Nonparametric spatial analysis to detect high-risk regions for schistosomiasis in Guichi, China

Zhang, Zhijie; Clark, Allan; Bivand, Roger; Chen, Yue; Carpenter, Tim E.; Peng, Wei‐Xia; Zhou, Yibiao; Jiang, Qingwu

doi:10.1016/j.trstmh.2008.11.012

Cited by 21 publications

(49 citation statements)

References 35 publications

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“…In parallel, other researchers used a nonparametric, spatial model to identify two significant high-risk regions for schistosomiasis by analysing surveillance data for acute schistosomiasis in P.R. China (Zhang et al, 2009c) finding that temporal or/and spatial aggregation with respect to the distribution of snails, parasite eggs and acute human cases.…”

Section: Relationships Between Factors/variablesmentioning

confidence: 99%

Schistosomiasis japonica: Modelling as a tool to explore transmission patterns

Xu¹,

Lv²,

Qingyun³

et al. 2015

Acta Tropica

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Section: Relationships Between Factors/variablesmentioning

confidence: 99%

Schistosomiasis japonica: Modelling as a tool to explore transmission patterns

Xu¹,

Lv²,

Qingyun³

et al. 2015

Acta Tropica

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“…It was used to link the attributed data to establish a spatial database for schistosomiasis (Zhang et al, 2008(Zhang et al, , 2009a. During the 10-year study period, the administrative divisions changed slightly.…”

Section: Base Mapmentioning

confidence: 99%

“…Current endemic regions have been largely confined to the lake and marshland regions in the provinces of Hunan, Hubei, Anhui, Jiangxi and Jiangsu, and the hilly and mountainous regions in the provinces of Yunnan and Sichuan (Utzinger et al, 2005;Zhao et al, 2005;Zhou et al, 2005a). Transmission of schistosomiasis in the plain regions with waterway networks, was interrupted long ago through the snail elimination (Zhang et al, 2009a;Zhou et al, 2010). According to the latest report of the national schistosomiasis control programme, only an estimated 1.3% of the total area remained snail-ridden with 2% of the population infected in Yunnan and Sichuan in 2009 (Hao et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Spatial comparison of areas at risk for schistosomiasis in the hilly and mountainous regions in the People’s Republic of China: evaluation of the long-term effect of the 10-year World Bank Loan Project

Zhang

Zhu

Bergquist³

et al. 2012

Geospat Health

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Abstract. The long-term effectiveness of the mainly chemotherapy-based control strategy of the World Bank Loan Project (WBLP) for schistosomiasis control in Chinese hilly and mountainous regions was evaluated with a view to determine the best road forward. Based on the national database of schistosomiasis prevalence for the periods of 1999-2001 and 2007-2008 in the People's Republic of China, a Bayesian regression model was used for spatial comparison of schistosomiasis risk distribution between two periods taking account of all the potential risk factors simultaneously through two latent components of random effects: spatially correlated heterogeneities (CH) and spatially uncorrelated heterogeneities (UH). Four different types of endemic areas were investigated: those that remained endemic despite control efforts (17 or 37.8%), those that became non-endemic (9 or 20.0%), those that reverted back to endemicity (7 or 15.6%), and those with fluctuating endemicity (12 or 26.7%). The overall prevalence of schistosomiasis was lower in 2007-2008 compared with that in 1999-2001, but the spatial distribution of risk remained similar. Compared to 1999-2001, the magnitude and range of risk even tended to be greater in [2007][2008]. UH showed a fluctuating pattern, while CH increased gradually doubling over the two periods. There was no evidence for long-term effectiveness of the WBLP chemotherapy-based control strategy in this region. Controlling the effect of UH is still the main aspect of current schistosomiasis control strategy for the hilly and mountainous regions, but innovative methods are urgently needed for effectively controlling UH.

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“…Schistosomiasis japonica, a parasitic disease caused by Schistosoma japonicum , has been in existence in the People’s Republic of China (P. R. China) for over 2000 years with considerable public-health and economic significance [1, 2]. A large-scale national schistosomiasis control programme was initiated in the mid-1950s [2, 3], when China’s population was approximately 600 million.…”

Section: Introductionmentioning

confidence: 99%

The basic reproductive ratio of Barbour’s two-host schistosomiasis model with seasonal fluctuations

Gao

Cao

et al. 2017

Parasites Vectors

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BackgroundMotivated by the first mathematical model for schistosomiasis proposed by Macdonald and Barbour’s classical schistosomiasis model tracking the dynamics of infected human population and infected snail hosts in a community, in our previous study, we incorporated seasonal fluctuations into Barbour’s model, but ignored the effect of bovine reservoir host in the transmission of schistosomiasis. Inspired by the findings from our previous work, the model was further improved by integrating two definitive hosts (human and bovine) and seasonal fluctuations, so as to understand the transmission dynamics of schistosomiasis japonica and evaluate the ongoing control measures in Liaonan village, Xingzi County, Jiangxi Province.MethodsThe basic reproductive ratio R 0 and its computation formulae were derived by using the operator theory in functional analysis and the monodromy matrix theory. The mathematical methods for global dynamics of periodic systems were used in order to show that R 0 serves as a threshold value that determines whether there was disease outbreak or not. The parameter fitting and the ratio calculation were performed with surveillance data obtained from the village of Liaonan using numerical simulation. Sensitivity analysis was carried out in order to understand the impact of R 0 on seasonal fluctuations and snail host control. The modified basic reproductive ratios were compared with known results to illustrate the infection risk.ResultsThe Barbour’s two-host model with seasonal fluctuations was proposed. The implicit expression of R 0 for the model was given by the spectral radius of next infection operator. The R 0 s for the model ranged between 1.030 and 1.097 from 2003 to 2010 in the village of Liaonan, Xingzi County, China, with 1.097 recorded as the maximum value in 2005 but declined dramatically afterwards. In addition, we proved that the disease goes into extinction when R 0 is less than one and persists when R 0 is greater than one. Comparisons of the different improved models were also made.ConclusionsBased on the mechanism and characteristics of schistosomiasis transmission, Barbour’s model was improved by considering seasonality. The implicit formula of R 0 for the model and its calculation were given. Theoretical results showed that R 0 gave a sharp threshold that determines whether the disease dies out or not. Simulations concluded that: (i) ignoring seasonality would overestimate the transmission risk of schistosomiasis, and (ii) mollusiciding is an effective control measure to curtail schistosomiasis transmission in Xingzi County when the removal rate of infected snails is small.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-1983-1) contains supplementary material, which is available to authorized users.

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Nonparametric spatial analysis to detect high-risk regions for schistosomiasis in Guichi, China

Cited by 21 publications

References 35 publications

Schistosomiasis japonica: Modelling as a tool to explore transmission patterns

Schistosomiasis japonica: Modelling as a tool to explore transmission patterns

Spatial comparison of areas at risk for schistosomiasis in the hilly and mountainous regions in the People’s Republic of China: evaluation of the long-term effect of the 10-year World Bank Loan Project

The basic reproductive ratio of Barbour’s two-host schistosomiasis model with seasonal fluctuations

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