Spatiotemporal transmission and determinants of typhoid and paratyphoid fever in Hongta District, Yunnan Province, China

PLoS Negl Trop Dis. 2013;7(3):e2112. doi: 10.1371/journal.pntd.0002112. Epub 2013 Mar 14.

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.

Methods and findings: 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.

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • China / epidemiology
  • Cluster Analysis
  • Female
  • Geography
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Paratyphoid Fever / epidemiology*
  • Paratyphoid Fever / transmission*
  • Prevalence
  • Seasons
  • Socioeconomic Factors
  • Soil Microbiology
  • Typhoid Fever / epidemiology*
  • Typhoid Fever / transmission*
  • Vegetables / microbiology
  • Wastewater / microbiology
  • Young Adult

Substances

  • Waste Water

Grants and funding

This study was supported by the following grants: MOST (2012CB955503; 2011AA120305; 2009ZX10004-201; 200802025), and NSFC (41023010; 41271404). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.