title: Topography as a contextual variable in infectious disease transmission.
abstract: OBJECTIVE
  This paper examines whether or not topography is a contextual variable that indirectly influences the transmission of infectious diseases. Age, gender, race/ethnicity, education level, economic status, injection drug use, and high-risk sexual behavior are known to influence infectious diseases transmission, but the effects of topography are often overlooked.
  
  
  METHODS
  A sample of 395 drug users were chosen from census tracts based upon a target profile of drug use behavior and demographics for the city of Houston. HIV was chosen as the infectious disease used to test this hypothesis.
  
  
  METHODS
  Residents of 16 census tracts in Houston, Texas participated in this study.
  
  
  RESULTS
  The findings revealed that census tracts that were 'isolated' by topographic barriers, such as bayous, parks, railroad tracks, railway yards, major thoroughfares, freeways, and unique street grids had fewer cases of HIV than census tracks that were more accessible to thru-traffic.
  
  
  CONCLUSIONS
  The research findings suggest that future research studies should consider topography as being contextually related to infectious disease transmission.
authors.affiliation: Affiliated Systems Corporation, Houston, TX 77027-6022, USA. imontoya@affiliatedsystems.com
authors.forename: Isaac D
authors.initials: ID
authors.lastname: Montoya
mesh_terms: D000293:Adolescent; D000328:Adult; D003141:Communicable Diseases / Q000453:epidemiology* / Q000635:transmission*; D016021:Epidemiologic Studies; D015658:HIV Infections / Q000635:transmission; D006801:Humans; D012307:Risk Factors; D019966:Substance-Related Disorders; D019371:Topography, Medical