There are domestic parasites, and there are some you find mostly in warmer countries.
This is a well known fact that warm/humid countries are more exposed to parasites and contagious diseases than colder ones.
Nothing political here; all contacts with these countries, wether thru immigration or tourism can be a factor in the spreading of parasites, plus global warming which tends to expand the areas where these problems are prevalent.
Just try to go to Mexico or Egypt and drink the water,you will see if there is no difference with the US or Western Europe concerning the risks of parasite infestation.
Each year, tourists die in these countries for underestimating these risks.