Spatiality, Temporality, and Contexts: Geosocial Data as Evidence of Social Interactions and Networks

Spatio-Temporal Constraints on Social Networks Workshop, University of California, Santa Barbara, Center for Spatial Studies, 13-14 December 2010

Sarah Elwood

“My interest in and contributions to this specialist meeting stem from two strands of my past research: my long-term focus on the use of geospatial technologies at the grassroots, by laypersons; and more recent work on volunteered geographic information and qualitative GIS.

“From these perspectives, I read the call for participation as implicitly pointing to the latest in a series of developments through which the Internet has dramatically altered human communication and social networks: The rising use of online social networking sites, especially those that include a geographic component. Specifically, I refer to services that document network members’ presence in or preferences for particular places or locations (as in FourSquare’s “check in” function), or that enable geolocating of user-generated content shared through a social networking service (as in Twitter’s geoAPI). As these services have proliferated and the data streams flowing from them exponentially increased, there is growing interest in how these data might be used for a variety of purposes—improving real-time emergency response, investigating new forms of social life and social capital, or fighting terrorism to name a few.”

Quantifying the Spatial Dimension of Dengue Virus Epidemic Spread within a Tropical Urban Environment

PLoS Neglected Tropical Diseases, December 2010

Gonzalo M. Vazquez-Prokopec, Uriel Kitron, Brian Montgomery, Peter Horne, and Scott A. Ritchie

“Background: Dengue infection spread in naive populations occurs in an explosive and widespread fashion primarily due to the absence of population herd immunity, the population dynamics and dispersal of Ae. aegypti, and the movement of individuals within the urban space. Knowledge on the relative contribution of such factors to the spatial dimension of dengue virus spread has been limited. In the present study we analyzed the spatio-temporal pattern of a large dengue virus-2 (DENV-2) outbreak that affected the Australian city of Cairns (north Queensland) in 2003, quantified the relationship between dengue transmission and distance to the epidemic’s index case (IC), evaluated the effects of indoor residual spraying (IRS) on the odds of dengue infection, and generated recommendations for city-wide dengue surveillance and control.

“Methods and Findings: We retrospectively analyzed data from 383 DENV-2 confirmed cases and 1,163 IRS applications performed during the 25-week epidemic period. Spatial (local k-function, angular wavelets) and space-time (Knox test) analyses quantified the intensity and directionality of clustering of dengue cases, whereas a semi-parametric Bayesian space-time regression assessed the impact of IRS and spatial autocorrelation in the odds of weekly dengue infection. About 63% of the cases clustered up to 800 m around the IC’s house. Most cases were distributed in the NW-SE axis as a consequence of the spatial arrangement of blocks within the city and, possibly, the prevailing winds. Space-time analysis showed that DENV-2 infection spread rapidly, generating 18 clusters (comprising 65% of all cases), and that these clusters varied in extent as a function of their distance to the IC’s residence. IRS applications had a significant protective effect in the further occurrence of dengue cases, but only when they reached coverage of 60% or more of the neighboring premises of a house.

“Conclusion: By applying sound statistical analysis to a very detailed dataset from one of the largest outbreaks that affected the city of Cairns in recent times, we not only described the spread of dengue virus with high detail but also quantified the spatio-temporal dimension of dengue virus transmission within this complex urban environment. In areas susceptible to non-periodic dengue epidemics, effective disease prevention and control would depend on the prompt response to introduced cases. We foresee that some of the results and recommendations derived from our study may also be applicable to other areas currently affected or potentially subject to dengue epidemics.”

Free Webinar on GIS and DIMP: A Solid Plan to Address DIMP and Improve Operations

February 23, 2011
11:00 a.m.-noon (PST)

Be part of the first webinar in a five-part series to explore what GIS offers to distribution integrity management programs (DIMP). This webinar provides an overview of GIS for such programs and will include a case study from one utility that has used GIS for DIMP.

Benefits of the upcoming event include the following:

  • Learn how to use GIS for distribution risk assessment and field data collection.
  • Find out how GIS can help you document and demonstrate an understanding of your system.

Beyond DIMP, see how GIS can help you meet key performance indicators without any additional investment.

Register now