This is an illness suffered by people who drink milk from cows that have grazed on a plant known as white snakeroot. Milk sickness was a frequent cause of illness and death in the Midwest and rural South during the nineteenth century, sometimes killing as many as half the people in a particular settlement. There are estimates that 10 to 25 percent of those afflicted died. Nancy Hanks Lincoln, Abraham Lincoln's mother, died from milk sickness in Indiana.
White snakeroot grows abundantly in Minnesota and in other states in the Midwest.
It is not usually found in pastures but grows well in or near woods. Even sheep and hogs are poisoned by white snakeroot. If cows graze on this plant they will become sick and the milk will still be toxic to people. In the past, however, farmers and rural people drank milk from local herds. Today, milk is collected from many farms and bulked so that any toxin present is diluted below the toxic concentration.