What our ancestors described as worms that gnaw at liver blood can be explained in modern medicine by symptoms remarkably similar to an infection caused by the parasite Clonorchis sinensis. Clonorchis sinensis is a representative foodborne parasite contracted by eating raw freshwater fish in East Asia, including Korea. Once these small flukes enter our body, they travel up the biliary system and settle in the bile ducts inside the liver. The problem is that Clonorchis sinensis chronically irritates biliary epithelial cells and induces inflammation. While it initially begins with mild abdominal pain, dyspepsia, or fatigue, over time the biliary tract wall thickens and fibrosis progresses, which can trigger several serious complications. One of the most common symptoms is jaundice. When Clonorchis sinensis blocks the biliary tract or induces inflammation that obstructs bile drainage, the bile pigment bilirubin accumulates in the bloodstream, resulting in jaundice where the skin and eyes turn yellow. Furthermore, chronic cholangitis can bring about epigastric pain, fever, and chills, and in severe cases, it can lead to cholelithiasis, biliary stricture, and even hepatomegaly. What makes Clonorchis sinensis infection especially dangerous is that prolonged infection greatly increases the risk of developing cholangiocarcinoma, to the extent that the World Health Organization designated Clonorchis sinensis as a group 1 carcinogen. Because cholangiocarcinoma has a notoriously poor prognosis, early diagnosis and treatment of Clonorchis sinensis infection are critical. Diagnosis is primarily made by identifying parasite eggs through a stool examination or detecting antibodies via a blood test, and biliary lesions can also be evaluated through imaging studies such as ultrasound, computed tomography, and magnetic resonance imaging. Treatment can be achieved simply with a single administration of the medication praziquantel; however, if biliary tract damage has already progressed severely, surgery may be necessary. Above all, prevention is paramount: freshwater fish must be thoroughly cooked, and cooking utensils like cutting boards and knives must be strictly managed to prevent cross-contamination. While infection rates have fallen significantly compared to the past, this is precisely why continued vigilance remains necessary.
