A large outbreak of Opisthorchis felineus in Italy suggests that opisthorchiasis develops as a febrile eosinophilic syndrome with cholestasis rather than a hepatitis-like syndrome.

We describe the greatest Italian human acute opisthorchiasis outbreak acquired from eating raw tenches. Out of 52 people with suspected opisthorchiasis, 45 resulted in being infected. The most frequent symptoms and laboratory findings were fever, abdominal pain and eosinophilia. Seven tri-phasic computed tomography (CT) scans were done, showing multiple hypodense nodules with hyper-enhancement in the arterial phase. All patients took one day of praziquantel 25 mg/kg TID without failures. Reported symptoms suggested a febrile eosinophilic syndrome with cholestasis rather than a hepatitis-like syndrome. It seems common to find hepatic imaging alterations during acute opisthorchiasis: CT scan could be the most suitable imaging examination. Even if stool test remains the diagnostic gold standard, we found earlier positivity with the serum antibody test. Without previous freezing, the consumption of raw freshwater fish should be avoided.