4. Worms, Worms, Worms!

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It is estimated that roughly half of the entire human population is infected with either hookworms, whipworms or large roundworms. This is due largely to the unsanitary living conditions and lack of safe food supplies in much of the world. As a whole, the human race is a pretty wormy species. And we thought it was bad enough to have to worry about getting our pets wormed!