When I was a kid my cousins and friends used to swim in a River near our house but that River is not clear and clean anymore so there's a Leeches that possibly lives in that River. And, also I heard a rumors that there is a Leeches in that River, that is why I am afraid to be near in the River. I am afraid of Leeches before and even now because I heard so much about them. But, it is surprising for me to know that the Leeches used for a medical before up until now.
