Fasciola hepatica in a country of low incidence: a tricky diagnosis.

Background: Fasciola hepatica is a foodborne trematode present worldwide. Definitive hosts are mostly ruminants such as cattle and sheep, as well as humans. In Switzerland, Fasciola infection in humans is rare. Unfortunately, many patients are likely to undergo multiple unnecessary investigations before the parasite is suspected and fascioliasis diagnosed, especially if symptoms are unspecific.

Methods: Retrospective analysis of all patients diagnosed with Fasciola hepatica at the University Hospital of Bern between 2005 and 2018. Diagnosis was positive if a positive serology and/or eggs in stool samples correlated with clinical presentation (symptoms and/or imaging). Patients were excluded if serology was weakly positive and another diagnosis more likely. Personal data, laboratory results, imaging, proposed treatment and outcome were collected from patient files.

Results: Sixty patients had a positive serology during this time period. Forty-seven of them had a more plausible alternative diagnosis and were not included in the study, leaving 13 patients for analyses; 46.2% (6/13) were male, mean age was 45.8 years old (range, 17-80 years old). Four patients (4/13, 30.8%) were asymptomatic, nine (9/13, 69.2%) presented with symptoms ranging from right upper quadrant abdominal pain (44.4%) and generalized pruritus (33.3%) to weight loss and night sweats (33.3%). The mean duration of symptoms until correct diagnosis was 8.9 months (range, 1-48 months). Five patients (5/13, 38.5%) had documented eosinophilia, four (4/13, 30.8%) elevated liver enzymes and seven (7/13, 53.8%) elevated cholestasis parameters. Mean antibody level on serology was 88 AU/mL (range, 3-134 AU/mL). Ultrasound was used most frequently (7/13, 53.8%), followed by magnetic resonance imaging (4/13, 30.8%), computed tomography and endoscopic retrograde cholangiopancreatography (3/13, 23.1%). The most common findings were bile duct dilatation, followed by hepatic lesions. Treatment consisted of Triclabendazole 10 mg/Kg. One patient needed a second treatment course for persistent disease. There were no recurrences.

Conclusions: With a low incidence of Fasciola hepatica in Switzerland, correct diagnosis is often substantially delayed. Raising awareness among Swiss physicians is paramount, and a higher level of suspicion necessary when confronted with unspecific symptoms or liver imaging, thus avoiding a long delay in diagnosis, as well as unnecessary tests.