Spatial Ascariasis risk estimation using socioeconomic variables

Abstract

Frequently, disease incidence is mapped as area data, for example, census tracts, districts or states. Spatial disease incidence can be highly heterogeneous inside these areas. Ascariasis is a highly prevalent disease, which is associated with poor sanitation and hygiene. Geostatistics was applied to model spatial distribution of Ascariasis risk and socioeconomic risk events in a poor community in Rio de Janeiro, Brazil. Data were gathered from a coproparasitologic and a domiciliary survey in 1550 children aged 1–9. Ascariasis risk and socioeconomic risk events were spatially estimated using Indicator Kriging. Cokriging models with a Linear Model of Coregionalization incorporating one socioeconomic variable were implemented. If a housewife attended school for less than four years, the non-use of a home water filter, a household density greater than one, and a household income lower than one Brazilian minimum wage increased the risk of Ascariasis. Cokriging improved spatial estimation of Ascariasis risk areas when compared to Indicator Kriging and detected more Ascariasis very-high risk areas than the GIS Overlay method.

Keywords:

• Ascaris lumbricoides
• disease risk maps
• Indicator Geostatistics
• Cokriging
• GIS

Acknowledgments

The authors would like to thank the following Brazilian government institutions for their continuing support: Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro–FAPERJ (processes numbers 151.673/99; 152.247/00); Conselho Nacional de Desenvolvimento Científico e Tecnologico–CNPq (process number 112.417/02-7) and Fundação Universitária José Bonifácio–FUJB (process number 9.204-5).