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Shifts in the spatiotemporal dynamics of schistosomiasis: a case study in Anhui Province, China.

Hu Y, Li R, Chen Y, Gao F, Wang Q, Zhang S, Zhang Z, Jiang Q - PLoS Negl Trop Dis (2015)

Bottom Line: Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997-2010 in Anhui Province, East China.The POPs associated with these oscillatory components showed that the pattern near the Yangtze River varied markedly and that the disease risk appeared to evolve in a Southwest/Northeast orientation.The POP coefficients showed decreasing tendency until 2001, then increasing during 2002-2005 and decaying afterwards.

View Article: PubMed Central - PubMed

Affiliation: Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China.

ABSTRACT

Background: The Chinese national surveillance system showed that the risk of Schistosoma japonicum infection fluctuated temporally. This dynamical change might indicate periodicity of the disease, and its understanding could significantly improve targeted interventions to reduce the burden of schistosomiasis. The goal of this study was to investigate how the schistosomiasis risk varied temporally and spatially in recent years.

Methodology/principal findings: Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997-2010 in Anhui Province, East China. A multivariate autoregressive model, combined with principal oscillation pattern (POP) analysis, was used to evaluate the spatio-temporal variation of schistosomiasis risk. Results showed that the temporal changes of schistosomiasis risk in the study area could be decomposed into two sustained damped oscillatory modes with estimated period of approximately 2.5 years. The POPs associated with these oscillatory components showed that the pattern near the Yangtze River varied markedly and that the disease risk appeared to evolve in a Southwest/Northeast orientation. The POP coefficients showed decreasing tendency until 2001, then increasing during 2002-2005 and decaying afterwards.

Conclusion: The POP analysis characterized the variations of schistosomiasis risk over space and time and demonstrated that the disease mainly varied temporally along the Yangtze River. The schistosomiasis risk declined periodically with a temporal fluctuation. Whether it resulted from previous national control strategies on schistosomiasis needs further investigations.

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Related in: MedlinePlus

The first normal modes plotted spatially for the matrix M.As POP2 and POP1 are conjugate vectors, only POP1 is shown for the pair. Open circles denote negative values, while circles with pluses represent positive values; larger circles imply larger magnitude and small circles are values close to zero. The center points of the circles are located on centroids of county polygons. The shift of the spatial pattern of the disease within one period could be described from left to right. The maps were created using ArcGIS software (version 10.0, ESRI Inc. Redlands, CA).
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pntd.0003715.g006: The first normal modes plotted spatially for the matrix M.As POP2 and POP1 are conjugate vectors, only POP1 is shown for the pair. Open circles denote negative values, while circles with pluses represent positive values; larger circles imply larger magnitude and small circles are values close to zero. The center points of the circles are located on centroids of county polygons. The shift of the spatial pattern of the disease within one period could be described from left to right. The maps were created using ArcGIS software (version 10.0, ESRI Inc. Redlands, CA).

Mentions: The POPs associated with oscillatory components are displayed in Fig 6. It illustrates the evolving spatial patterns of POP1 as indicated in (3). The POP showed a similar trend that there was a large variation in areas close to the Yangtze River. An interesting feature is that the pattern of the disease risk appeared to evolve in a Southwest/Northeast orientation. Fig 7 shows the POP coefficients (at(k)) associated with POPs in Fig 6. The plot, as a whole, shows a damped but fluctuated trend. The time series associated with POP1 showed decreasing amplitude until 2001, then increasing amplitude during 2002–2005 and decaying amplitude afterwards. The time series showed short and decaying amplitude at the end of the study period.


Shifts in the spatiotemporal dynamics of schistosomiasis: a case study in Anhui Province, China.

Hu Y, Li R, Chen Y, Gao F, Wang Q, Zhang S, Zhang Z, Jiang Q - PLoS Negl Trop Dis (2015)

The first normal modes plotted spatially for the matrix M.As POP2 and POP1 are conjugate vectors, only POP1 is shown for the pair. Open circles denote negative values, while circles with pluses represent positive values; larger circles imply larger magnitude and small circles are values close to zero. The center points of the circles are located on centroids of county polygons. The shift of the spatial pattern of the disease within one period could be described from left to right. The maps were created using ArcGIS software (version 10.0, ESRI Inc. Redlands, CA).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4400088&req=5

pntd.0003715.g006: The first normal modes plotted spatially for the matrix M.As POP2 and POP1 are conjugate vectors, only POP1 is shown for the pair. Open circles denote negative values, while circles with pluses represent positive values; larger circles imply larger magnitude and small circles are values close to zero. The center points of the circles are located on centroids of county polygons. The shift of the spatial pattern of the disease within one period could be described from left to right. The maps were created using ArcGIS software (version 10.0, ESRI Inc. Redlands, CA).
Mentions: The POPs associated with oscillatory components are displayed in Fig 6. It illustrates the evolving spatial patterns of POP1 as indicated in (3). The POP showed a similar trend that there was a large variation in areas close to the Yangtze River. An interesting feature is that the pattern of the disease risk appeared to evolve in a Southwest/Northeast orientation. Fig 7 shows the POP coefficients (at(k)) associated with POPs in Fig 6. The plot, as a whole, shows a damped but fluctuated trend. The time series associated with POP1 showed decreasing amplitude until 2001, then increasing amplitude during 2002–2005 and decaying amplitude afterwards. The time series showed short and decaying amplitude at the end of the study period.

Bottom Line: Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997-2010 in Anhui Province, East China.The POPs associated with these oscillatory components showed that the pattern near the Yangtze River varied markedly and that the disease risk appeared to evolve in a Southwest/Northeast orientation.The POP coefficients showed decreasing tendency until 2001, then increasing during 2002-2005 and decaying afterwards.

View Article: PubMed Central - PubMed

Affiliation: Department of Epidemiology, School of Public Health, Fudan University, Shanghai, China; Key Laboratory of Public Health Safety, Ministry of Education, Shanghai, China; Laboratory for Spatial Analysis and Modeling, School of Public Health, Fudan University, Shanghai, China.

ABSTRACT

Background: The Chinese national surveillance system showed that the risk of Schistosoma japonicum infection fluctuated temporally. This dynamical change might indicate periodicity of the disease, and its understanding could significantly improve targeted interventions to reduce the burden of schistosomiasis. The goal of this study was to investigate how the schistosomiasis risk varied temporally and spatially in recent years.

Methodology/principal findings: Parasitological data were obtained through repeated cross-sectional surveys that were carried out during 1997-2010 in Anhui Province, East China. A multivariate autoregressive model, combined with principal oscillation pattern (POP) analysis, was used to evaluate the spatio-temporal variation of schistosomiasis risk. Results showed that the temporal changes of schistosomiasis risk in the study area could be decomposed into two sustained damped oscillatory modes with estimated period of approximately 2.5 years. The POPs associated with these oscillatory components showed that the pattern near the Yangtze River varied markedly and that the disease risk appeared to evolve in a Southwest/Northeast orientation. The POP coefficients showed decreasing tendency until 2001, then increasing during 2002-2005 and decaying afterwards.

Conclusion: The POP analysis characterized the variations of schistosomiasis risk over space and time and demonstrated that the disease mainly varied temporally along the Yangtze River. The schistosomiasis risk declined periodically with a temporal fluctuation. Whether it resulted from previous national control strategies on schistosomiasis needs further investigations.

Show MeSH
Related in: MedlinePlus