Mapping the Core: Chlamydia and Gonorrhea Infections in Calgary, Alberta

Brown

et al. 2011

Annals of Epidemiology

Sexually transmitted infections (STIs) tend to cluster in geographically definable core areas, or risk spaces.(1-15) These core areas are often located in low socioeconomic status (SES) urban neighborhoods, (4,7,9,16,17) suggesting that socio-cultural determinants of health may influence the clustered spatial pattern observed for STIs.Several socio-cultural risk factors have been associated with gonorrhea in urban environments including individual level factors such as SES and community level (e.g. county or state) factors such as prevalence of infection,(18) % urbanicity,(19) neighborhood instability,(20) gender imbalance with more women than men, low social capital, (21,22) and high % Black or Hispanic.(5,23) For instance, low SES can impair timely access to STI services, thereby increasing the duration of infection and ultimately the prevalence of infection within a sexual network. Prevalence of an STI has a direct impact on the incidence of infection. As STI prevalence increases, the likelihood of finding a sexual partner that has an STI also increases. The power to negotiate the terms and conditions around sex is affected by both an imbalanced sex ratio, and the proportion of single parents in a Corresponding Author: Dionne Gesink, University of Toronto, Dalla Lana School of Public Health, 155 College St, 6 th Floor, Toronto, Ontario, M5T 3M7, Canada, dionne.gesink@utoronto.ca,. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Rurality may influence STI transmission through the low density and availability of partners within a sexual network, as well as the culture and social norms around sex and relationships within a community. Rurality may also act as a proxy for low physician density, poor access to STI health services, or community racial/ethnic homogeneity and hence, partner STI prevalence. NIH Public AccessRace/ethnicity itself is not causally associated with STIs,(27) however, it can provide strong predictive power of STI risk.(28-33) For instance, in North Carolina, racial/ethnic differences in gonorrhea rates have persisted over time (18,29) suggesting that race/ethnicity is a proxy for other STI risk factors. Possible explanatory factors include partner STI prevalence, assortative mixing, historic segregation, racism, unequal access to healthcare, or high incarceration rates. (18,29,32,34) Our primary objective was to determine if the spatial pattern of gonorrhea observed for North Carolina (NC) was influenced by neighbourhood-level socio-cultural determinants of health ( Figure 1). A secondary objective was to investigate the influence of race/ethnicity o...

Section: Discussionsupporting

confidence: 66%

Are Neighborhood Sociocultural Factors Influencing the Spatial Pattern of Gonorrhea in North Carolina?

Sullivan

Brown

et al. 2011

Annals of Epidemiology

“…The concept of core areas has only been evaluated in large urban areas (3, 5, 6, 8, 9, 12, 17, 22). In contrast to other high incidence areas in the United States (US), STIs in the southeast are not concentrated in urban areas only.…”

Section: Introductionmentioning

confidence: 99%

Does Core Area Theory Apply to Sexually Transmitted Diseases in Rural Environments?

Sexually Transmitted Diseases

Sullivan

Norwood

et al. 2013

Background Our objective was to determine the extent to which geographical core areas for gonorrhea and syphilis are located in rural areas, as compared to urban areas. Methods Incident gonorrhea (January 1, 2005 to December 31, 2010) and syphilis (January 1, 1999 to December 31, 2010) rates were estimated and mapped by census tract and quarter. Rurality was measured using percent rural and rural-urban commuting area (RUCA; rural, small town, micropolitan, or urban). SaTScan was used to identify spatiotemporal clusters of significantly elevated rates of infection. Clusters lasting five years or longer were considered core areas; clusters of shorter duration were considered outbreaks. Clusters were overlaid on maps of rurality and qualitatively assessed for correlation. Results Twenty gonorrhea core areas were identified; 65% in urban centers, 25% in micropolitan areas, and the remaining 10% were geographically large capturing combinations of urban, micropolitan, small town and rural environments. Ten syphilis core areas were identified with 80% in urban centers and 20% capturing two or more RUCAs. All ten of the syphilis core areas (100%) overlapped with gonorrhea core areas. Conclusions Gonorrhea and syphilis rates were high for rural parts of North Carolina; however, no core areas were identified exclusively for small towns or rural areas. The main pathway of rural STI transmission may be through the interconnectedness of urban, micropolitan, small town and rural areas. Directly addressing STIs in urban and micropolitan communities may also indirectly help address STI rates in rural and small town communities.

“…However, core areas indicate meeting places for high risk behaviours like IDU, which may include some places frequented by these hard to reach populations . Following similar methodology from previous research, we used a cut‐off of top 20% of quintile of annualized HCV diagnoses rate in DA's to compare rates over time. However, this percentage may differ in different settings depending on disease prevalence or incidence.…”

Section: Discussionmentioning

confidence: 99%

“…Following similar methodology from previous research,44 we used a cut-off of top 20% of quintile of annualized HCV diagnoses rate in DA's to compare rates over time. However, this percentage may differ in different settings depending on disease prevalence or incidence.…”

mentioning

confidence: 99%

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

Butt

Mak

Journal of Viral Hepatitis

et al. 2018

Summary “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.