Intestinal parasitic infections and urbanization.

About a third of the population in the cities of developing countries live in slums and shanty towns. By the year 2000 it is estimated that this number will grow to 2200 million, and by 2025 about 57% of the population in developing countries will be in urban areas. The prevalence of infections caused by Entamoeba histolytica and Giardia intestinalis and the prevalence and intensity of Ascaris lumbricoides and Trichuris trichiura infections may increase among the rural populations who are migrating to these urban and suburban settings owing to the favourable conditions for transmission. Urgent consideration should therefore be given to improving sanitation in deprived urban areas and to treating periodically these populations to reduce the worm burden, especially in school-age children.