title: Quantitative assessment of geophagous behaviour as a potential source of exposure to geohelminth infection.
abstract: The most common form of pica, geophagy, has direct adverse nutritional effects and also exposes children to soil-borne infection. Existing methods for assessing geophagy are either inappropriate for field use (radiology) or unreliable (reporting). A new method is described, based on the measurement of soil-derived silica in stools. More than 90% of silica is excreted within one gut transit period of ingestion. The amount excreted is proportional to the amount ingested. Faecal levels of dietary silica (less than 2% dry wt stool) can be distinguished from levels due to geophagy (up to 25% dry wt stool). Studies in 2 children's homes in Jamaica showed that 33% and 66% of children were geophagous, ingesting up to 10 g soil day-1. The geophagy of less than 20% of the children accounted for greater than 60% of the total soil ingested. This overdispersion of exposure to soil-borne infection may contribute to the observed aggregation of geohelminth infection.
authors.affiliation: Department of Zoology, University of the West Indies, Kingston, Jamaica.
authors.forename: M S
authors.initials: MS
authors.lastname: Wong
authors.forename: D A
authors.initials: DA
authors.lastname: Bundy
authors.forename: M H
authors.initials: MH
authors.lastname: Golden
mesh_terms: D002648:Child; D002675:Child, Preschool; D005243:Feces / Q000032:analysis; D006373:Helminthiasis / Q000635:transmission*; D006801:Humans; D008722:Methods; D010842:Pica / Q000150:complications / Q000453:epidemiology*; D012822:Silicon Dioxide / Q000032:analysis; D012987:Soil; D013997:Time Factors
chemical_list: D012987:Soil; D012822:Silicon Dioxide