Visible minority status and occupation were associated with increased COVID-19 infection in Greater Vancouver British Columbia between June and November 2020: an ecological study.

Background: The COVID-19 pandemic has highlighted health disparities, especially among specific population groups. This study examines the spatial relationship between the proportion of visible minorities (VM), occupation types and COVID-19 infection in the Greater Vancouver region of British Columbia, Canada. Methods: Provincial COVID-19 case data between June 24, 2020, and November 7, 2020, were aggregated by census dissemination area and linked with sociodemographic data from the Canadian 2016 census. Bayesian spatial Poisson regression models were used to examine the association between proportion of visible minorities, occupation types and COVID-19 infection. Models were adjusted for COVID-19 testing rates and other sociodemographic factors. Relative risk (RR) and 95% Credible Intervals (95% CrI) were calculated. Results: We found an inverse relationship between the proportion of the Chinese population and risk of COVID-19 infection (RR = 0.98 95% CrI = 0.96, 0.99), whereas an increased risk was observed for the proportions of the South Asian group (RR = 1.10, 95% CrI = 1.08, 1.12), and Other Visible Minority group (RR = 1.06, 95% CrI = 1.04, 1.08). Similarly, a higher proportion of frontline workers (RR = 1.05, 95% CrI = 1.04, 1.07) was associated with higher infection risk compared to non-frontline. Conclusion: Despite adjustments for testing, housing, occupation, and other social economic status variables, there is still a substantial association between the proportion of visible minorities, occupation types, and the risk of acquiring COVID-19 infection in British Columbia. This ecological analysis highlights the existing disparities in the burden of diseases among different visible minority populations and occupation types.

Understanding the impact of mobility on COVID-19 spread: A hybrid gravity-metapopulation model of COVID-19.

The outbreak of the severe acute respiratory syndrome coronavirus 2 started in Wuhan, China, towards the end of 2019 and spread worldwide. The rapid spread of the disease can be attributed to many factors including its high infectiousness and the high rate of human mobility around the world. Although travel/movement restrictions and other non-pharmaceutical interventions aimed at controlling the disease spread were put in place during the early stages of the pandemic, these interventions did not stop COVID-19 spread. To better understand the impact of human mobility on the spread of COVID-19 between regions, we propose a hybrid gravity-metapopulation model of COVID-19. Our modeling framework has the flexibility of determining mobility between regions based on the distances between the regions or using data from mobile devices. In addition, our model explicitly incorporates time-dependent human mobility into the disease transmission rate, and has the potential to incorporate other factors that affect disease transmission such as facemasks, physical distancing, contact rates, etc. An important feature of this modeling framework is its ability to independently assess the contribution of each factor to disease transmission. Using a Bayesian hierarchical modeling framework, we calibrate our model to the weekly reported cases of COVID-19 in thirteen local health areas in Metro Vancouver, British Columbia (BC), Canada, from July 2020 to January 2021. We consider two main scenarios in our model calibration: using a fixed distance matrix and time-dependent weekly mobility matrices. We found that the distance matrix provides a better fit to the data, whilst the mobility matrices have the ability to explain the variance in transmission between regions. This result shows that the mobility data provides more information in terms of disease transmission than the distances between the regions.

Travel Time to Delivery, Antenatal Care, and Birth Outcomes: A Population-Based Cohort of Uncomplicated Pregnancies in British Columbia, 2012-2019.

OBJECTIVE: Health policy and system leaders need to know whether long travel time to a delivery facility adversely affects birth outcomes. In this study, we estimated associations between travel time to delivery and outcomes in low-risk pregnancies. METHODS: This population-based cohort included all singleton births without obstetric comorbidities or intrapartum facility transfers in British Columbia, Canada, from 2012 to 2019. Travel time was measured from maternal residential postal code to delivery facility using road network analysis. We estimated associations between travel time and severe maternal morbidity, stillbirth, pre-term birth, and small-for-gestational age (SGA) and large-for-gestational age (LGA) status using logistic regression, adjusted for confounders (adjusted odds ratios [aORs]). To examine variations in associations between travel time and outcomes by antenatal care utilization, we stratified models by antenatal care categories. RESULTS: Of 232 698 births, 3.8% occurred at a facility ≥60 minutes from the maternal residence. Obesity, adolescent age, substance use, inadequate prenatal care, and low socioeconomic status were more frequent among those traveling farther for delivery. Travel time ≥120 minutes was associated with increased risk of stillbirth (aOR 1.8; 95% CI 1.2-2.8), pre-term birth (aOR 2.3; 95% CI 2.1-2.5), LGA (aOR 1.5; 95% CI 1.4-1.6), and severe maternal morbidity (aOR 1.5; 95% CI 1.2-1.8), but not SGA (aOR 1.0; 95% CI 0.8-1.1), when compared with a travel time of 1-29 minutes. Risk of stillbirth was greatest with inadequate and intensive (adequate plus) antenatal care but persisted for severe maternal morbidity, pre-term birth, and LGA across categories. CONCLUSION: Longer travel time to delivery was associated with increased risk of adverse outcomes in low-risk pregnancies after adjusting for confounding factors. Associations were stronger among those with inadequate antenatal care.

Passive Tick Surveillance and Detection of Borrelia Species in Ticks from British Columbia, Canada: 2002-2018.

Lyme disease, caused by Borrelia burgdorferi sensu lato (s.l.) complex, is the most common vector-borne disease in North America. This disease has a much lower incidence in western compared with eastern North America. Passive tick surveillance data submitted over 17 years from 2002 to 2018 were analyzed to determine the occurrence of tick species and the prevalence of Borrelia spp. in ticks in British Columbia (BC), Canada. The BC Centre for Disease Control Public Health Laboratory received tick submissions from physicians, veterinarians, and BC residents. Ticks were identified to species, and all ticks, except Dermacentor andersoni, were tested using generic B. burgdorferi s.l. primer sets and species-specific PCR primer sets for B. burgdorferi sensu stricto (s.s.). Tick submission data were analyzed to assess temporal and geographical trends, tick life stages, and tick species. Poisson regression was used to assess temporal trends in annual tick submissions. A total of 15,464 ticks were submitted. Among these, 0.29% (n = 10,235) of Ixodes spp. ticks and 5.3% (n = 434) of Rhipicephalus sanguineus ticks were found carrying B. burgdorferi s.s. B. burgdorferi s.s. was primarily detected in Ixodes pacificus (52%; n = 16) and Ixodes angustus ticks (19%; n = 6) retrieved from humans (n = 5) and animals (n = 26). B. burgdorferi was found in ticks submitted throughout the year. Ixodes spp. ticks were primarily submitted from the coastal regions of southwestern BC, and D. andersoni ticks were primarily submitted from southern interior BC. The number of human tick submissions increased significantly (p < 0.001) between 2013 and 2018. The annual prevalence of B. burgdorferi in ticks remained stable during the study period. These findings correspond to those observed in US Pacific Northwestern states. Passive tick surveillance is an efficient tool to monitor long-term trends in tick distribution and B. burgdorferi prevalence in a low endemicity region.

Associations of five food- and water-borne diseases with ecological zone, land use and aquifer type in a changing climate.

BACKGROUND: Food- and water-borne pathogens exhibit spatial heterogeneity, but attribution to specific environmental processes is lacking while anthropogenic climate change alters these processes. The goal of this study was to investigate ecology, land-use and health associations of these pathogens and to make future disease projections. METHODS: The rates of five acute gastrointestinal illnesses (AGIs) (campylobacteriosis, Verotoxin- producing Escherichia coli, salmonellosis, giardiasis and cryptosporidiosis) from 2000 to 2013 in British Columbia, Canada, were calculated across three environmental variables: ecological zone, land use, and aquifer type. A correlation analysis investigated relationships between 19 climatic factors and AGI. Mean annual temperature at the ecological zone scale was used in a univariate regression model to calculate annual relative AGI risk per 1 °C increase. Future cases attributable to climate change were estimated into the 2080s. FINDINGS: Each of the bacterial AGI rates was correlated with several annual temperature-related factors while the protozoan AGIs were not. In the regression model, combined relative risk for the three bacterial AGIs was 1.1 [95% CI: 1.02-1.21] for every 1 °C in mean annual temperature. Campylobacteriosis, salmonellosis and giardiasis rates were significantly higher (p < 0.05) in the urban land use class than in the rural one. In rural areas, bacteria and protozoan AGIs had significantly higher rates in the unconsolidated aquifers. Verotoxin-producing Escherichia coli rates were significantly higher in watersheds with more agricultural land, while rates of campylobacteriosis, salmonellosis and giardiasis were significantly lower in agricultural watersheds. Ecological zones with higher bacterial AGI rates were generally projected to expand in range by the 2080s. INTERPRETATION: These findings suggest that risk of AGI can vary across ecosystem, land use and aquifer type, and that warming temperatures may be associated with an increased risk of food-borne AGI. In addition, spatial patterns of these diseases are projected to shift under climate change.

Spatial-Temporal Epidemiology of the Syphilis Epidemic in Relation to Neighborhood-Level Structural Factors in British Columbia, 2005-2016.

BACKGROUND: Spatial clusters of syphilis have been observed within several jurisdictions globally; however, the degree to which they are predicted by the spatial distributions of gay, bisexual, and other men who have sex with men (GBM) and testing remains unknown. We sought to describe the spatial-temporal epidemiology of infectious syphilis and identify associations between neighborhood-level factors and rates of syphilis, in British Columbia, Canada. METHODS: We used ArcGIS to map infectious syphilis cases among men (2005 to 2016), SaTScan to detect areas with significantly elevated rates of syphilis, and spatial regression to identify associations between neighborhood-level factors and rates of syphilis. RESULTS: Five clusters were identified: a core in downtown Vancouver (incidence rate ratio [IRR], 18.0; 2007-2016), 2 clusters adjacent to the core (IRR, 3.3; 2012-2016; and IRR, 2.2; 2013-2016), 1 cluster east of Vancouver (IRR, 2.1; 2013-2016), and 1 cluster in Victoria (IRR, 4.3; 2015-2016). Epidemic curves were synchronized across cluster and noncluster regions. Neighborhood-level GBM population estimates and testing rates were both associated with syphilis rates; however, the spatial distribution of syphilis was not fully explained by either of these factors. CONCLUSIONS: We identified two novel ecologic correlates of the spatial distribution of infectious syphilis-density of GBM and rates of syphilis testing-and found that these factors partially, though not entirely, explained the spatial distribution of clusters. Residual spatial autocorrelation suggests that greater syphilis testing coverage may be needed and low-barrier GBM-affirming testing should be expanded to regions outside the core.

Applying core theory and spatial analysis to identify hepatitis C virus infection "core areas" in British Columbia, Canada.

"Core areas" of transmission for bacterial sexually transmitted infections have been identified. However, it is unclear whether core areas apply to viral infections, such as hepatitis C virus (HCV). We used geographic mapping and spatial analysis to identify distinct core areas of HCV infection in British Columbia (BC) using the BC Hepatitis Testers Cohort (BC-HTC), 1990-2013. The BC-HTC includes all BC residents tested for HCV (~1.5 million; 1990-2013). Core HCV infection areas were identified spatially and temporally for five time periods (1990-1993, 1994-1998, 1999-2003, 2004-2008 and 2009-2013) through thematic mapping, Kernel Density Estimation, Hotspot analysis and cluster analysis at the Census dissemination area level in ArcGIS and SatScan. HCV infection core areas were consistently identified. HCV core areas expanded from the downtown of major cities in different regions of BC (Metro Vancouver, Vancouver Island, and Northern BC; 1990-1998), to smaller cities in Metro Vancouver and Interior BC (2000 onwards). Statistically significant clusters, or hotspots, were also observed for downtown Vancouver, Northern BC (Prince George) and Vancouver Island from 1990 to 2008 with expansion to other urban areas in Metro Vancouver from 1990-2013. Statistically significant clusters persisted after adjustment for injection drug use, number of HCV tests, age, sex, material and social deprivation. Persistence of areas with high HCV diagnoses rates in Vancouver and Prince George supports the theory of core areas of HCV transmission. Identification of core areas can inform prevention, care and treatment programme interventions and evaluate their impact over time.

Projected local rain events due to climate change and the impacts on waterborne diseases in Vancouver, British Columbia, Canada.

BACKGROUND: Climate change is increasing the number and intensity of extreme weather events in many parts of the world. Precipitation extremes have been linked to both outbreaks and sporadic cases of waterborne illness. We have previously shown a link between heavy rain and turbidity to population-level risk of sporadic cryptosporidiosis and giardiasis in a major Canadian urban population. The risk increased with 30 or more dry days in the 60 days preceding the week of extreme rain. The goal of this study was to investigate the change in cryptosporidiosis and giardiasis risk due to climate change, primarily change in extreme precipitation. METHODS: Cases of cryptosporidiosis and giardiasis were extracted from a reportable disease system (1997-2009). We used distributed lag non-linear Poisson regression models and projections of the exposure-outcome relationship to estimate future illness (2020-2099). The climate projections are derived from twelve statistically downscaled regional climate models. Relative Concentration Pathway 8.5 was used to project precipitation derived from daily gridded weather observation data (~ 6 × 10 km resolution) covering the central of three adjacent watersheds serving metropolitan Vancouver for the 2020s, 2040s, 2060s and 2080s. RESULTS: Precipitation is predicted to steadily increase in these watersheds during the wet season (Oct. -Mar.) and decrease in other parts of the year up through the 2080s. More weeks with extreme rain (>90th percentile) are expected. These weeks are predicted to increase the annual rates of cryptosporidiosis and giardiasis by approximately 16% by the 2080s corresponding to an increase of 55-136 additional cases per year depending upon the climate model used. The predicted increase in the number of waterborne illness cases are during the wet months. The range in future projections compared to historical monthly case counts typically differed by 10-20% across climate models but the direction of change was consistent for all models. DISCUSSION: If new water filtration measures had not been implemented in our study area in 2010-2015, the risk of cryptosporidiosis and giardiasis would have been expected to increase with climate change, particularly precipitation changes. In addition to the predicted increase in the frequency and intensity of extreme precipitation events, the frequency and length of wet and dry spells could also affect the risk of waterborne diseases as we observed in the historical period. These findings add to the growing evidence regarding the need to prepare water systems to manage and become resilient to climate change-related health risks.

Searching for clues for eighteen years: Deciphering the ecological determinants of Cryptococcus gattii on Vancouver Island, British Columbia.

Cryptococcus gattii emerged on Vancouver Island in 1999 for unknown reasons, causing human and animal fatalities and illness. The apparent emergence of this fungus in another temperate area, this time in the Pacific Northwest, suggests the fungus may have expanded its ecological niche. Yet studies that directly examine the potential roles of climatic and land use changes on C. gattii are still lacking. We aim to summarize the existing global literature on the ecology of C. gattii, with particular focus on the gap in knowledge surrounding the potential effects of climatic and land use changes. We systematically reviewed English peer-reviewed literature on the ecological determinants of C. gattii. We included studies published from January 1970 through June 2016 and identified 56 relevant studies for our review. We identified environmental isolations of C. gattii from 18 countries, spanning 72 separate regions across six continents. Fifty-three tree species were associated with C. gattii, spanning 10 climate classifications and 36 terrestrial ecoregions. No studies directly tested the potential effects of climatic changes (including climatic oscillations and global climate change) on C. gattii, while only one study directly assessed those of land use change. To improve model predictions of current and future distributions of C. gattii, more focus is needed on the potential effects of climatic and land use changes to help decrease the public health risk. The apparent emergence of C. gattii in British Columbia is also an opportunity to explore the factors behind emerging infectious diseases in Canada and elsewhere.

Associations between extreme precipitation and acute gastro-intestinal illness due to cryptosporidiosis and giardiasis in an urban Canadian drinking water system (1997-2009).

Drinking water related infections are expected to increase in the future due to climate change. Understanding the current links between these infections and environmental factors is vital to understand and reduce the future burden of illness. We investigated the relationship between weekly reported cryptosporidiosis and giardiasis (n = 7,422), extreme precipitation (>90th percentile), drinking water turbidity, and preceding dry periods in a drinking water system located in greater Vancouver, British Columbia, Canada (1997-2009) using distributed lag non-linear Poisson regression models adjusted for seasonality, secular trend, and the effect of holidays on reporting. We found a significant increase in cryptosporidiosis and giardiasis 4-6 weeks after extreme precipitation. The effect was greater following a dry period. Similarly, extreme precipitation led to significantly increased turbidity only after prolonged dry periods. Our results suggest that the risk of cryptosporidiosis and giardiasis increases with extreme precipitation, and that the effects are more pronounced after a prolonged dry period. Given that extreme precipitation events are expected to increase with climate change, it is important to further understand the risks from these events, develop planning tools, and build resilience to these future risks.

Identification of spatial and cohort clustering of tuberculosis using surveillance data from British Columbia, Canada, 1990-2013.

Since 2000, the global incidence of tuberculosis (TB) has decreased by 1.5% per year, becoming increasingly clustered in key subpopulations in low incidence settings. TB clustering can manifest spatially from recent transmission, or in non-spatial cohort clusters resulting from reactivation of latent infection in populations with shared risk factors. Identifying and interrupting disease clusters is required to eliminate TB in low incidence countries. Here we demonstrate an analytical approach for detecting both spatial and cohort clustering of TB among population subgroups, and describe the value in differentiating these forms of clustering. TB cases in British Columbia meeting the Canadian case definition were geocoded and mapped using Geographic Information Systems (GIS). Incidence rates were calculated for three periods (1990-1997, n = 2556; 1998-2005, n = 2488; 2006-2013, n = 2225) among Canadian born (CB) and foreign-born (FB) populations using denominator data from the Canadian Census. Spatial clusters were identified using a scanning window statistic (SaTScan) and overlaid on provincial incidence maps. Country of birth (cohort) clustering in the FB was identified using Lorenz curves and Gini coefficients. TB incidence in the CB population was generally low, but punctuated with few areas of high incidence; the spatial clusters identified in the CB match previously identified clusters. TB incidence in the FB did not show spatially localized clusters. However, Lorenz curves revealed substantial, and increasing, cohort clustering in the FB in semi-urban and rural regions of British Columbia, and less pronounced, and decreasing, clustering in urban regions. In general, the TB incidence in groups defined by country of birth shifted over time to become increasingly uniform across regions. Our approach, based on spatial analysis and the application of Lorenz curves revealed a complex coexistence of spatial and cohort clustering. Spatial and cohort clusters require differing public health responses, and differentiating types of clustering can inform TB prevention programs.

Climatic Influences on Cryptococcus gattii [corrected] Populations, Vancouver Island, Canada, 2002-2004.

Vancouver Island, Canada, reports the world's highest incidence of Cryptococcus gattii infection among humans and animals. To identify key biophysical factors modulating environmental concentrations, we evaluated monthly concentrations of C. gatti in air, soil, and trees over a 3-year period. The 2 study datasets were repeatedly measured plots and newly sampled plots. We used hierarchical generalized linear and mixed effect models to determine associations. Climate systematically influenced C. gattii concentrations in all environmental media tested; in soil and on trees, concentrations decreased when temperatures were warmer. Wind may be a key process that transferred C. gattii from soil into air and onto trees. C. gattii results for tree and air samples were more likely to be positive during periods of higher solar radiation. These results improve the understanding of the places and periods with the greatest C. gattii colonization. Refined risk projections may help susceptible persons avoid activities that disturb the topsoil during relatively cool summer days.

Surveillance for Borrelia burgdorferi in Ixodes Ticks and Small Rodents in British Columbia.

To determine the prevalence of Borrelia burgdorferi in British Columbian ticks, fieldwork was conducted over a 2-year period. In all, 893 ticks (Ixodes pacificus, I. angustus, I. soricis, Ixodes spp., and Dermacentor andersoni) of different life stages were retrieved from 483 small rodents (Peromyscus maniculatus, Perognathus parvus, and Reithrodontomys megalotis). B. burgdorferi DNA was detected in 5 out of 359 tick pools, and 41 out of 483 mice were serologically confirmed to have antibodies against B. burgdorferi. These results were consistent with previous studies, data from passive surveillance in British Columbia, and data from neighboring states in the Pacific Northwest, suggesting a continually low prevalence of B. burgdorferi in British Columbia ticks.

The Fungus among Us: Cryptococcus neoformans and Cryptococcus gattii Ecological Modeling for Colombia.

The environmental isolation of Cryptococcus spp. is typically a difficult undertaking. Collecting samples in the field is costly in terms of travel, personnel time and materials. Furthermore, the recovery rate of Cryptococcus spp. may be very low, thereby requiring a large number of samples to be taken without any guarantee of success. Ecological niche modeling is a tool that has traditionally been used to forecast the distribution of plant and animal of species for biodiversity and conservation purposes. Here, we use it in a public health application to produce risk area maps for cryptococcal disease in Colombia. The Genetic Algorithm for Ruleset Production (GARP) was used to create models for Cryptococcus neoformans (C. neoformans) and Cryptococcus gattii (C. gattii), based on environmental sampling and clinical records data recorded since 1987. These maps could be used to focus public health messaging related to cryptococcal disease, and it enables us to characterize the ecological niche for Cryptococcus in Colombia. We found that the OPEN ACCESS J. Fungi 2015, 1 333 ecological niche for C. gattii in Colombia is quite diverse, establishing itself in sub-tropical and temperate ecoregions within the country. This suggests that C. gattii is highly adaptive to different ecological conditions in Colombia and different regions of the world.

Carriage of Clostridium difficile by wild urban Norway rats (Rattus norvegicus) and black rats (Rattus rattus).

Clostridium difficile is an important cause of enteric infections in humans. Recently, concerns have been raised regarding whether animals could be a source of C. difficile spores. Although colonization has been identified in a number of domestic species, the ability of commensal pests to serve as a reservoir for C. difficile has not been well investigated. The objective of this study was to determine whether urban rats (Rattus spp.) from Vancouver, Canada, carry C. difficile. Clostridium difficile was isolated from the colon contents of trapped rats and was characterized using ribotyping, toxinotyping, and toxin gene identification. Generalized linear mixed models and spatial analysis were used to characterize the ecology of C. difficile in rats. Clostridium difficile was isolated from 95 of 724 (13.1%) rats, although prevalence differed from 0% to 46.7% among city blocks. The odds of being C. difficile positive decreased with increasing weight (odds ratio [OR], 0.67; 95% confidence interval [CI], 0.53 to 0.87), suggesting that carriage is more common in younger animals. The strains isolated included 9 ribotypes that matched recognized international designations, 5 identified by our laboratory in previous studies, and 21 "novel" ribotypes. Some strains were clustered geographically; however, the majority were dispersed throughout the study area, supporting environmental sources of exposure and widespread environmental contamination with a variety of C. difficile strains. Given that urban rats are the source of a number of other pathogens responsible for human morbidity and mortality, the potential for rats to be a source of C. difficile for humans deserves further consideration.

Ecology of Leptospira interrogans in Norway rats (Rattus norvegicus) in an inner-city neighborhood of Vancouver, Canada.

BACKGROUND: Leptospira interrogans is a bacterial zoonosis with a worldwide distribution for which rats (Rattus spp.) are the primary reservoir in urban settings. In order to assess, monitor, and mitigate the risk to humans, it is important to understand the ecology of this pathogen in rats. The objective of this study was to characterize the ecology of L. interrogans in Norway rats (Rattus norvegicus) in an impoverished inner-city neighborhood of Vancouver, Canada. METHODOLOGY/PRINCIPAL FINDINGS: Trapping was performed in 43 city blocks, and one location within the adjacent port, over a 12 month period. Kidney samples were tested for the presence of L. interrogans using PCR and sequencing. A multivariable model was built to predict L. interrogans infection status in individual rats using season and morphometric data (e.g., weight, sex, maturity, condition, etc.) as independent variables. Spatial analysis was undertaken to identify clusters of high and low L. interrogans prevalence. The prevalence of L. interrogans varied remarkably among blocks (0-66.7%), and spatial clusters of both high and low L. interrogans prevalence were identified. In the final cluster-controlled model, characteristics associated with L. interrogans-infection in rats included weight (OR = 1.14, 95% CI = 1.07-1.20), increased internal fat (OR = 2.12, 95% CI = 1.06-4.25), and number of bite wounds (OR = 1.20, 95% CI = 0.96-1.49). CONCLUSIONS/SIGNIFICANCE: Because L. interrogans prevalence varied with weight, body fat, and bite wounds, this study suggests that social structure and interactions among rats may influence transmission. The prevalence and distribution of L. interrogans in rats was also highly variable even over a short geographic distance. These factors should be considered in future risk management efforts.

A decade of experience: Cryptococcus gattii in British Columbia.

It has been over a decade since Cryptococcus gattii was first recognized as the causative organism of an outbreak of cryptococcosis on Vancouver Island, British Columbia. A number of novel observations have been associated with the study of this emergent pathogen. A novel genotype of C. gattii, VGIIa was described as the major genotype associated with clinical disease. Minor genotypes, VGIIb and VGI, are also responsible for disease in British Columbians, in both human and animal populations. The clinical major genotype VGIIa and minor genotype VGIIb are identical to C. gattii isolated from the environment of Vancouver Island. There is more heterogeneity in VGI, and a clear association with the environment is not apparent. Between 1999 and 2010, there have been 281 cases of C. gattii cryptococcosis. Risk factors for infection are reported to be age greater than 50 years, history of smoking, corticosteroid use, HIV infection, and history of cancer or chronic lung disease. The major C. gattii genotype VGIIa is as virulent in mice as the model Cryptococcus, H99 C. neoformans, although the outbreak strain produces a less protective inflammatory response in C57BL/6 mice. The minor genotype VGIIb is significantly less virulent in mouse models. Cryptococcus gattii is found associated with native trees and soil on Vancouver Island. Transiently positive isolations have been made from air and water. An ecological niche for this organism is associated within a limited biogeoclimatic zone characterized by daily average winter temperatures above freezing.

How big is the Lyme problem? Using novel methods to estimate the true number of Lyme disease cases in British Columbia residents from 1997 to 2008.

Lyme disease (LD) is rare in British Columbia (BC) and, despite being a reportable condition since 1994, may be underreported. Here we review all provincial laboratory and clinical databases to determine the number of LD cases reported in BC from 1997 to 2008. We analyzed demographic characteristics of LD cases and used capture-recapture methodology to estimate the true number of cases in BC for this period. From 1997 to 2008, 93 confirmed cases of LD were reported in BC. Conservative capture-recapture estimates place the true number of LD cases in BC during this period at 142 (95% confidence interval: 111-224), indicating up to 40% underreporting of this rare disease. Despite this underreporting, BC continues to have low endemic risk of LD. Strategies are needed to increase both physician awareness and the use of preventive measures in the BC population, including for those traveling to other endemic areas.

West Nile virus range expansion into British Columbia.

In 2009, an expansion of West Nile virus (WNV) into the Canadian province of British Columbia was detected. Two locally acquired cases of infection in humans and 3 cases of infection in horses were detected by ELISA and plaque-reduction neutralization tests. Ten positive mosquito pools were detected by reverse transcription PCR. Most WNV activity in British Columbia in 2009 occurred in the hot and dry southern Okanagan Valley. Virus establishment and amplification in this region was likely facilitated by above average nightly temperatures and a rapid accumulation of degree-days in late summer. Estimated exposure dates for humans and initial detection of WNV-positive mosquitoes occurred concurrently with a late summer increase in Culex tarsalis mosquitoes (which spread western equine encephalitis) in the southern Okanagan Valley. The conditions present during this range expansion suggest that temperature and Cx. tarsalis mosquito abundance may be limiting factors for WNV transmission in this portion of the Pacific Northwest.