Areas Of British Columbia Research Articles

The Prevalence of Hepatitis A in Children in British Columbia

The risk of hepatitis A virus (HAV) infection during childhood is difficult to estimate without population serosurveys because HAV-related symptoms are often mild at this age. Few serosurveys have been conducted in Canada. The present study surveyed teenagers in two nonurban regions of British Columbia where the historical rate of reported HAV either exceeded (region A) or was less than (region B) the historical provincial rate. A point prevalence survey of salivary HAV-specific immunoglobulin G was conducted in high schools among grade 9 students in regions A and B. A questionnaire was used to gather sociodemographic data. The survey was extended to grade 1 and grade 5 students in community 1 of region B. Associations between risk factors and prior infection were evaluated by logistic regression. Eight hundred eleven grade 9 students were tested. Antibody to HAV was detected in 4.7% of students in region A (95% CI 2.9% to 7.2%) and 9.6% of students in region B (95% CI 6.9% to 12.9%). The region B figure reflected HAV antibody prevalence rates of 19.5% in community 1 and 2.5% in the remainder of the region. Younger students in community 1 had low HAV antibody to HAV prevalence rates (3.9% for grade 1 and 3.1% for grade 5), and positive tests in this community were associated with a particular school, foreign travel and brief residence. The risk factors for HAV infection in grade 9 students were not determined. Children in nonurban areas of British Columbia are generally at low risk of HAV infection during the first decade of life regardless of the reported population rates, thereby permitting the consideration of school-based HAV immunization programs.

Effect of periodic letters on evidence-based drug therapy on prescribing behaviour: a randomized trial

The effect of regular and expected printed educational materials on physician prescribing behaviour has not been studied. We sought to measure the impact of a series of evidence-based drug therapy letters mailed to physicians in British Columbia on prescribing to newly treated patients. A paired, cluster randomized community design was used. The study population included 499 physicians from 24 local health areas in British Columbia. Local health areas were paired by number of physicians, and 1 of each pair was randomly selected and its physicians assigned to an intervention group or a control group. The intervention was 12 issues of an evidence-based series called Therapeutics Letter. Physicians in the control group (n = 241) received the letters 3-8 months after physicians in the intervention group (n = 258). The impact on prescribing to newly treated patients (defined as patients who had not previously made a claim for any medication from the class of drugs profiled in the letter) was analyzed using the drug claims database of BC Pharmacare, a publicly funded drug benefits program that covered all seniors and people receiving social assistance. The probability of prescribing a drug recommended in the Therapeutics Letter rather than another drug in the same class increased by 30% in the 3 months after the mailing of the letter relative to the preceding 3 months, adjusted for any before-after changes in the control group (relative risk 1.30; 95% confidence interval 1.13-1.52). No letter achieved statistical significance on its own. However, 11 of the 12 letters produced prescribing changes in the predicted direction such that the overall result was significant when their effect was combined. The combined effect of an ongoing series of printed letters distributed from a credible and trusted source can have a clinically significant effect on prescribing to newly treated patients.

Uncontrolled field performance of Televilt GPS-Simplex™ collars on grizzly bears in western and northern Canada

Commercially available telemetry collars for wildlife that employ Global Positioning System (GPS) devices generally have the ability to gather a large volume of precise location data. We appraised the performance of 12-channel Televilt GPS-SimplexTM collars (Televilt/TVP Positioning AB, Lindesberg, Sweden) deployed across western and northern Canada on grizzly bears (Ursus arctos). Of 71 collar deployments between 2000 and 2002, 38 were retrieved and performed according to their programmed schedule, 20 were retrieved and had some degree of failure, and 13 experienced catastrophic failures and were not retrieved. In addition to these deployments, 10 collars failed predeployment. GPS collar fix success rates were greater for the retrieved collars from the Northwest Territories than for the 4 study areas in British Columbia and Alberta (F4, 50 = 10.82, P < 0.001); thus, the latter areas were grouped for further analyses. Collar fix success rates in the British Columbia and Alberta study areas differed between the retrieved collars that functioned normally (x̄ = 65%, SE = 2.3, n = 28) and collars retrieved with failure events (x̄ = 56%, SE = 4.3, n = 17; t43 = 2.09, P = 0.043). Fix success rates were lower the longer collars were in the field (rs = −0.35, n = 45, P = 0.020). Locations from the GPS collars had a mean dilution of precision of <4 for 2D and 3D locations and thus had a good degree of precision. We were satisfied with the volume and quality of the location data; however, we advise other researchers that significant time and money may be lost troubleshooting problems with the Televilt Simplex system. Other recommendations for future and current users are considered.

Bayesian spatial and ecological models for small-area accident and injury analysis

In this article, recently developed Bayesian spatial and ecological regression models are applied to analyse small-area variation in accident and injury. This study serves to demonstrate how Bayesian modelling techniques can be implemented to assess potential risk factors measured at group (e.g. area) level. Presented here is a unified modelling framework that enables thorough investigations into associations between injury rates and regional characteristics, residual variation and spatial autocorrelation. Using hospital separation data for 83 local health areas in British Columbia (BC), Canada, in 1990–1999, we explore and examine ecological/contextual determinants of motor vehicle accident injury (MVAI) among male children and youth aged 0–24 and for those of six age groups (<1, 1–4, 5–9, 10–14, 15–19 and 20–24). Eighteen local health area characteristics are studied. They include a broad spectrum of socio-economic indicators, residential environment indicators (roads and parks), medical services availability and utilisation, population health, proportion of recent immigrants, crime rates, rates of speeding charge and rates of seatbelt violation. Our study indicates a large regional variation in MVAI in males aged 0–24 in British Columbia, Canada, in 1990–1999, and that adjusting for appropriate risk factors eliminates nearly all the variation observed. Socio-economic influence on MVAI was profoundly apparent in young males of all ages with the injury being more common in communities of lower socio-economic status. High adult male crime rates were significantly associated with high injury rates of boys aged 1–14. Seatbelt violations and excess speeding charges were found to be positively associated with the injury rates of young men aged 20–24. This and similar ecological studies shed light on reasons for regional variations in accident occurrence as well as in the resulting injuries and hospital utilisation. Thereby they are potentially useful in identifying priority areas for injury/accident prevention and in informing regional health planning and policy development.

Copper and health status of cattle grazing high-molybdenum forage from a reclaimed mine tailing site

High concentrations (21–44 mg kg-1 dry matter) of Mo have been identified in forage in several reclaimed mining areas in British Columbia. Since Mo concentrations greater than 5 mg kg-1 in forage dry matter may result in molybdenosis because of a secondary Cu deficiency in ruminants, a study was undertaken to determine if cattle can safely graze the reclaimed land. For 12-wk grazing periods in 1994, 1995 and 1996, 32 cow/calf pairs grazed high-Mo forage at a reclaimed mine tailings site located at the Highland Valley Copper mine near Logan lake, BC. Half of the animals in the trial received a Cu supplement (All-Trace copper bolus) and the other half served as a control group. There were no significant differences (P &lt; 0.05) in weight gain, liver Mo, serum Cu and Mo, and milk Cu and Mo between the two treatment groups of cows. Liver Cu was higher for the Cu bolus group at certain time periods in 1994 and 1995, indicating that the bolus was effective at supplying Cu. At all times, the liver Cu levels for the animals remained above the recommended critical level of 25 mg kg-1 dry matter. Animals appeared healthy and no signs of Cu deficiency were observed. Key words: Molybdenum, molybdenosis, copper, mine tailings, reclamation, animal health

Virulence of Puccinia striiformis f. sp. tritici, cause of stripe rust on wheat, in western Canada from 1984 to 2002

Fifty-seven isolates of Puccinia striiformis f. sp. tritici, causing stripe rust on wheat, were collected in western Canada from 1984 to 2002. The virulence of these isolates was tested on the 17 World and European differentials as well as 7 supplemental differentials. Thirty-nine races were identified. Before 2000, races virulent on wheat ‘Lee’ (Yr7, Yr22, Yr23) and ‘Owens’ mainly originated from Creston, British Columbia, while most of the races from the prairies were avirulent on these two cultivars. New races detected in Canada since 2000 were virulent on both ‘Compair’ (Yr8, Yr19) and ‘Clement’ (Yr9, YrCle). Race 33 (238E150) was repeatedly detected from 2000 to 2002, and other new races had a virulence spectrum that was similar to that of race 33. Some of the prevalent races of stripe rust in the prairie provinces were also detected in the Creston area of British Columbia, suggesting a possible link in the source of inoculum between these two areas. None of the races were virulent on Triticum spelta var. album (Yr5). ‘Chinese 166’ (Yr1), ‘Moro’ (Yr10, YrMor), ‘Hybrid 46’ (Yr3b, Yr4b), Triticum dicoccoides selection G-25 (Yr15), and ‘Spalding Prolific’ (YrSP) were resistant to more than 90% of the races detected in western Canada, and all of them were resistant to the new races detected since 2000. Climatic conditions and cultivar resistance play an important role in the survival and propagation of these races on the Canadian prairies.

Using claims prediction model for road safety evaluation

Road safety analysis is typically undertaken using traffic collision data. However, the collision data often suffer from quality and reliability problems. These problems can inhibit the ability of road safety engineers to evaluate and analyze road safety performance. An alternate source of data that characterize the events of a traffic collision is the records that become available from an auto insurance claim. In settling an auto insurance claim, a claim adjuster must make an assessment and determination of the circumstances of the event, recording important contributing factors that led to the crash occurrence. As such, there is an opportunity to access and use the claims data in road safety engineering analysis. This paper presents the results of an initial attempt to use auto insurance claims records in road safety evaluation by developing and applying a claim prediction model. The prediction model will provide an estimate of the number of auto insurance claims that can be expected at signalized intersections in the Vancouver area of British Columbia, Canada. A discussion of the usefulness and application of the claim prediction model will be provided together with a recommendation on how the claims data could be utilized in the future.Key words: road safety improvement programs, auto insurance claims, road safety analysis, prediction models.

Spinal injuries in skiers and snowboarders.

Spinal injuries are among the most devastating injuries associated with recreational sports. Snowboarding spinal injury patterns have not been described. During two seasons (1994 to 1995 and 1995 to 1996), 34 skiers and 22 snowboarders suffered serious spinal injuries (fracture or neurologic deficit or both) at two ski areas in British Columbia, Canada. Ski patrol records, the Provincial Trauma Database, and hospital records were reviewed. Injury rates were based on computerized lift-ticket data and a population estimate of 15% snowboarders (ski patrol observation). The incidence of spinal injury among skiers was 0.01 per 1000 skier-days, and among snowboarders was 0.04 per 1000 snowboarder-days. Mean age was 34.5 years for skiers and 22.4 years for snowboarders. Seventy percent of the skiers were men, whereas all of the snowboarders were men. Jumping (intentional jump > 2 meters) was the cause of injury in 20% of skiers and 77% of snowboarders. Neither age nor sex accounted for any significant portion of this difference. The rate of spinal injuries among snowboarders is fourfold that among skiers. Although jumping is the primary cause of injury, it is an intrinsic element of snowboarding. Until research defines effective injury-prevention strategies, knowledge of the risk of snowboarding should be disseminated and techniques for safe jumping should be taught.

Multiattribute elicitation of wilderness preservation benefits: a constructive approach

This paper contributes to the development of a constructive approach to evaluating environmental resources, using a version of multiattribute value elicitation in a group setting. Section 1discusses the assumptions and practices of group multiattribute elicitation for public policy decisions. The good of interest is a potential doubling of designated wilderness areas in British Columbia. Two groups, totalling 28 subjects, participated in intensive half-day workshops in which they provided judgments regarding the amounts of tax revenues from forest industry activities each thought provincial residents should forego to achieve specified increases in wilderness preservation. Subjects were asked to consider direct and passive use values, spiritual values, and ecological service values. Subjects were also asked to consider separately the interests of the current generation and future generations of residents and to provide judgments regarding the marginal benefits of increasing preservation. An initial aggregated valuation question was followed by five more disaggregated questions. Subjects then compared and reconciled their value judgments for the aggregated and disaggregated questions. The results are generally comparable to those of a contingent valuation referendum-based survey for the same valuation issues.

Recent studies of residual tributyltin in coastal British Columbia sediments

Butyltin concentrations in the sediments of two coastal areas of British Columbia, Canada, are reported. Two recent box cores from the deepest basin in the Strait of Georgia were sectioned and analyzed by GC–atomic emission spectrometry. No butyltin compounds were detected above 0.5 μgSn kg−1 (dry weight) in either core. These results are compared to those for a previous (1991) core from the same area. In that study, tributyltin (TBT) concentrations were in the range 1–2 μgSn kg−1 down the core and were higher than those of either of the degradation products, dibutyltin (DBT) and monobutyltin (MBT). Radioisotope dating (210Po–210Pb counting methods) was used to establish the rates of sedimentation of 0.25 and 2.6 cm y−1 at the two sites. Data suggest that a combination of rapid deposition of new, less-contaminated material and degradation of previously deposited butyltin compounds has resulted in the observed absence. Thirty-three surface sediments from the northern BC coastal harbor at Prince Rupert, collected in 1995, were analyzed for butyltin residues by GC–FPD. Concentrations of TBT, DBT and MBT were in the ranges from below the appropriate limit of detection (LOD) to 1262, to 109 and to 37 μgSn kg−1, respectively. TBT/DBT ratios ranged from 0.2 to 62 with most above unity, indicating that there is continuing fresh input of TBT. The sources are almost exclusively large ocean-going vessels that use the harbor for long-term anchorage. These findings are discussed with reference to the global TBT status. © 1998 John Wiley & Sons, Ltd.

Height models for Red Alder (Alnus rubra Bong.) in British Columbia

Interest in managing red alder (Alnus rubra Bong.) for pulp, lumber and improving site quality is increasing. Proper management of this species requires growth and yield information. Height-age and years to breast height models developed for western Washington and northwestern Oregon are being used in British Columbia. It is unknown whether these models are suitable for British Columbia's conditions. Therefore, new models were developed from thirty stem analysis plots established in red alder stands in coastal areas of British Columbia. The sample trees in the plots were intensively sampled by taking sections out of the tree stems and counting the annual growth rings on each section. This led to height-age data for each tree, which was then averaged by age to get plot height-age data. Years to breast height and height-age models were developed from these data and are summarized in this paper. The height-age model was anamorphic, which contrasts with the model previously used in British Columbia. The new years to breast height model provides more resolution than the previous model.

Impact of Students with Special Needs on Teachers in Rural Communities

In order to develop relevant teacher education programs, teacher educators must understand attitudes, concerns and knowledge of inservice rural teachers toward inclusion of children with special needs in their classroom. Questionnaires were distributed to teachers in rural/remote areas of British Columbia. Results were indicative of the urgent need for providing additional human resources to assist with inclusionary practices, particularly the addition of trained assistants, parents, and community volunteers.

Organochlorine Pesticides and Polychlorinated Biphenyl Congeners in Ooligan Grease: A Traditional Food Fat of British Columbia First Nations

Levels of persistent organic pollutants including dichlorodiphenyltrichloroethane, hexachlorobenzene, hexachlorohexanes, dieldrin, chlordane, mirex, and polychlorinated biphenyls (PCB) were measured in ooligan fish (Thaleichthys pacificus) prepared in the way usually consumed and in ooligan grease collected from five communities (Nass River, Kitimaat, Bella Coola, Kingcome Inlet, and Knights Inlet) in the coastal area of British Columbia, Canada. Levels of chlorinated pesticides and PCB increased from the north to the south, with the lowest from Nass River and highest from Knights Inlet. Average levels of persistent organic pollutants (110 ng/g lipid of total chlorinated pesticide and 30 ng/g lipid of PCB) were lower than those reported in fish from the Great Lakes and similar to those from the Arctic and were below the regulation limits established by Health Canada. Therefore, consumption of ooligan grease presents minimal health risk from organochlorine exposure.

Population Ecology of Caribou in British Columbia

The abundance and geographic range of woodland caribou (Rangifer tarandus caribou) decreased in many areas of British Columbia during the 1900's. Recent studies have found that predation during the summer is the major cause of mortality and current population declines. Increased moose {Alecs alces) populations may be related to past and current caribou declines by sustaining greater numbers of wolves (Canis lupus). Mortality rates were greater in areas where caribou calved in forested habitats, in close proximity to predators and moose. Caribou populations which had calving sites in alpine areas, islands, and rugged mountains experienced lower mortality and were generally stable or increasing. A predator-induced population decline in one area appeared to stabilize at low caribou densities, suggesting that the wolf predation rate may be density dependent.

Hearing Impaired families: The social ecology of hearing loss

The services available to parents of children with hearing losses, and the options concerning the modes of communication and the educational programs for their children, have significant effects on family relations and the family's understanding of hearing impairment and deafness. This is particularly true in rural areas of British Columbia, Canada, where the range of programs is limited. This paper examines the programs available, parents' understandings of their options, the decisions they make, and the impact on the family of the selection and availability of programs.

Climate-based estimates of potential forage yields in Canada using a crop growth model

A crop growth model of the Food and Agricultural Organization of the United Nations (FAO) adapted for estimating yield potential of annual crops in Canada was modified to provide climate-based estimates of perennial forage yields (FORYLD). Subroutines were developed to estimate average cutting schedules and growth periods for legumes (alfalfa) and grasses (timothy, bromegrass, wheatgrass) from climatic normals data. Model estimates of cutting schedules and potential (constraint-free) yields without moisture stress ( B y) were in good agreement with observed values. A moisture stress factor (MSF) was used to estimate dry matter yields ( B ya) under rainfed conditions (i.e. B ya = MSF × B y). The MSF was determined from the soil moisture deficit-surplus ( D), which was based on available water content in the soil at the start of the growth period, rainfall and potential evapotranspiration over the growth period. In a test of individual cuts, using dependent data, a high percentage of cases (82%) had estimated values for B ya within 1 t ha −1 of observed values for alfalfa and timothy. In independent data tests of wheatgrasses, 95% and 58% of estimated cases were within 1.0 1 ha −1 and 0.5 t ha −1 of observed values, respectively. Average constraint-free yield ( B y) and dry matter yields under rainfed conditions ( B ya) were estimated for all soil map units on the Soils of Canada map, using FORYLD with 30-year averages of monthly climatic data. Estimates of B y for both alfalfa and grasses ranged from zero potential in northern areas to more than 18 t ha −1 in the most climatically favoured areas (southern Quebec, lower coastal areas in British Columbia, southern Alberta), based on a maximum of three cuts of alfalfa and two cuts of grasses. Estimated values of B ya for alfalfa in areas where B y was greater than zero ranged from less than 2 t ha −1 in the semi-arid regions of the prairies and parts of the interior of British Columbia, to more than 14 t ha −1 in the most climatically favourable areas of southern Ontario and Quebec and the lower coastal region of British Columbia. The results provide a reasonable basis for making comparisons of forage production capability between regions. Additional consideration of stand persistence and winter injury is needed if yield potential data are to be used for management decisions on forages.

Aesthetic concerns of children and parents in relation to different classifications of the Tooth Surface Index of Fluorosis.

Increasing prevalence of dental fluorosis for children both from fluoridated and non-fluoridated communities are now well documented. Along with recent studies purporting possible adverse health effects from fluorides, this proven public health intervention is again being challenged. This study was undertaken to determine the prevalence of dental fluorosis for children from fluoridated and non-fluoridated areas in British Columbia. In addition, children and parents were provided with an opportunity to express concerns about the aesthetics of the child's anterior teeth. Children from representative schools in two communities were surveyed using the Tooth Surface Index of Fluorosis (TSIF). Questionnaires were sent home to parents to detail their child's use of various fluoride preventive practices and residence histories. Completed questionnaires were returned and exams were performed on 1131 children. Of those examined, 60% had dental fluorosis on at least two tooth surfaces, only 8% had scores ranging from "2" to "6", and 52% were classified with a score of "1". Parental and child ratings on the aesthetics or color of the child's teeth suggests that there are few children with aesthetic problems in the TSIF category of "1". While concerns of parents were more common, the actual source of those concerns was not assessed in the questionnaire. Not unexpectedly, children with fluorosis on anterior teeth ranging between TSIF scores of "2" to "6" appear to have increased concerns about tooth color. Data from children with confirmed residence histories from fluoridated communities suggest that the occurrence of aesthetic problems in these children is rare.

A study of the contributions of various gravimetric data types on the estimation of gravity field parameters in the mountains

In this paper, new rigorous, simpler, and more efficient formulas are used to estimate the effect of the terrain on geoid undulations and deflections of the vertical. The new formulas are based on the successive application in the spectral domain of Molodensky's vertical derivative operator to powers of heights. A number of numerical tests are carried out in the area of British Columbia (BC) in western Canada. Geoid undulations and deflections of the vertical are computed by combining a geopotential model complete to degree and order 360, mean 5 arc min × 5 arc min free air gravity anomalies and height data on a 1 km × 1 km grid. In geoid undulation computations, the indirect effect of Helmert's second condensation reduction is taken into account. To assess the quality of the predicted deflections of the vertical and geoid undulations, the computed quantities are compared to a set of astronomic deflections of the vertical and geoid undulations derived from a combination of Global Positioning System with leveled orthometric heights. Test results present a precision of about ±2.0 arc sec for deflections, thus fulfilling the requirements for the reduction of geodetic measurements in any case. The achievable precision for geoid undulation differences, close to ±0.50 m, is also acceptable to determine an accurate relative geoid in the test area useful for various geodetic applications.

Lung function and chest radiograph abnormalities among construction insulators

We carried out a prevalence survey of pulmonary health parameters among current and retired construction insulators (50 years old and older) from all areas of British Columbia, Canada. The study population included 59 active workers (81 percent participation in this group) and 29 workers who were retired or inactive due to illness (69% participation). Radiograph results were compared to those from actively working bus mechanics from the same age group, and retired grain and civic workers, who were all tested in the same manner. Chest radiographs were read independently by two readers and were graded according to the ILO classification system. Pleural abnormalities alone were found in 34% (20) of active workers (5% in comparison group) and 45% (13) of non-active workers (14% in comparison group). Rates for parenchymal abnormalities for these same groups (ILO grade 1/0 or higher) were 17% (5%) and 20% (5%), respectively. Airflow obstruction was present in 35% (31) of the insulators and was associated with age and the presence of diffuse pleural thickening, and 5 or more years of employment in pulp mills. Restrictive lung function was present in 22% (19) of the insulator population and was associated with age and radiographic evidence of parenchymal fibrosis. The results indicate that construction insulators, a group at high risk for asbestos-related lung disease, also have a high prevalence of airflow obstruction. This was associated not only with smoking, but also with diffuse pleural thickening and a history of pulp-mill employment, suggesting that airflow obstruction in this population is also partly work related.

Stomach Contents of Dunlins Collected in Western Washington

The dunlin (Calidris alpina) is the most common sandpiper (Family Scolopacidae) that winters on the Pacific coast of North America (Bent 1927; Jewett et al. 1953; and Christmas Bird Count data published in American Birds during the last two decades). The food eaten by dunlins has been described from many locations throughout their distribution (see review in Cramp and Simmons 1983). In North America, food eaten by dunlins has been described from the Arctic (Holmes 1966; Baker 1977), at migratory stop-overs in the midwest (Brooks 1962) and British Columbia (Munro 1936), and at wintering areas in British Columbia (Fry 1980) and California (Recher 1964; Holmes 1966; Holmberg 1971). In addition, the food eaten by dunlins has been described from populations wintering in Grays Harbor (Smith and Mudd 1976; Kalinowski et al. 1982) and the San Juan Islands (Couch 1966) in Washington state. In this note, we describe the amounts and kinds of food eaten by dunlins at four estuaries in western Washington state; three in Puget Sound (Kennedy Creek delta, Nisqually River delta and Samish Bay) and one in Grays Harbor on the coast (Bowerman Basin). A description of these areas is provided by Brennan et al. (1985). We have previously summarized the food eaten by dunlins in western Washington in relation to the availability of prey and patterns of over-winter weight changes in dunlins (Buchanan et al. 1985). Our purpose here is to provide a complete listing of all food items obtained from our collections of dunlins.