Veterans returned to the U.S. after fighting in the jungles of Vietnam a half century ago, but hundreds of them may be dying from a silent bullet — a slow-killing parasite living in the men decades after the war, a new study revealed. Liver flukes, parasites that infect a human when raw or undercooked fish is eaten, are being investigated as the cause of a rare bile duct cancer among veterans who served in the Vietnam War. It could take years for symptoms to show up, but when they do, the host is left with tremendous pain and given just...