title: The household distribution of trachoma in a Tanzanian village: an application of GIS to the study of trachoma.
abstract: The distribution of active trachoma in Kahe Mpya, Tanzania, an endemic village of approximately 1000 people, was mapped spatially and analysed for associated risk factors and evidence of clustering. An association between distance to water source and active disease was demonstrated, although this was reduced after accounting for the lack of independence between cases in the same household. Significant clustering of active trachoma within households was demonstrated, adding support to the hypothesized importance of intra-familial transmission. The spatial distribution of trachoma was analysed using the spatial scan statistic, and evidence of clustering of active trachoma cases detected. Understanding the distribution of the disease has implications for understanding the dynamics of transmission and therefore appropriate control activities. The demonstrated spatial clustering suggests inter-familial as well as intra-familial transmission of infection may be common in this setting. The association between active trachoma and geographical information system (GIS) measured distance to water may be relevant for planning control measures.
authors.affiliation: London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK. sarah.polack@lshtm.ac.uk
authors.forename: S R
authors.initials: SR
authors.lastname: Polack
authors.forename: A W
authors.initials: AW
authors.lastname: Solomon
authors.forename: N D E
authors.initials: ND
authors.lastname: Alexander
authors.forename: P A
authors.initials: PA
authors.lastname: Massae
authors.forename: S
authors.initials: S
authors.lastname: Safari
authors.forename: J F
authors.initials: JF
authors.lastname: Shao
authors.forename: A
authors.initials: A
authors.lastname: Foster
authors.forename: D C
authors.initials: DC
authors.lastname: Mabey
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D019353:Endemic Diseases; D005260:Female; D040362:Geographic Information Systems; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods; D015995:Prevalence; D012111:Residence Characteristics; D012423:Rural Health; D017678:Sex Distribution; D013636:Tanzania / Q000453:epidemiology; D014038:Toilet Facilities; D014141:Trachoma / Q000453:epidemiology*; D014881:Water Supply / Q000592:standards