Another proof that parasitic worms can infect humans even if they eat primitive "natural" foods and follow primitive habits in nature, and even in europe (no need to live in a tropical country !) :
Ötzi is a human who lived approximately 5200 years ago in the mountains between Austria and Italy.
His mummy was found in ice and he was apparently infected by whipworm (Trichuris trichiura)
See : http://en.wikipedia.org/wiki/%C3%96tzi#Health
Keep in mind that at this time the travels and commerce was local because of the limited technology.
So even if we try to be clean nowadays, there are many more ways to inspire or to ingest parasitic worms eggs coming from all parts of the world with humans, animals, external parasites (mosquitos, taons, spiders, tics, fleas), foods, waste networks, infected surfaces, etc...
Another reason to tell the raw food fanatics and the hygienists to stop their propaganda and to see the reality as it is.