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Bayesian geostatistical modelling for mapping schistosomiasis transmission

  • P. VOUNATSOU (a1), G. RASO (a2) (a3), M. TANNER (a1), E. K. N'GORAN (a4) (a5) and J. UTZINGER (a1)...

Progress has been made in mapping and predicting the risk of schistosomiasis using Bayesian geostatistical inference. Applications primarily focused on risk profiling of prevalence rather than infection intensity, although the latter is particularly important for morbidity control. In this review, the underlying assumptions used in a study mapping Schistosoma mansoni infection intensity in East Africa are examined. We argue that the assumption of stationarity needs to be relaxed, and that the negative binomial assumption might result in misleading inference because of a high number of excess zeros (individuals without an infection). We developed a Bayesian geostatistical zero-inflated (ZI) regression model that assumes a non-stationary spatial process. Our model is validated with a high-quality georeferenced database from western Côte d'Ivoire, consisting of demographic, environmental, parasitological and socio-economic data. Nearly 40% of the 3818 participating schoolchildren were infected with S. mansoni, and the mean egg count among infected children was 162 eggs per gram of stool (EPG), ranging between 24 and 6768 EPG. Compared to a negative binomial and ZI Poisson and negative binomial models, the Bayesian non-stationary ZI negative binomial model showed a better fit to the data. We conclude that geostatistical ZI models produce more accurate maps of helminth infection intensity than the spatial negative binomial ones.

Corresponding author
*Corresponding author: Penelope Vounatsou, Department of Public Health and Epidemiology, Swiss Tropical Institute, P.O. Box, CH-4002 Basel, Switzerland. Tel: +41 61 284-8109. Fax: +41 61 284-8105. E-mail:
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D. K. Agarwal , A. E. Gelfand and S. Citron-Pousty (2002). Zero-inflated models with application to spatial count data. Environmental and Ecological Statistics 9, 341355.

R. M. Anderson and R. M. May (1985). Helminth infections of humans: mathematical models, population dynamics and control. Advances in Parasitology 24, 1101.

S. Banerjee , A. E. Gelfand , J. R. Knight and C. F. Sirmans (2004). Spatial modeling of house prices using normalized distance-weighted sums of stationary processes. Journal of Business and Economic Statistics 22, 206213.

R. Bergquist , M. V. Johansen and J. Utzinger (2009). Diagnostic dilemmas in helminthology: what tools to use and when? Trends in Parasitology 25, 151156.

M. Booth , B. J. Vennervald , L. Kenty , A. E. Butterworth , H. C. Kariuki , H. Kadzo , E. Ireri , C. Amaganga , G. Kimani , J. K. Mwatha , A. Otedo , J. H. Ouma , E. Muchiri and D. W. Dunne (2004). Micro-geographical variation in exposure to Schistosoma mansoni and malaria, and exacerbation of splenomegaly in Kenyan school-aged children. BMC Infectious Diseases 4, 13.

D. J. Bradley (1972). Regulation of parasite populations. A general theory of the epidemiology and control of parasitic infections. Transactions of the Royal Society of Tropical Medicine and Hygiene 66, 697708.

S. Brooker (2007). Spatial epidemiology of human schistosomiasis in Africa: risk models, transmission dynamics and control. Transactions of the Royal Society of Tropical Medicine and Hygiene 101, 18.

S. Brooker , N. Alexander , S. Geiger , R. A. Moyeed , J. Stander , F. Fleming , P. J. Hotez , R. Correa-Oliveira and J. Bethony (2006). Contrasting patterns in the small-scale heterogeneity of human helminth infections in urban and rural environments in Brazil. International Journal for Parasitology 36, 11431151.

S. Brooker and A. C. A. Clements (2009). Spatial heterogeneity of parasite co-infection: determinants and geostatistical prediction at regional scales. International Journal for Parasitology 39, 591597.

S. Brooker , N. B. Kabatereine , F. Fleming and N. Devlin (2008). Cost and cost-effectiveness of nationwide school-based helminth control in Uganda: intra-country variation and effects of scaling-up. Health Policy and Planning 23, 2435.

S. Brooker , M. Rowlands , L. Haller , L. Savioli and D. A. P. Bundy (2000). Towards an atlas of human helminth infection in sub-Saharan Africa: the use of geographical information systems (GIS). Parasitology Today 16, 303307.

S. Brooker and J. Utzinger (2007). Integrated disease mapping in a polyparasitic world. Geospatial Health 1, 141146.

A. C. Cameron and P. K. Trivedi (1986). Econometric models based on count data: comparisons and applications of some estimators. Journal of Applied Economics 1, 2953.

A. C. A. Clements , S. Brooker , U. Nyandindi , A. Fenwick and L. Blair (2008). Bayesian spatial analysis of a national urinary schistosomiasis questionnaire to assist geographic targeting of schistosomiasis control in Tanzania, East Africa. International Journal for Parasitology 38, 401415.

A. C. A. Clements , N. J. S. Lwambo , L. Blair , U. Nyandindi , G. Kaatano , S. Kinung'hi , J. P. Webster , A. Fenwick and S. Brooker (2006 a). Bayesian spatial analysis and disease mapping: tools to enhance planning and implementation of a schistosomiasis control programme in Tanzania. Tropical Medicine and International Health 11, 490503.

J. E. Cohen (1977). Mathematical models of schistosomiasis. Annual Review of Ecology and Systematics 8, 209233.

S. J. de Vlas and B. Gryseels (1992). Underestimation of Schistosoma mansoni prevalences. Parasitology Today 8, 274277.

P. J. Diggle , R. A. Moyeed and J. A. Tawn (1998). Model-based geostatistics. Journal of the Royal Statistical Society. Series C, Applied Statistics 47, 299326.

I. Dimatteo , C. R. Genovese and R. E. Kass (2001). Bayesian curve-fitting with free-knot splines. Biometrika 88, 10551071.

A. E. Gelfand and A. F. M. Smith (1990). Sampling based approaches to calculating marginal densities. Journal of the American Statistical Association 85, 398409.

A. Gemperli , P. Vounatsou , I. Kleinschmidt , M. Bagayoko , C. Lengeler and T. Smith (2004). Spatial patterns of infant mortality in Mali; the effect of malaria endemicity. American Journal of Epidemiology 159, 6472.

L. Gosoniu , P. Vounatsou , N. Sogoba and T. Smith (2006). Bayesian modelling of geostatistical malaria risk data. Geospatial Health 1, 127139.

D. Heilbron (1994). Zero-altered and other regression models for count data with added zeros. Biometrical Journal 36, 531547.

U. Kitron , J. A. Clennon , M. C. Cecere , R. E. Gürtler , C. H. King and G. Vazquez-Prokopec (2006). Upscale or downscale: applications of fine scale remotely sensed data to Chagas disease in Argentina and schistosomiasis in Kenya. Geospatial Health 1, 4958.

D. Lambert (1992). Zero-inflated Poisson regression with an application to defects in manufacturing. Technometrics 34, 114.

Y. S. Li , G. Raso , Z. Y. Zhao , Y. K. He , M. K. Ellis and D. P. McManus (2007). Large water management projects and schistosomiasis control, Dongting Lake region, China. Emerging Infectious Diseases 13, 973979.

D. J. Lunn , A. Thomas , N. Best and D. Spiegelhalter (2000). WinBUGS – a Bayesian modelling framework: concepts, structure, and extensibility. Statistics and Computing 10, 325337.

A. Majumdar and A. E. Gelfand (2007). Multivariate spatial modeling for geostatistical data using convolved covariance functions. Mathematical Geology 39, 225245.

J. Mullahy (1986). Specification and testing of some modified count data models. Journal of Econometrics 33, 341365.

G. Raso , A. Luginbühl , C. A. Adjoua , N. T. Tian-Bi , K. D. Silué , B. Matthys , P. Vounatsou , Y. Wang , M. E. Dumas , E. Holmes , B. H. Singer , M. Tanner , E. K. N'Goran and J. Utzinger (2004). Multiple parasite infections and their relationship to self-reported morbidity in a community of rural Côte d'Ivoire. International Journal of Epidemiology 33, 10921102.

G. Raso , P. Vounatsou , L. Gosoniou , M. Tanner , E. K. N'Goran and J. Utzinger (2006 b). Risk factors and spatial patterns of hookworm infection among schoolchildren in a rural area of western Côte d'Ivoire. International Journal for Parasitology 36, 201210.

G. Raso , P. Vounatsou , D. P. McManus and J. Utzinger (2007). Bayesian risk maps for Schistosoma mansoni and hookworm mono-infections in a setting where both parasites co-exist. Geospatial Health 2, 8596.

G. Raso , P. Vounatsou , B. H. Singer , E. K. N'Goran , M. Tanner and J. Utzinger (2006 a). An integrated approach for risk profiling and spatial prediction of Schistosoma mansoni-hookworm coinfection. Proceedings of the National Academy of Sciences, USA 103, 69346939.

J. Rodrigues (2003). Bayesian analysis of zero-inflated distributions. Communication in Statistics-Theory and Methods 32, 281289.

J. T. Scott , M. Diakhaté , K. Vereecken , A. Fall , M. Diop , A. Ly , D. De Clercq , S. J. de Vlas , D. Berkvens , L. Kestens and B. Gryseels (2003). Human water contacts patterns in Schistosoma mansoni epidemic foci in northern Senegal change according to age, sex and place of residence, but are not related to intensity of infection. Tropical Medicine and International Health 8, 100108.

K. D. Silué , G. Raso , A. Yapi , P. Vounatsou , M. Tanner , E. K. N'Goran and J. Utzinger (2008). Spatially-explicit risk profiling of Plasmodium falciparum infections at a small scale: a geostatistical modelling approach. Malaria Journal 7, 111.

N. Sogoba , P. Vounatsou , M. M. Bagayoko , S. Doumbia , G. Dolo , L. Gosoniu , S. F. Traoré , Y. T. Touré and T. Smith (2007). The spatial distribution of Anopheles gambiae sensu stricto and An. arabiensis (Diptera: Culicidae) in Mali. Geospatial Health 1, 213222.

P. Steinmann , J. Keiser , R. Bos , M. Tanner and J. Utzinger (2006). Schistosomiasis and water resources development: systematic review, meta-analysis, and estimates of people at risk. Lancet Infectious Diseases 6, 411425.

A. S. Stensgaard , A. Jørgensen , N. B. Kabatereine , C. Rahbek and T. K. Kristensen (2006). Modeling freshwater snail habitat suitability and areas of potential snail-borne disease transmission in Uganda. Geospatial Health 1, 93104.

R. W. Sutherst (2004). Global change and human vulnerability to vector-borne diseases. Clinical Microbiology Reviews 17, 136173.

J. Utzinger and D. de Savigny (2006). Control of neglected tropical diseases: integrated chemotherapy and beyond. PLoS Medicine 3, e112.

J. Utzinger , P. Vounatsou , E. K. N'Goran , M. Tanner and M. Booth (2002). Reduction in the prevalence and intensity of hookworm infections after praziquantel treatment for schistosomiasis infection. International Journal for Parasitology 32, 759765.

G. J. Yang , P. Vounatsou , X. N. Zhou , M. Tanner and J. Utzinger (2005 a). A Bayesian-based approach for spatio-temporal modeling of county level Schistosoma japonicum prevalence data in Jiangsu province, China. International Journal for Parasitology 35, 155162.

Y. G. Yapi , O. J. T. Briët , S. Diabate , P. Vounatsou , E. Akodo , M. Tanner and T. Teuscher (2005). Rice irrigation and schistosomiasis in savannah and forest areas of Côte d'Ivoire. Acta Tropica 93, 201211.

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