The hookworm is a parasitic nematode worm that lives in the small intestine of its host, which may be a mammal such as a fog, cat, or human. This is a map that shows major areas of the United States that were heavily affected by hookworm during the first two decades of the 20th century. On October 26, 1909 the Rockefeller Sanitary Commission for the Eradication of Hookworm Disease was organized as a result of a gift of $1 million from John D. Rockefeller, Sr. The five-year program was a remarkable success and a great contribution to United States public health, instilling public education, medication, field work and modern government health departments in eleven southern states.