Epidemiology of human fascioliasis: a review and proposed new classification.

The epidemiological picture of human fascioliasis has changed in recent years. The number of reports of humans infected with Fasciola hepatica has increased significantly since 1980 and several geographical areas have been described as endemic for the disease in humans, with prevalence and intensity ranging from low to very high. High prevalence of fascioliasis in humans does not necessarily occur in areas where fascioliasis is a major veterinary problem. Human fascioliasis can no longer be considered merely as a secondary zoonotic disease but must be considered to be an important human parasitic disease. Accordingly, we present in this article a proposed new classification for the epidemiology of human fascioliasis. The following situations are distinguished: imported cases; autochthonous, isolated, nonconstant cases; hypo-, meso-, hyper-, and holoendemics; epidemics in areas where fascioliasis is endemic in animals but not humans; and epidemics in human endemic areas.