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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

Correlation of residuals from the formula (1).Top left: autocorrelation for PC1; Top right: cross-correlation between PC1 and PC2 (positive lag); Bottom right: cross-correlation between PC1 and PC2 (negative lag); Bottom right: autocorrelation for PC2. Horizontal dashed lines represent 95% confidence levels for correlation of white noise realizations. Lags are spaced by one year.
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pntd.0003715.g005: Correlation of residuals from the formula (1).Top left: autocorrelation for PC1; Top right: cross-correlation between PC1 and PC2 (positive lag); Bottom right: cross-correlation between PC1 and PC2 (negative lag); Bottom right: autocorrelation for PC2. Horizontal dashed lines represent 95% confidence levels for correlation of white noise realizations. Lags are spaced by one year.

Mentions: Uncorrelatedness of the residuals in formula (1) is a primary criterion for checking the adequacy of an estimated model. The autocorrelation function (ACF) for residuals of the first (the top left in Fig 5) and second PCs (the bottom right in Fig 5) indicates that the model yields an uncorrelated residual series. The rest of Fig 5 show that the estimated model is able to describe the relationship between the first and second components of the observed field yielding uncorrelated residual series. Similar analyses were carried out for the rest of PCs and uncorrelated residuals were found.


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)

Correlation of residuals from the formula (1).Top left: autocorrelation for PC1; Top right: cross-correlation between PC1 and PC2 (positive lag); Bottom right: cross-correlation between PC1 and PC2 (negative lag); Bottom right: autocorrelation for PC2. Horizontal dashed lines represent 95% confidence levels for correlation of white noise realizations. Lags are spaced by one year.
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0003715.g005: Correlation of residuals from the formula (1).Top left: autocorrelation for PC1; Top right: cross-correlation between PC1 and PC2 (positive lag); Bottom right: cross-correlation between PC1 and PC2 (negative lag); Bottom right: autocorrelation for PC2. Horizontal dashed lines represent 95% confidence levels for correlation of white noise realizations. Lags are spaced by one year.
Mentions: Uncorrelatedness of the residuals in formula (1) is a primary criterion for checking the adequacy of an estimated model. The autocorrelation function (ACF) for residuals of the first (the top left in Fig 5) and second PCs (the bottom right in Fig 5) indicates that the model yields an uncorrelated residual series. The rest of Fig 5 show that the estimated model is able to describe the relationship between the first and second components of the observed field yielding uncorrelated residual series. Similar analyses were carried out for the rest of PCs and uncorrelated residuals were found.

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