How you can get a parasite?

There are many types of parasites, for example fleas and bedbugs. However the most fascinating are the helmintic or worms. Poor hygiene can lead to some infestations, for example. Bilharzia (Schistosomiasis) is a very interesting disease which has a life cycle involving man - urine - excrement - water - water snails (Bomphilaria) - water - and man again. It is a very debilitating disease which occurs mostly in third world countries.