title: Genotypic and Spatial Analysis of Mycobacterium tuberculosis Transmission in a High-Incidence Urban Setting.
abstract: BACKGROUND
  Genotyping Mycobacterium tuberculosis isolates allows study of dynamics of tuberculosis transmission, while geoprocessing allows spatial analysis of clinical and epidemiological data. Here, genotyping data and spatial analysis were combined to characterize tuberculosis transmission in Vitória, Brazil, to identify distinct neighborhoods and risk factors associated with recent tuberculosis transmission.
  
  
  METHODS
  From 2003 to 2007, 503 isolates were genotyped by IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping. The analysis included kernel density estimation, K-function analysis, and a t test distance analysis. Mycobacterium tuberculosis isolates belonging to identical RFLP patterns (clusters) were considered to represent recent tuberculosis infection (cases).
  
  
  RESULTS
  Of 503 genotyped isolates, 242 (48%) were categorized into 70 distinct clusters belonging to 12 RFLP families. The proportion of recent transmission was 34.2%. Kernel density maps indicated 3 areas of intense concentration of cases. K-function analysis of the largest RFLP clusters and families showed they co-localized in space. The distance analysis confirmed these results and demonstrated that unique strain patterns (controls) randomly distributed in space. A logit model identified young age, positive smear test, and lower Index of Quality of Urban Municipality as risk factors for recent transmission. The predicted probabilities for each neighborhood were mapped and identified neighborhoods with high risk for recent transmission.
  
  
  CONCLUSIONS
  Spatial and genotypic clustering of M. tuberculosis isolates revealed ongoing active transmission of tuberculosis caused by a small subset of strains in specific neighborhoods of the city. Such information provides an opportunity to target tuberculosis transmission control, such as through rigorous and more focused contact investigation programs.
authors.affiliation: Graduate Program in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Fabíola Karla Correa
authors.initials: FK
authors.lastname: Ribeiro
authors.affiliation: Duke Global Health Institute and Nicholas School of Environment, Duke University, Durham, North Carolina.
authors.forename: William
authors.initials: W
authors.lastname: Pan
authors.affiliation: Department of Statistics, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Adelmo
authors.initials: A
authors.lastname: Bertolde
authors.affiliation: Graduate Program in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Solange Alves
authors.initials: SA
authors.lastname: Vinhas
authors.affiliation: Graduate Program in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Renata Lyrio
authors.initials: RL
authors.lastname: Peres
authors.affiliation: Division of Infectious Disease and Vaccinology, School of Public Health, University of California, Berkeley.
authors.forename: Lee
authors.initials: L
authors.lastname: Riley
authors.affiliation: Graduate Program in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Moisés
authors.initials: M
authors.lastname: Palaci
authors.affiliation: Graduate Program in Public Health, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Ethel Leonor
authors.initials: EL
authors.lastname: Maciel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D062206:Spatial Analysis; D014376:Tuberculosis / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission*; D014505:Urban Population; D055815:Young Adult
keywords: molecular epidemiology; spatial analysis; transmission; tuberculosis