Towel off vigorously after swimming and change into clean dry clothes. Avoid swimming at midday when the cercaria (the swimmer’s itch parasite) are most active, and avoid the areas exposed to prolonged onshore winds (the larvae drift near the surface and accumulate in a wind). Other precautions to take include swimming in deeper water where the snails are unlikely to occur, and avoiding feeding waterfowl and attracting them into your swimming area. Their presence will only exacerbate an existing problem. Rubbing on baby oil before swimming has helped in some cases.