Guys: Don't have any problems with leeches here so I'm not familiar with what they do. Do they cause infection or are they just unsightly? In medieval times they used leeches for medicinal purposes. Here we have tiny ticks that drop down from above or crawl up your legs like leeches. Mostly unsightly, but deer ticks cause Lime Disease, a very debilitating disease that you must become familiar with if you visit the USA and go out into the field. William