title: Spatiotemporal transmission and determinants of typhoid and paratyphoid fever in Hongta District, Yunnan Province, China.
abstract: BACKGROUND
  Typhoid and paratyphoid fever are endemic in Hongta District and their prevalence, at 113 per 100,000 individuals, remains the highest in China. However, the exact sources of the disease and its main epidemiological characteristics have not yet been clearly identified.
  
  
  RESULTS
  Numbers of typhoid and paratyphoid cases per day during the period 2006 to 2010 were obtained from the Chinese Center of Disease Control (CDC). A number of suspected disease determinants (or their proxies), were considered for use in spatiotemporal analysis: these included locations of discharge canals and food markets, as well as socio-economic and environmental factors. Results showed that disease prevalence was spatially clustered with clusters decreasing with increasing distance from markets and discharge canals. More than half of the spatial variance could be explained by a combination of economic conditions and availability of health facilities. Temporal prevalence fluctuations were positively associated with the monthly precipitation series. Polluted hospital and residential wastewater was being discharged into rainwater canals. Salmonella bacteria were found in canal water, on farmland and on vegetables sold in markets.
  
  
  CONCLUSIONS
  DISEASE TRANSMISSION IN HONGTA DISTRICT IS DRIVEN PRINCIPALLY BY TWO SPATIOTEMPORALLY COUPLED CYCLES: one involving seasonal variations and the other the distribution of polluted farmland (where vegetables are grown and sold in markets). Disease transmission was exacerbated by the fact that rainwater canals were being used for disposal of polluted waste from hospitals and residential areas. Social factors and their interactions also played a significant role in disease transmission.
authors.affiliation: State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China. wangjf@Lreis.ac.cn
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: George
authors.initials: G
authors.lastname: Christakos
authors.forename: Jun-Ling
authors.initials: JL
authors.lastname: Sun
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Fu
authors.forename: Yu-Qiong
authors.initials: YQ
authors.lastname: Shi
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D005260:Female; D005843:Geography; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010284:Paratyphoid Fever / Q000453:epidemiology* / Q000635:transmission*; D015995:Prevalence; D012621:Seasons; D012959:Socioeconomic Factors; D012988:Soil Microbiology; D014435:Typhoid Fever / Q000453:epidemiology* / Q000635:transmission*; D014675:Vegetables / Q000382:microbiology; D062065:Wastewater / Q000382:microbiology; D055815:Young Adult
chemical_list: D062065:Wastewater