A population-based coprological study of human fascioliasis in a hyperendemic area of the Bolivian Altiplano.

The community of Chijipata Alta, at an altitude of 3850 m, near the southern coast of Lake Titicaca in the northern Altiplano of Bolivia, was surveyed for human fascioliasis. The global prevalence (66.7%) and intensity (eggs per gram of faeces--epg: range: 24-4440; arithmetic mean: 1001; geometric mean: 390) proved to be the highest known in the world by means of coprological techniques. These results suggest the existence of highly hyperendemic subzones among the large human fascioliasis-endemic zone of the Bolivian northern Altiplano. Despite the decrease in prevalence and intensity from children (75.0%, 24-4440 epg) to adults (41.7%, 144-864 epg), our findings show that in an hyperendemic zone adult subjects either maintain the parasites acquired when young or are newly infected as the consequence of inhabiting a zone of high infection risk.