> ...victims succumbed to an insatiable exhaustion and an impenetrable haziness of the mind that some called stupidity. Adults neglected their fields and children grew pale and listless. Victims developed grossly distended bellies and “angel wings”—emaciated shoulder blades accentuated by hunching. All gazed out dully from sunken sockets with a telltale “fish-eye” stare.

https://www.pbs.org/wgbh/nova/article/how-a-worm-gave-the-so...

> In 1899, American zoologist Charles Wardell Stiles identified progressive pernicious anemia seen in the southern United States as being caused by the hookworm A. duodenale. Testing in the 1900s revealed very heavy infestations in school-age children.

> On October 26, 1909 the Rockefeller Sanitary Commission for the Eradication of Hookworm Disease was organized as a result of a gift of US$1 million from John D. Rockefeller, Sr. The five-year program was a remarkable success and a great contribution to the United States' public health, instilling public education, medication, field work and modern government health departments in eleven southern states.[45] The hookworm exhibit was a prominent part of the 1910 Mississippi state fair.

> The commission found that an average of 40% of school-aged children were infected with hookworm.

https://en.wikipedia.org/wiki/Hookworm_infection#Eradication...