I read on some site that one of the reasons is the lack of salt in the diet. Cited examples of how people use to cure meat and things with salt and now don't, people on 'restricted salt intake diets', etc.
Eat More Salt was the motto.
I believe it. parasites hate salt (other than salt-water parasites).
Go find a soft-skinned bug and sprinkle salt on it if you don't believe.
I also think that there are a lot of other things that are encouraging parasites, like making ourselves unhealthy with junk food, sugar, processed foods, eating and drinking out of plastics, polluting our drinking water...the list goes on and on. And stress. Stress alters the body's chemistry and makes us more vulnerable to parasite invasion.