Spatio-temporal distribution of soil-transmitted helminth infections in Brazil

Particle and Fibre Toxicology

Penelope Vounatsou⁴  Jürg Utzinger⁴  Mara E Bavia¹  Ronaldo GC Scholte²  Luiz H Guimarães³  Frédérique Chammartin⁴ 

[1] Preventive Medicine Department, Federal University of Bahia, Salvador 40110-060, Bahia, Brazil;Coordenação Geral de Hanseníase e Doenças em Eliminação, Secretaria de Vigilância em Saúde, Brasília 70304-000, Distrito Federal, Brazil;Immunology Service, Hospital Edgard Santos, Federal University of Bahia, Salvador 40110-160, Bahia, Brazil;University of Basel, P.O. Box, CH-4003 Basel, Switzerland

关键词: Brazil;    Spatio-temporal model;    Bayesian geostatistics;    Predictive risk mapping;    Trichuris trichiura;    Hookworm;    Ascaris lumbricoides;    Soil-transmitted helminth;   

Others  :  1150227
DOI  :  10.1186/1756-3305-7-440

 received in 2014-04-30, accepted in 2014-09-13,  发布年份 2014

【 摘 要 】

Background

In Brazil, preventive chemotherapy targeting soil-transmitted helminthiasis is being scaled-up. Hence, spatially explicit estimates of infection risks providing information about the current situation are needed to guide interventions. Available high-resolution national model-based estimates either rely on analyses of data restricted to a given period of time, or on historical data collected over a longer period. While efforts have been made to take into account the spatial structure of the data in the modelling approach, little emphasis has been placed on the temporal dimension.

Methods

We extracted georeferenced survey data on the prevalence of infection with soil-transmitted helminths (i.e. Ascaris lumbricoides, hookworm and Trichuris trichiura) in Brazil from the Global Neglected Tropical Diseases (GNTD) database. Selection of the most important predictors of infection risk was carried out using a Bayesian geostatistical approach and temporal models that address non-linearity and correlation of the explanatory variables. The spatial process was estimated through a predictive process approximation. Spatio-temporal models were built on the selected predictors with integrated nested Laplace approximation using stochastic partial differential equations.

Results

Our models revealed that, over the past 20 years, the risk of soil-transmitted helminth infection has decreased in Brazil, mainly because of the reduction of A. lumbricoides and hookworm infections. From 2010 onwards, we estimate that the infection prevalences with A. lumbricoides, hookworm and T. trichiura are 3.6%, 1.7% and 1.4%, respectively. We also provide a map highlighting municipalities in need of preventive chemotherapy, based on a predicted soil-transmitted helminth infection risk in excess of 20%. The need for treatments in the school-aged population at the municipality level was estimated at 1.8 million doses of anthelminthic tablets per year.

Conclusions

The analysis of the spatio-temporal aspect of the risk of infection with soil-transmitted helminths contributes to a better understanding of the evolution of risk over time. Risk estimates provide the soil-transmitted helminthiasis control programme in Brazil with useful benchmark information for prioritising and improving spatial and temporal targeting of interventions.

【 授权许可】

   
2014 Chammartin et al.; licensee BioMed Central Ltd.

【 图 表 】

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