@pleonasm - Actually it's the liver fluke known as the "Chinese liver fluke" that's the worst human liver fluke in terms of numbers.
They think it might be infecting around 30 million people, particularly in China and Japan. When you think about the traditional diets of people in those areas, you can see why they'd be vulnerable to a parasite transmitted through fish.
It's not really that deadly, but it lives off bile, which means it can severely affect digestion.
And over time it can definitely weaken someone so that they might be killed by a secondary infection.
It's most definitely not a pleasant disease.