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Chile is located in the south-werstern border of South America. It is divided into five different ecological zones: deserts, steppes, bushes, forests (cattle raising) and austral (sheep raising). Population: 13,348,401 (16.5% rural).

Human hydatidosis is endemic; about 320 cases are registered each year.

To find out the prevalence of hydatidosis in Chile, a series of serosurveys was conducted in 1988-1997 throughout the country. By using the indirect hemagglutination test and ELISA for hydatidosis 60,490 unselected apparently healthy people from urban (41,399) and rural (19,091) sections were studied.

A total of 82 (136/100,000) resulted positive: 36 (87/100,000) urban and 46 (241/100,000) rural, being the prevalence higher in rural sections, particularly in the austral zone. These figures agree with those observed in clinical epidemiological studies. According to these results, in the whole country 16,209 persons should have hydatidosis: 8,939 urban and 7,269 rural. All these possible infected people, potentially future clinical cases, not necessarily should present pathology, as it has been observed in autopsies from unselected individuals, performed at the Medico-Legal Service in Santiago, in whom 71.3% of diagnosed hydatidosis, was an autopsy finding.