I was told by a friend today that 80 percent of adults live with parasites like worms. i can't stop thinking about this. is that stat true? should i be concerned? if true, what can i do? thank you?

The statement about prevalence of parasite in 80% of people is not true for USA. It is possible in other parts of the world, however it is important to be aware of how parasites could be acquired so you could take precautions rather than be anxious. There are many parasites and could lodge in different organs. They could be acquired various ways; but worms usually are by food contamination.