COMMON-SOURCE OUTBREAK OF ACUTE INFECTION DUE TO THE NORTH-AMERICAN LIVER FLUKE METORCHIS-CONJUNCTUS

Background We investigated an outbreak of acute clinical illness among 19 people who ate raw fish (sashimi) prepared from the white sucker, Catostomus commersoni, caught in a river north of Montreal, Canada. Me thods We collected epidemiological, clinical, laboratory, and serologi cal data on 19 individuals who ate the sashimi and six who did not. Be cause of the suggestive clinical picture, we set out to recover helmin th parasites from uneaten fish. Findings The illness consisted of pers istent upper abdominal pain, low grade fever, high blood eosinophil co ncentrations, and raised liver enzymes. After 10 days, opisthorchiid-l ike eggs were found in stools. Symptoms persisted for 3 days to 4 week s without treatment, but responded rapidly to praziquantel therapy. Ne cropsy of golden hamsters infected with metacercariae from uneaten fis h revealed adult flukes identified as Metorchis conjunctus. Interpreta tion We describe an acute illness caused by the North American liver f luke M conjunctus. This is a new human disease and is the first report of a common-source outbreak of an acute illness caused by liver fluke s of the family Opisthorchiidae.