodies in Canadian lynx from western Québec and compared our results with earlier findings in the same region 12 yr earlier. We investigated factors associated with seroconversion, including age, sex, geographic location, and possible co-occurrence with domestic cats (Felis catus), and we assessed the proportion of lynx shedding T. gondii oocysts. Blood and fecal samples were collected from 84 lynx harvested by trappers in the eastern part of the study area during winter 2009-2010. Sera were tested for antibodies to T. gondii by the modified agglutination test (cutoff titer 1:50) and fecal samples for parasite eggs by fecal flotation. Antibodies to T. gondii were detected in sera of 14% of 84 lynx. Numerous helminth ova and coccidian oocysts were found in feces, whereas T. gondii-like oocysts were not detected. Antibody prevalence increased with age class (odds ratio [OR]=4.33, 95% confidence interval [CI]=1.57-11.99, P<0.01). Antibody prevalence (14%) in our study was significantly lower than in 84 lynx (36%) trapped in the western part of the study area during winter 1997-1998 (OR=0.18, 95% CI=0.08-0.44, P<0.001). Our results suggest there may be significant spatiotemporal dynamics of T. gondii infection in lynx in Canada, and we review possible abiotic and biotic ecologic factors supporting these findings.

Conceptual evaluation of population health surveillance programs: method and example.

Veterinary and public health surveillance programs can be evaluated to assess and improve the planning, implementation and effectiveness of these programs. Guidelines, protocols and methods have been developed for such evaluation. In general, they focus on a limited set of attributes (e.g., sensitivity and simplicity), that are assessed quantitatively whenever possible, otherwise qualitatively. Despite efforts at standardization, replication by different evaluators is difficult, making evaluation outcomes open to interpretation. This ultimately limits the usefulness of surveillance evaluations. At the same time, the growing demand to prove freedom from disease or pathogen, and the Sanitary and Phytosanitary Agreement and the International Health Regulations require stronger surveillance programs. We developed a method for evaluating veterinary and public health surveillance programs that is detailed, structured, transparent and based on surveillance concepts that are part of all types of surveillance programs. The proposed conceptual evaluation method comprises four steps: (1) text analysis, (2) extraction of the surveillance conceptual model, (3) comparison of the extracted surveillance conceptual model to a theoretical standard, and (4) validation interview with a surveillance program designer. This conceptual evaluation method was applied in 2005 to C-EnterNet, a new Canadian zoonotic disease surveillance program that encompasses laboratory based surveillance of enteric diseases in humans and active surveillance of the pathogens in food, water, and livestock. The theoretical standard used for evaluating C-EnterNet was a relevant existing structure called the "Population Health Surveillance Theory". Five out of 152 surveillance concepts were absent in the design of C-EnterNet. However, all of the surveillance concept relationships found in C-EnterNet were valid. The proposed method can be used to improve the design and documentation of surveillance programs. It complements existing surveillance evaluation methods. Conceptual evaluation is not a performance-oriented evaluation method and so it is particularly useful for surveillance programs with a valid conceptual framework but limited technical capacity and resources. Such programs would be penalized using existing performance-based evaluation methods. Applying conjointly the conceptual evaluation along with existing performance-oriented evaluation methods will better judge the worth of surveillance programs. We recommend developing a comprehensive surveillance evaluation framework for veterinary and public health surveillance programs that integrates all existing surveillance evaluation tools and provides an appropriate way to evaluate various types of surveillance programs.

Protists in Arctic drift and land-fast sea ice.

Global climate change is having profound impacts on polar ice with changes in the duration and extent of both land-fast ice and drift ice, which is part of the polar ice pack. Sea ice is a distinct habitat and the morphologically identifiable sympagic community living within sea ice can be readily distinguished from pelagic species. Sympagic metazoa and diatoms have been studied extensively since they can be identified using microscopy techniques. However, non-diatom eukaryotic cells living in ice have received much less attention despite taxa such as the dinoflagellate Polarella and the cercozoan Cryothecomonas being isolated from sea ice. Other small flagellates have also been reported, suggesting complex microbial food webs. Since smaller flagellates are fragile, often poorly preserved, and are difficult for non-experts to identify, we applied high throughput tag sequencing of the V4 region of the 18S rRNA gene to investigate the eukaryotic microbiome within the ice. The sea ice communities were diverse (190 taxa) and included many heterotrophic and mixotrophic species. Dinoflagellates (43 taxa), diatoms (29 taxa) and cercozoans (12 taxa) accounted for ~80% of the sequences. The sympagic communities living within drift ice and land-fast ice harbored taxonomically distinct communities and we highlight specific taxa of dinoflagellates and diatoms that may be indicators of land-fast and drift ice.

A population health surveillance theory.

OBJECTIVES: Despite its extensive use, the term "Surveillance" often takes on various meanings in the scientific literature pertinent to public health and animal health. A critical appraisal of this literature also reveals ambiguities relating to the scope and necessary structural components underpinning the surveillance process. The authors hypothesized that these inconsistencies translate to real or perceived deficiencies in the conceptual framework of population health surveillance. This paper presents a population health surveillance theory framed upon an explicit conceptual system relative to health surveillance performed in human and animal populations. METHODS: The population health surveillance theory reflects the authors' system of thinking and was based on a creative process. RESULTS: POPULATION HEALTH SURVEILLANCE INCLUDES TWO BROAD COMPONENTS: one relating to the human organization (which includes expertise and the administrative program), and one relating to the system per se (which includes elements of design and method) and which can be viewed as a process. The population health surveillance process is made of five sequential interrelated steps: 1) a trigger or need, 2) problem formulation, 3) surveillance planning, 4) surveillance implementation, and 5) information communication and audit. CONCLUSIONS: The population health surveillance theory provides a systematic way of understanding, organizing and evaluating the population health surveillance process.

MORPHOLOGICAL STUDIES OF SOME MARINE MASTOGLOIA (BACILLARIOPHYCEAE) BELONGING TO SECTION SULCATAE, INCLUDING THE DESCRIPTION OF NEW SPECIES.

Epiphytic diatoms on seagrass and seaweed were collected from tropical (e.g., Siladen Island, Celebes Sea, Indonesia and Phú Bài, China Sea, Vietnam), subtropical (e.g., Sharm el-Sheikh, Red Sea, Egypt), and temperate regions (e.g., Patmos Island, Greece) in 2000, 2005, and 2006. Eight species of Mastogloia, belonging to the section Sulcatae, are described mainly through scanning electron microscopy, including two new species to science, M. oculoides and M. sergiana. These species show a differently shaped median depression on the external valve face between the raphe-sternum and the valve margin. Moreover, they lack a developed conopeum or pseudoconopeum, which covers the median depression in other species of the section Sulcatae. This study gives new insights on the ultrastructure of the Mastogloia's valves and provides an update of their current geographical distribution.

From sea to sea: Canada's three oceans of biodiversity.

Evaluating and understanding biodiversity in marine ecosystems are both necessary and challenging for conservation. This paper compiles and summarizes current knowledge of the diversity of marine taxa in Canada's three oceans while recognizing that this compilation is incomplete and will change in the future. That Canada has the longest coastline in the world and incorporates distinctly different biogeographic provinces and ecoregions (e.g., temperate through ice-covered areas) constrains this analysis. The taxonomic groups presented here include microbes, phytoplankton, macroalgae, zooplankton, benthic infauna, fishes, and marine mammals. The minimum number of species or taxa compiled here is 15,988 for the three Canadian oceans. However, this number clearly underestimates in several ways the total number of taxa present. First, there are significant gaps in the published literature. Second, the diversity of many habitats has not been compiled for all taxonomic groups (e.g., intertidal rocky shores, deep sea), and data compilations are based on short-term, directed research programs or longer-term monitoring activities with limited spatial resolution. Third, the biodiversity of large organisms is well known, but this is not true of smaller organisms. Finally, the greatest constraint on this summary is the willingness and capacity of those who collected the data to make it available to those interested in biodiversity meta-analyses. Confirmation of identities and intercomparison of studies are also constrained by the disturbing rate of decline in the number of taxonomists and systematists specializing on marine taxa in Canada. This decline is mostly the result of retirements of current specialists and to a lack of training and employment opportunities for new ones. Considering the difficulties encountered in compiling an overview of biogeographic data and the diversity of species or taxa in Canada's three oceans, this synthesis is intended to serve as a biodiversity baseline for a new program on marine biodiversity, the Canadian Healthy Ocean Network. A major effort needs to be undertaken to establish a complete baseline of Canadian marine biodiversity of all taxonomic groups, especially if we are to understand and conserve this part of Canada's natural heritage.

Geographical variation of Crohn's disease residual incidence in the Province of Quebec, Canada.

BACKGROUND: Crohn's disease (CD) is clinically expressed as a chronic affection of the gastrointestinal tract currently known to have a multifactorial etiology involving a complex pathophysiological host response modulated by genetic susceptibilities, demographic determinants and environmental factors. With more than 20 cases per 100,000 person-years, the province of Quebec, Canada is among regions of the world with highest reported occurrence of CD in relation to other places where comparable estimates are available. This ecological study was designed to provide a medium-scale spatial exploration of CD incidence after accounting for the influence of known population and regional determinants. Health records of consulting patients in southern Quebec were compiled from 1995 to 2000 and used to estimate age and sex standardized rates per health area (n = 156). Various statistical models taking into account the regional effect of Jewish ethnicity, aboriginal ancestry, material deprivation, prescription for oral contraceptives, reportable enteric infection incidence, smoking as well as latitude and longitude locations were fitted. RESULTS: The final regression model presented a coefficient of determination of 22.8% and there was evidence of an eastern trend in the residual incidence (p = 0.018). Overall, the smoothed residual incidence presented a heterogeneous spatial pattern with evidence of patches (multiple health areas) of high, low and contrasting values. Health areas with most extreme incidence residuals where also distributed over the whole province including one area in the metropolitan area of Montreal and others in surrounding areas. CONCLUSIONS: These findings suggest that known populational and regional factors derived through census information only explain a limited fraction of the geographical variation of CD incidence and lead to speculate that the effects of these factors may be incompletely captured (imperfect construction of proxy variables) or that other important factors remain unmeasured. In this view, markers of genetic profiles of homogeneous sub-populations, and other factors linked to agroenvironmental microbial exposure should be further investigated. Once accounting for known factors, it would also be worth comparing adjacent geographical areas demonstrating abrupt changes in residual incidence rates to further explore effect linked to regional factors from those resulting from various reporting systems.

Risk factors associated with West Nile virus mortality in American Crow populations in Southern Quebec.

Soon after the appearance of West Nile virus (WNV) in North America, a number of public health authorities designated the American Crow (Corvus brachyrhynchos) a sentinel for WNV detection. Although preliminary studies have suggested a positive association between American Crow mortality and increased risk of WNV infection in humans, we still know little about dynamic variation in American Crow mortality, both baseline levels and mortality associated with WNV. We hypothesized that the complex social behavior of American Crows, which is shaped by age and seasonal factors, influences both baseline mortality and WNV mortality in American Crow populations. We examined American Crow mortality data from Quebec for the 2005 WNV surveillance year, which lasted from 5 June to 17 September 2005. The variables of interest were age, gender, body condition index, time of year, and land cover. We used a log-linear model to examine baseline mortality. Logistic regression and general linear regression models were constructed to examine variables associated with mortality due to WNV. We found that both age and time of year were key variables in explaining baseline mortality. These two variables were also risk factors for WNV mortality. The probability that a carcass tested positive for WNV increased with the age of the dead bird and as summer progressed. WNV-positive carcasses also had a lower body condition index than WNV-negative carcasses. We believe that the first major wave of American Crow mortality observed in the early summer of 2005 was the result of natural mortality among young American Crows. Because this mortality was not linked to WNV, it appears that American Crow may not be a good species for early detection of WNV activity. Our data also suggest that second-year American Crows play a major role in propagating WNV during their movements to urban land covers during midsummer.

Performance of balanced detection in a coherent receiver.

The quality of balanced detection in a coherent receiver is analyzed theoretically and experimentally. The impact of the characteristics of the optics on the balanced detection is presented. A parameter that characterizes the performance of the balanced detection suitable for the whole optical front-end is propose.

Epidemiology of Crohn's disease in Québec, Canada.

BACKGROUND: Crohn's disease (CD) is an idiopathic inflammatory bowel disease (IBD). We aimed to determine the prevalence and incidence of CD in Québec and characterize the demographic and health-related factors associated with this disease. METHODS: We identified CD cases in the provincial administrative databases for the years 1993-2002. The CD prevalence and incidence rates were estimated respectively for the periods 1993-2002 and 1998-2000. We validated the identified cases using clinically confirmed IBD cases. Predictor variables of CD were analyzed using the Poisson regression model to explain the variation in CD incidence rates across Québec. RESULTS: In all, 21,172 patients fulfilled the CD case definition for the period. The age and sex standardized average prevalence rate for 1993-2002 was 189.7 cases / 100,000 population and the age and sex standardized incidence rate of CD for the 1998-2000 period was 20.2 cases / 100,000 person-years. The female/male cases ratio among incident cases was 0.74 for the 0-14-year-old group, 1.30 for the 15-64-year-old group, and 1.77 for the cases older than 65 years old. After adjustment, independent predictors of CD incidence were: incidence of 5 reportable enteric diseases, proportion of individuals of Jewish ethnicity, and proportion of immigrant people. CONCLUSIONS: The identified predictors of CD explained 20% of the regional variance in the incidence rate of CD in the Québec population. Other factors such as genetic susceptibility to CD or the effect of an environmental cause should be taken into consideration in the models to explain the residual variance.

Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change.

BACKGROUND: Lyme disease is the commonest vector-borne zoonosis in the temperate world, and an emerging infectious disease in Canada due to expansion of the geographic range of the tick vector Ixodes scapularis. Studies suggest that climate change will accelerate Lyme disease emergence by enhancing climatic suitability for I. scapularis. Risk maps will help to meet the public health challenge of Lyme disease by allowing targeting of surveillance and intervention activities. RESULTS: A risk map for possible Lyme endemicity was created using a simple risk algorithm for occurrence of I. scapularis populations. The algorithm was calculated for each census sub-division in central and eastern Canada from interpolated output of a temperature-driven simulation model of I. scapularis populations and an index of tick immigration. The latter was calculated from estimates of tick dispersion distances by migratory birds and recent knowledge of the current geographic range of endemic I. scapularis populations. The index of tick immigration closely predicted passive surveillance data on I. scapularis occurrence, and the risk algorithm was a significant predictor of the occurrence of I. scapularis populations in a prospective field study. Risk maps for I. scapularis occurrence in Canada under future projected climate (in the 2020s, 2050s and 2080s) were produced using temperature output from the Canadian Coupled Global Climate Model 2 with greenhouse gas emission scenario enforcing 'A2' of the Intergovernmental Panel on Climate Change. CONCLUSION: We have prepared risk maps for the occurrence of I. scapularis in eastern and central Canada under current and future projected climate. Validation of the risk maps provides some confidence that they provide a useful first step in predicting the occurrence of I. scapularis populations, and directing public health objectives in minimizing risk from Lyme disease. Further field studies are needed, however, to continue validation and refinement of the risk maps.