one-quarter of the world’s population is infected with a gut parasite of some kind. Humans evolved with parasitic worms, which have driven genetic diversity in people more than climate, diet, bacteria, or viruses.Today, tapeworm infections remain relatively common, but industrialized countries have relatively low rates of gastrointestinal parasites overall, thanks to a shift to working in more sanitized conditions and away from the land.However, in rural populations with more traditional lifestyles, intestinal parasites remain a part of daily life.