When you swim in lakes & rivers, you typically don't get water way up your sinuses. Maybe a bit in the nose but not far back. So the odds are lower. Not impossi

When you swim in lakes & rivers, you typically don't get water way up your sinuses. Maybe a bit in the nose but not far back. So the odds are lower. Not impossible as there have been case of triathletes dying from the same thing after a lake race, but definitely lower odds. As for the ocean, its salinity prevents that kind of amœba from even being present.