Parasites live anywhere and thrive anywhere as well. They are also found in humans and animals and thus they get food.
Many insects like single-celled organisms or worms make the infections of the parasites much and multiply by millions in the United States.
Humans suffer often from serious diseases of parasites. Parasite diseases are made by protozoa and helminths.
Protozoa are a single-cell organism like any other animal, hunt and collect microbes. Many of them are inside their intestines and the tract and do no harm. Some, on the other hand, make diseases like Giardia and malaria.