Fifty years after serving in the United States military, hundreds of Americans have a reason to believe they may be dying from a silent killer. Test results show some of the men may have been infected by a parasite while fighting in Southeast Asia. Earlier this year, the U.S. Department of Veterans Affairs (VA) ordered a small study of military veterans. The department wanted to investigate a possible link between a rare form of bile duct cancer and parasitic worms called liver fluke. The small organisms can enter the body when someone eats raw or uncooked fish. Many years can pass before signs of infection appear. By then, those who have been infected are often in severe pain, and have just a few months to live.