Opisthorchis felineus, an emerging infection in Italy and its implication for the European Union

The liver fluke Opisthorchis felineus is one of the few zoonotic trematodes that circulates in the European Union (EU). It is transmitted from freshwater snails to fish and then to fish-eating mammals, including humans, in which it causes opisthorchiasis. In the 20th century, the majority of infections in humans have been reported in Eastern Europe (e.g., Belarus, Russia, and Ukraine) and Asia (Siberia). In EU in the last fifty years, the parasite has been detected in humans of Germany and Greece, and in red foxes, polecats, cats, dogs, fish and mollusks of Germany, Italy, Poland, Portugal and Spain. In Italy, four individual cases and eight outbreaks of opisthorchiasis were reported from 2003 to 2011, for a total of 211 confirmed infections in humans. All infected persons had consumed raw fillets of tench (Tinca tinca) fished from two lakes in central Italy, but some of infected people were tourists who developed the disease in their respective home-countries. In the past decade, it has become increasingly popular to consume raw marinated fillets of fish. The objective of this review is to show how a change in human food habits have caused and increased the transmission of O. felineus, which has probably been circulating in the EU yet in a silent form for many years.