Risk factors for Echinococcus granulosus infection: a case-control study.

Despite the importance of cystic hydatid disease worldwide, no case-control study evaluating the risk factors for Echinococcus granulosus infection has been published to date. Thus, we carried out a hospital study to quantify different risk factors associated with the disease in a province marked by a high incidence of hydatidosis (Soria, Spain). The study population was composed of 127 cases and 127 controls matched by sex, age, and residence. Odds ratios (ORs) for hydatidosis decreased inversely with size of place of birth and residence, and increased with the number of dogs and years of coexistence with them. The variable involving the possibility of dogs ingesting uncooked viscera or carrion proved to be of greater importance (OR = 3.99, 95% confidence interval = 1.94-8.20). Risk factors for hydatidosis traceable to the family environment are of greater relative importance than those attributable to working directly with livestock. No association could be found between ingestion of raw green vegetables and hydatidosis.