The Sociospatial Network: Risk and the Role of Place in the Transmission of Infectious Diseases

Using GPS-defined venue-based affiliation networks among Black sexually minoritized men and transgender women to identify locations for HIV prevention interventions

PURPOSE

HIV biomedical intervention uptake is suboptimal among Black sexually minoritized men (SMM) and transgender women (TW). Venues where people meet and interact shape HIV-related risk and prevention behaviors. We aimed to construct GPS-defined venue-based affiliation networks and identify the unique set of venues that could maximize reach of HIV biomedical interventions among Black SMM and TW.

METHODS

We used baseline survey and GPS data from 272 Black SMM and TW in the Neighborhoods and Networks (N2) Cohort Study in Chicago, Illinois (2018-2019). We mapped participants' GPS data to the nearest pre-identified SMM- and TW-friendly venue (n = 222) to construct affiliation networks. Network analyses were performed to identify influential venues that can yield high reach to intervention candidates.

RESULTS

Participants were affiliated with 75.5 % of all pre-identified venues based on GPS data. Two influential venues were identified in the non-PrEP use network, which when combined, could reach 52.5 % of participants not taking PrEP. Participants that could be reached through these two influential venues reported more non-main sex partners than participants not affiliated with either venue (p = 0.049).

CONCLUSION

We demonstrate a potential for GPS-defined venue-based affiliation networks to identify unique combinations of venues that could maximize the impact of HIV prevention interventions.

Novel Location-Based Survey Using Cognitive Interviews to Assess Geographic Networks and Hotspots of Sex and Drug Use: Implementation and Validation Study

BACKGROUND

The Ending the HIV Epidemic initiative in the United States relies on HIV hotspots to identify where to geographically target new resources, expertise, and technology. However, interventions targeted at places with high HIV transmission and infection risk, not just places with high HIV incidence, may be more effective at reducing HIV incidence and achieving health equity.

OBJECTIVE

We described the implementation and validation of a web-based activity space survey on HIV risk behaviors. The survey was intended to collect geographic information that will be used to map risk behavior hotspots as well as the geography of sexual networks in Los Angeles County.

METHODS

The survey design team developed a series of geospatial questions that follow a 3-level structure that becomes more geographically precise as participants move through the levels. The survey was validated through 9 cognitive interviews and iteratively updated based on participant feedback until the saturation of topics and technical issues was reached.

RESULTS

In total, 4 themes were identified through the cognitive interviews: functionality of geospatial questions, representation and accessibility, privacy, and length and understanding of the survey. The ease of use for the geospatial questions was critical as many participants were not familiar with mapping software. The inclusion of well-known places, landmarks, and road networks was critical for ease of use. The addition of a Google Maps interface, which was familiar to many participants, aided in collecting accurate and precise location information. The geospatial questions increased the length of the survey and warranted the inclusion of features to simplify it and speed it up. Using nicknames to refer to previously entered geographic locations limited the number of geospatial questions that appeared in the survey and reduced the time taken to complete it. The long-standing relationship between participants and the research team improved comfort to disclose sensitive geographic information related to drug use and sex. Participants in the cognitive interviews highlighted how trust and inclusive and validating language in the survey alleviated concerns related to privacy and representation.

CONCLUSIONS

This study provides promising results regarding the feasibility of using a web-based mapping survey to collect sensitive location information relevant to ending the HIV epidemic. Data collection at several geographic levels will allow for insights into spatial recall of behaviors as well as future sensitivity analysis of the spatial scale of hotspots and network characteristics. This design also promotes the privacy and comfort of participants who provide location information for sensitive topics. Key considerations for implementing this type of survey include trust from participants, community partners, or research teams to overcome concerns related to privacy and comfort. The implementation of similar surveys should consider local characteristics and knowledge when crafting the geospatial components.

Deep learning and social network analysis elucidate drivers of HIV transmission in a high-incidence cohort of people who inject drugs

Globally, people who inject drugs (PWID) experience some of the fastest-growing HIV epidemics. Network-based approaches represent a powerful tool for understanding and combating these epidemics; however, detailed social network studies are limited and pose analytical challenges. We collected longitudinal social (injection partners) and spatial (injection venues) network information from 2512 PWID in New Delhi, India. We leveraged network analysis and graph neural networks (GNNs) to uncover factors associated with HIV transmission and identify optimal intervention delivery points. Longitudinal HIV incidence was 21.3 per 100 person-years. Overlapping community detection using GNNs revealed seven communities, with HIV incidence concentrated within one community. The injection venue most strongly associated with incidence was found to overlap six of the seven communities, suggesting that an intervention deployed at this one location could reach the majority of the sample. These findings highlight the utility of network analysis and deep learning in HIV program design.

Sexually transmitted infections on the border between Suriname and French Guiana: A scoping review

Purpose

The Maroni basin –delineating the border between Suriname and French Guiana— presents sociocultural, geographical and economic circumstances that have been conducive to the circulation of sexually transmitted infections and to delays in diagnosis and care. Given the scarcity of published data, we aimed to describe different sexually transmitted infections along the Maroni and to gain a broader understanding of the epidemiologic situation.

Methods

We conducted a scoping review of the efforts to approach the problem of sexually transmitted infections in this complex border area. Temporal trends were plotted and crude numbers were divided by local population numbers.

Results

For HIV, despite increasing testing efforts, most patients still present at the advanced HIV stage (median CD4 count at diagnosis is < 20 per mm³), and 25% of patients in Saint Laurent du Maroni were lost to follow-up within 6 years. However, progress on both sides has led to a decline in AIDS cases and mortality. Despite a rapid increase in the 1990’s along the Maroni, the current HIV prevalence seemed lower (0.52%) in the rural villages than in coastal urban centers (> 1%). High risk HPV infection prevalence among women reaches 23.3%. The incidence of gonorrhea was 4.2 per 1,000 population aged 15-59. For chlamydiasis it was 3.4 per 1,000 population aged 15-59. For syphilis, the incidence was 2.5 per 1,000 population aged 15-59. Gonorrhea, chlamydiasis, hepatitis B detection increased over time with greater testing efforts and new diagnostic tests. Since the COVID-19 epidemic, congenital syphilis has dramatically increased in Saint Laurent du Maroni reaching 808 per 100,000 live births.

Conclusion

Sexually transmitted infections seemed more prevalent in Saint Laurent du Maroni –the sole urban center—than in the remote villages along the Maroni. The syndromic approach and the heterogeneity of diagnostic platforms presumably overlook most infections in the region. Therefore, a concerted approach and a shared diagnostic upgrade with molecular diagnosis and rapid diagnostic tests seem necessary to reduce the burden of sexually transmitted infections on both sides of the Maroni. Congenital syphilis resulting from COVID-19 disruption of health services requires urgent attention.

Social-spatial network structures and community ties of egocentric sex and confidant networks: A Chicago case study

Exploring how sexual and confidant networks overlap spatially and socially could facilitate a better understanding of sexually transmitted infection risk, as well as help identify areas for interventions. This study aims to examine how a sexual and peer-affiliate network is impacted or shaped by interconnected social relationships and spatial patterns. We used data collected from a sample of 618 young black men who have sex with men (YBMSM) and transgender women in Chicago (2013-2014) that includes partner and confidant links, geolocations, and pre-exposure prophylaxis (PrEP) awareness. We spatialize different types of social networks and examine joint social-spatial community ties to both identify and differentiate social-spatial behavioral patterns. We explore the spatial structures of the social network by comparing ego-alter network residence patterns, visualizing ego-alter community ties in aggregate, and grouping different types of dyad relationships based on their spatial structure. Findings showed overlapping social and sexual networks. Egos with partners residing in more resourced communities furthest away, with wider alter-ego power differentials, also tended to be at greatest risk. Identifying the social-spatial structures of community ties is critical to enhance our understanding of the spatial context of social relationships, and further distill risk heterogeneity in vulnerable populations within an equitable health framework.

Place-Based Correlates of Exchange Sex Among People Who Inject Drugs in 19 U.S. Metropolitan Areas, 2012

This study examined overall and gender-specific associations between place-based characteristics and opposite-sex exchange sex among people who inject drugs (PWID) in the U.S. PWID were recruited from 19 metropolitan statistical areas (MSAs) for the Centers for Disease Control and Prevention's 2012 National HIV Behavioral Surveillance. Administrative data were used to describe the economic, social, and political features of the ZIP codes, MSAs, counties, and states where PWID lived. Multilevel modeling estimated associations of place characteristics and exchange sex. We found that 52% of women and 23% of men reported past-year opposite-sex exchange sex (N = 7599). Female PWID living in states with stronger policies supporting working caregivers had lower odds of exchange sex (aOR = 0.80; 95% CI 0.69, 0.94). PWID living in ZIP codes with greater economic deprivation had higher odds of exchange sex (aOR = 1.10; 95% CI 1.03, 1.17). We found that a high percentage of male PWID exchanged sex with women; determinants and risks of this group merit exploration. If future research establishes that the relationships identified here are causal, interventions to reduce exchange sex among PWID should include policies supporting working caregivers and reducing poverty rates.

Role of direct and indirect social and spatial ties in the diffusion of HIV and HCV among people who inject drugs: a cross-sectional community-based network analysis in New Delhi, India

Background:

People who inject drugs (PWID) account for some of the most explosive human immunodeficiency virus (HIV) and hepatitis C virus (HCV) epidemics globally. While individual drivers of infection are well understood, less is known about network factors, with minimal data beyond direct ties.

Methods:

2512 PWID in New Delhi, India were recruited in 2017–19 using a sociometric network design. Sampling was initiated with 10 indexes who recruited named injection partners (people who they injected with in the prior month). Each recruit then recruited their named injection partners following the same process with cross-network linkages established by biometric data. Participants responded to a survey, including information on injection venues, and provided a blood sample. Factors associated with HIV/HCV infection were identified using logistic regression.

Results:

The median age was 26; 99% were male. Baseline HIV prevalence was 37.0% and 46.8% were actively infected with HCV (HCV RNA positive). The odds of prevalent HIV and active HCV infection decreased with each additional degree of separation from an infected alter (HIV AOR: 0.87; HCV AOR: 0.90) and increased among those who injected at a specific venue (HIV AOR: 1.50; HCV AOR: 1.69) independent of individual-level factors (p<0.001). In addition, sociometric factors, for example, network distance to an infected alter, were statistically significant predictors even when considering immediate egocentric ties.

Conclusions:

These data demonstrate an extremely high burden of HIV and HCV infection and a highly interconnected injection and spatial network structure. Incorporating network and spatial data into the design/implementation of interventions may help interrupt transmission while improving efficiency.

Funding:

National Institute on Drug Abuse and the Johns Hopkins University Center for AIDS Research.

Understanding the social and spatial relationships that connect people is a key element to stop the spread of infectious diseases. These networks are particularly relevant to combat epidemics among populations that are hard to reach with public health interventions. Network-based approaches, for example, can help to stop HIV or hepatitis C from spreading amongst populations that use injectable drugs. Yet how social and geographic connections such as acquaintances, injection partners, or preferred drug use places impact the risk of infection is still poorly mapped out.

To address this question, Clipman et al. focused on people who inject drugs in New Delhi, India, a population heavily impacted by HIV and hepatitis C. Over 2500 people were recruited, each participant inviting their injection partners to also take part. The volunteers answered survey questions, including where they used drugs, and provided a blood sample to be tested.

The results showed that, even after adjusting for individual risk factors, where people used drugs and with whom affected their risk of becoming infected with HIV and hepatitis C. In terms of social ties, the likelihood of HIV and hepatitis C infection decreased by about 13% for each person separating a given individual from an infected person. However, geographical networks also had a major impact. Injecting at a popular location respectively increased the odds of HIV and hepatitis C infection by 50% and 69%. In fact, even if the participant was not using drugs at these specific places, having an injection partner who did was enough to increase the risk for disease: for each person separating an individual from the location, the likelihood of being infected with HIV and hepatitis C decreased by respectively 14% and 10%.

The results by Clipman et al. highlight how the relationships between physical spaces and social networks contribute to the spread of dangerous diseases amongst people who inject drugs. Ultimately, this knowledge may help to shape better public health interventions that would take into account the importance of geographical locations.

Sexually Transmitted Infections in Association With Area-Level Prostitution and Drug-Related Arrests

OBJECTIVES

This study aimed to examine the mediators and moderators of area-level prostitution arrests and sexually transmitted infections (STIs) using population-level data.

METHODS

Using justice and public health STI/HIV data in Marion County (Indianapolis), Indiana, during an 18-year period, we assessed the overall association of area-level prostitution and drug-related arrests and STI/HIV, and mediators and moderators of the relationship. Point-level arrests were geocoded and aggregated by a census block group.

RESULTS

Results indicate a positive relationship between numbers of prostitution arrests and area-level STI rates. There was a dose-response relationship between prostitution arrests and STI rates when accounting for drug-related arrests. The highest quintile block groups had significantly higher rates of reported chlamydia (incident rate ratio [IRR], 3.29; 95% confidence interval [CI], 2.82-3.84), gonorrhea (IRR, 4.73; 95% CI, 3.90-5.57), syphilis (IRR, 4.28; 95% CI, 3.47-5.29), and HIV (IRR, 2.76; 95% CI, 2.24-3.39) compared with the lowest quintile. When including drug arrests, the second (IRR, 1.19; 95% CI, 1.03-1.38) and the third (IRR, 1.20; 95% CI, 1.02-1.41) highest quintile block groups had lower IRR for reported rates of chlamydia, indicating that drug arrests mediated the prostitution arrest effect.

CONCLUSIONS

These findings inform public health agencies and community-based organizations that conduct outreach in these areas to expand their efforts to include harm reduction and HIV/STI testing for both sex workers and individuals experiencing substance use disorder. Another implication of these data is the importance of greater collaboration in public health and policing efforts to address overlapping epidemics that engage both health and legal interventions.

Social network support and harm reduction activities in a peer researcher-led pilot study, British Columbia, Canada

Background

People who smoke drugs (PWSD) are at high risk of both infectious disease and overdose. Harm reduction activities organized by their peers in the community can reduce risk by providing education, safer smoking supplies, and facilitate access to other services. Peers also provide a network of people who provide social support to PWSD which may reinforce harm reducing behaviors. We evaluated the numbers of supportive network members and the relationships between received support and participants’ harm-reducing activities.

Methods

Initial peer-researchers with past or current lived drug use experience were employed from communities in Abbotsford and Vancouver to interview ten friends from their social networks who use illegal drugs mainly through smoking. Contacts completed a questionnaire about people in their own harm reduction networks and their relationships with each other. We categorized social support into informational, emotional, and tangible aspects, and harm reduction into being trained in the use of, or carrying naloxone, assisting peers with overdoses, using brass screens to smoke, obtaining pipes from service organizations and being trained in CPR.

Results

Fifteen initial peer researchers interviewed 149 participants who provided information on up to 10 people who were friends or contacts and the relationships between them. People who smoked drugs in public were 1.46 (95% CI, 1.13-1.78) more likely to assist others with possible overdoses if they received tangible support; women who received tangible support were 1.24 (95% CI; 1.02-1.45) more likely to carry and be trained in the use of naloxone. There was no relationship between number of supportive network members and harm reduction behaviors.

Conclusions

In this pilot study, PWSD who received tangible support were more likely to assist peers in possible overdoses and be trained in the use of and/or carry naloxone, than those who did not receive tangible support. Future work on the social relationships of PWSD may prove valuable in the search for credible and effective interventions.

The Social Geography of Partner Selection in Toronto, Canada: A Qualitative Description of "Convection Mixing"

The geographic distribution of sexually transmitted infections reflects the underlying social process of sexual partner selection. This qualitative study explored the social geography of partner selection among sexual minority men and used the results to develop a mid-range theory of STI transmission. In-depth interviews with 31 sexual minority men who lived, worked, or socialized in Toronto, Canada, occurred in June and July 2016. Participants were asked how they found sexual partners and reconstructed their egocentric sexual networks for the previous 3 months. Participants described an iterative process of partner selection involving intention (sex versus dating), connecting with community, and selecting a partner based on intersecting partner characteristics (external, internal, and emergent feelings when interacting with potential partners) and personal preferences. Geography influenced partner selection three ways: (1) participant search patterns maximized the number of potential partners in the shortest distance possible; (2) the density of sexual minority men in a participant's community directly impacted participant's social and sexual isolations; and (3) geosexual isolation influenced sexual mixing patterns. Participants described "convection mixing," where assortative urban mixing nested within disassortative suburban mixing resulted in movement from the suburbs to downtown and back to the suburbs. We theorize that convection mixing may be contributing to the persistence of STI epidemics in core and outbreak areas by creating STI reservoirs outside of, and connected to, core and outbreak areas.

Youth perspectives on sexual health education: Voices from the YEP study in Toronto

The Youth Engagement Project (YEP) is a community-based pilot study in Toronto, Canada that we developed to better understand perspectives about and experiences of sexual health education among socioeconomically marginalized, racialized, and LGBTQ youth. We investigated: 1) what sex-related messages these young people received as they grew up, 2) how those messages affected their perspectives and sexual behaviour, and 3) their recommendations for sexual health education that meets their needs. Engaging youth whose voices are often overlooked due to their low socioeconomic status and their racial, sexual, and religious identities, and using a place-based method, we recruited a total of 47 young people, aged 16–24, and divided them into six groups based on gender and residential neighbourhood. The data was collected through a demographic and sexual practice survey, followed by a series of two focus groups. We conducted thematic analysis, guided by a socio-ecological approach and paying particular attention to participants’ intrapersonal, interpersonal and environmental factors. Our results indicate that participants received inadequate and contradictory sexuality related information from multiple sources. These mixed messages contributed to confusion, misconceptions, distress, and sexual vulnerabilities. Youth expressed their need for more inclusive and relevant sexual health education starting from an early age, more support for parents and teachers to help them talk with children and youth about sexuality, and more youth-driven integrated health promotion programs to allow them to make informed choices. Their voices and perspectives are useful in informing inclusive and youth-centred sexual health education at home, in school and in the community.

Contextualizing condoms: a cross-sectional study mapping intersections of locations of sexual contact, partner type, and substance use as contexts for sexual risk behavior among MSM in Peru

Background

Condomless anal intercourse (CAI) appears to be increasing among men who have sex with men (MSM) globally, and is reported to be as high as 70% in recent studies in Peru. To improve understanding of the evolving context of CAI among MSM in Peru, we studied associations between partner type, substance use, and condomless anal intercourse (CAI) in locations where MSM commonly report having sexual encounters.

Methods

In a 2017 cross-sectional study of rectal STI screening and HIV prevention, a convenience sample of MSM recruited from community venues in Lima completed a survey of demographic characteristics and sexual risk behavior with their three most recent partners. Generalized estimating equations estimated correlations of CAI with location of last sexual contact, participant substance use prior to sex, and negotiation of condom use before or during sex. The network data integration application, Cytoscape, mapped intersections of partner type, sexual orientation, substance use, and CAI by four types of locations where sex occurred: 1) Home, 2) Hotel, 3) Sauna or Internet Cabin, and 4) Public Spaces.

Results

Of 447 MSM (median age 27 years), 76.9% reported CAI with ≥1 of their last three partners. Participants reported sex with casual partners most commonly in homes (64.6%) and hotels (60.4%), and with anonymous partners most often in saunas/Internet cabins (57.5%) and public spaces (52.6%). CAI was less commonly reported in hotels (aPR, 95% CI: 0.85, 0.75–0.97) compared to homes. Participants who used marijuana before sex at home were more likely to report CAI than MSM who did not use marijuana (1.36, 1.01–1.92). Partner alcohol use before sex was associated with CAI in saunas/Internet cabins (3.17, 1.45–6.91) and public spaces (2.65, 1.41–4.98). In the sexual network maps, almost all MSM who used drugs prior to their sexual encounters used drugs with more than one of their last three partners.

Conclusions

CAI was common and associated with different risk factors, like partner type and substance use, based on location where sex occurred. Novel combination HIV, STI, and substance use prevention interventions must consider how the social environments of MSM influence condom use and other sexual risk behaviors.

Trial registration

ClinicalTrials.gov Identifier NCT03010020, January 4, 2017.

Conceptualizing Geosexual Archetypes: Mapping the Sexual Travels and Egocentric Sexual Networks of Gay and Bisexual Men in Toronto, Canada

Six geosexual archetypes were identified: hosters, house-callers, rovers, privates, travellers, and geoflexibles, each with different characteristic profiles. Prioritizing interventions to hosters, rovers, and geoflexibles may reduce sexually transmitted infection transmission.

Supplemental digital content is available in the text.

Background

There are complex, synergistic, and persistent sexually transmitted infection (STI) epidemics affecting gay, bisexual and other men who have sex with men (gbMSM) in every major urban centre across North America. We explored the spatial architecture of egocentric sexual networks for gbMSM in Toronto, Canada.

Methods

Our integrative mixed methods study included in-depth interviews with 31 gbMSM between May and July 2016. During interviews, participants mapped their egocentric sexual network for the preceding 3 months geographically. At the end, a self-administered survey was used to collect sociodemographic characteristics, online technology use, and STI testing and history.

Results

We identified 6 geosexual archetypes: hosters, house-callers, privates, rovers, travellers, and geoflexibles. Hosters always, or almost always (≥80%), hosted sex at their home. House-callers always, or almost always (≥80%), had sex at their partner’s home. Rovers always or almost always (≥80%) had sex at public venues (eg, bath houses, sex clubs) and other public spaces (eg, parks, cruising sites). Privates had sex in private—their own home or their partner's (part hoster, part house-caller). Travellers had sex away from their home, either at a partner’s home or some other venue or public space (part house-caller, part rover). Geoflexibles had sex in a variety of locations—their home, their partner’s home, or public venues. All hosters and rovers, and to a lesser extent, geoflexibles, reported a history of syphilis and human immunodeficiency virus.

Conclusions

Prioritizing interventions to hosters, rovers, and geoflexibles may have an important impact on reducing STI transmission.

Social Networks of Substance-Using Populations: Key Issues and Promising New Approaches for HIV

PURPOSE OF REVIEW

This paper presents recent literature on substance using networks and HIV, highlighting renewed and emerging themes in the field. The goal is to draw attention to research that holds considerable promise for advancing our understanding of the role of networks in shaping behaviors, while also providing critical information for the development of interventions, programs, and policies to reduce HIV and other drug-related harms.

RECENT FINDINGS

Recent research advances our understanding of networks and HIV, including among understudied populations, and provides new insight into how risk environments shape the networks and health of substance-using populations. In particular, the integration of network approaches with molecular epidemiology, research on space and place, and intervention methods provides exciting new avenues of investigation. Continued advances in network research are critical to supporting the health and rights of substance-using populations and ensuring the development of high-impact HIV programs and policies.

Enhancing the sample diversity of snowball samples: Recommendations from a research project on anti-dam movements in Southeast Asia

Snowball sampling is a commonly employed sampling method in qualitative research; however, the diversity of samples generated via this method has repeatedly been questioned. Scholars have posited several anecdotally based recommendations for enhancing the diversity of snowball samples. In this study, we performed the first quantitative, medium-N analysis of snowball sampling to identify pathways to sample diversity, analysing 211 reach-outs conducted via snowball sampling, resulting in 81 interviews; these interviews were administered between April and August 2015 for a research project on anti-dam movements in Southeast Asia. Based upon this analysis, we were able to refine and enhance the previous recommendations (e.g., showcasing novel evidence on the value of multiple seeds or face-to-face interviews). This paper may thus be of particular interest to scholars employing or intending to employ snowball sampling.

Bio-behavioral survey of syphilis in homeless men in Central Brazil: a cross-sectional study

The objective of this study was to investigate the prevalence and factors associated with syphilis in homeless men in Central Brazil. It is a cross-sectional study conducted with 481 individuals attending four therapeutic communities between October and December 2015. A structured interview was conducted to collect sociodemographic data and risk factors for syphilis. Rapid/point-of-care and VDRL tests were performed to determine exposure to syphilis and the presence of active syphilis, respectively. Poisson regression analysis was used to verify the risk factors associated with the outcomes investigated. Of the study participants, 10.2% were reactive to the rapid test, and 5.4% had active syphilis. At the multiple regression analysis, schooling (adjusted prevalence ratio - APR: 0.89; p = 0.005), history of genital ulcer (APR: 2.59; p = 0.002), STI history (APR: 1.97; p = 0.042), and sexual intercourse under drug effects (APR: 1.60; p = 0.022) were independent factors associated with lifetime syphilis. Also, history of genital ulcer (APR: 2.19; p = 0.019), STI history (APR: 1.74; p = 0.033) and number of sexual partners in the last year (APR: 1.02; p = 0.044) were associated with active syphilis. The prevalence of syphilis among homeless men was rather high, confirming the vulnerability of this group to this infection. These results emphasize the need for educational intervention, improvement of risk reduction programs, availability of diagnostic tests, especially the rapid test, and treatment.

Advances in spatial epidemiology and geographic information systems

The field of spatial epidemiology has evolved rapidly in the past 2 decades. This study serves as a brief introduction to spatial epidemiology and the use of geographic information systems in applied research in epidemiology. We highlight technical developments and highlight opportunities to apply spatial analytic methods in epidemiologic research, focusing on methodologies involving geocoding, distance estimation, residential mobility, record linkage and data integration, spatial and spatio-temporal clustering, small area estimation, and Bayesian applications to disease mapping. The articles included in this issue incorporate many of these methods into their study designs and analytical frameworks. It is our hope that these studies will spur further development and utilization of spatial analysis and geographic information systems in epidemiologic research.