Table 1.

Examples of trematode species of medical importance (data obtained from references [7,22,23,24]).

	Source of Infection	Target Host Organ	Symptoms and Disease Associated with Infection	Geographical Distribution
Foodborne trematodes
Clonorchis sinensis	Ingesting freshwater fish	Bile ducts	Acute: malaise, weakness, anorexia, flatulence, nausea, vomiting, abdominal pain, and diarrhoea Chronic: cholelithiasis, cholestasis, cholangitis, cholecystitis, biliary and liver abscesses, cirrhosis, pancreatitis, hepatitis, cholangiocarcinoma	China, Korea, Russia, Taiwan, Vietnam
Fasciola hepatica	Ingesting semi-aquatic vegetation, contaminated water or infected raw liver	Bile ducts	Acute: fever, abdominal pain, anorexia, flatulence, nausea, diarrhoea, urticaria, and coughing Chronic: cholelithiasis, jaundice, epigastric pain, nausea, fatty food intolerance, cholangitis, pancreatitis, cholecystitis	Worldwide (associated with the distribution of parasitised livestock)
Opisthorchis viverrini	Ingesting freshwater fish	Bile ducts	Acute: malaise, weakness, anorexia, flatulence, nausea, vomiting, abdominal pain, and diarrhoea Chronic: pyogenic cholangitis, biliary calculi, cholecystitis, cirrhosis of the liver, pancreatitis, and cholangiocarcinoma	Cambodia, Laos, Malaysia, Myanmar, Thailand, Vietnam
Paragonimus westermani	Ingesting crabs, crayfish or wild boar meat	Pulmonary tissue	Acute: cough, fever, bloody sputum, loss of appetite, chest pain, headache Chronic: consistent cough with brownish sputum, chest pain, night sweats	Cambodia, China, India, Japan, Korea, Laos, Malaysia, Nepal, Pakistan, Papua New Guinea, The Philippines, Southeast Siberia, Sri Lanka, Taiwan, Thailand, USA, Vietnam
Fasciolopsis buski	Ingesting semi-aquatic vegetation	Small intestine	Acute: diarrhoea, constipation, headache, flatulence, poor appetite, vomiting, abdominal pain, fever Chronic: oedema, anaemia, anorexia, vomiting, gastric pain, pallor, malnutrition, abdominal pain, nausea, bitemporal headache	Bangladesh, Cambodia, China, India, Indonesia, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Pakistan, Singapore, Taiwan, Thailand, The Philippines, Vietnam
Blood flukes
Schistosoma mansoni	Contact with infested water	Mesenteric veins	Acute: myalgia, abdominal pain in the right upper quadrant, diarrhoea, fatigue, malaise, fever Chronic: intestinal disease, hepatosplenomegaly	Brazil, Burkina Faso, Burundi, Cameroon, Chad, Congo, Ivory Coast, Egypt, Ethiopia, Gambia, Ghana, Guinea, Kenya, Liberia, Madagascar, Malawi, Mali, Mauritania, Mozambique, Namibia, Nigeria, Oman, Puerto Rico, Rwanda, Saudi Arabia, Senegal, Sierra Leone, South Africa, Sudan, Suriname, Tanzania, Togo, Venezuela, Uganda, Yemen, Zambia, Zimbabwe
Schistosoma japonicum	Contact with infested water	Mesenteric veins	Acute: myalgia, abdominal pain in the right upper quadrant, diarrhoea, fatigue, malaise, fever Chronic: intestinal disease, hepatosplenomegaly	China, Indonesia, Taiwan, The Philippines
Schistosoma haematobium	Contact with infested water	Venous plexous of the bladder	Acute: myalgia, abdominal pain in the right upper quadrant, diarrhoea, fatigue, malaise, fever, haematuria Chronic: bladder pathology, cancer (squamous cell carcinoma, bladder cancer, vaginal cancer)	Angola, Burundi, Burkina Faso, Cameroon, Central Africa, Chad, Congo, Ivory Coast, Egypt, Ethiopia, Gabon, Ghana, Iran, Iraq, Kenya, Lebanon, Madagascar, Malagasy, Mauritius, Morocco, Mozambique, Namibia, Nigeria, Northern Syria, Réunion, Rwanda, Saudi Arabia, Senegal, Sudan, Tanzania, Togo, Uganda, Yemen, Zambia, Zimbabwe
Schistosoma mekongi	Contact with infested water	Mesenteric veins	Acute: myalgia, abdominal pain in the right upper quadrant, diarrhoea, fatigue, malaise, fever Chronic: intestinal disease, hepatosplenomegaly	Cambodia, Laos