So, it’s a little gross, but I was running late and went straight from my open water swim to work. I managed to shower about 12 hours after I got out of the lake. During that time, the back of my knee began to itch. It’s since turned into a flat, sheet like rash that feels a lot like poison ivy (not quite as intense). I’m in northern Illinois, the lake is private/no motors. My buddy and I did travel through a fair amount of seaweed but the majority of the swim was over blackness.
Since that time some smaller bumps have appeared on other parts of my body (again, similar to how poison ivy ‘pops up’ in new areas). They have not become flat and don’t itch nearly as much.
Yeah, it’s gross. But I was hoping someone has had experience with this before and could tell me if it’s a microorganism or maybe an irritant that is in the water? I’ve been in this lake several times before without any problems. The only difference is the length of exposure (about an hour) and the lack of a shower immediately after.
You also might want to see a dermatologist or Dr on it. I picked up a fungus last year from a lake that had bacteria problems. Sort of reminded me of eczema/poison ivy, but way Dr isolated it is the fungus will glow under a black light. Not really harmful, just annoying, and they prescribed a shampoo I had to wash with to get rid of it.
Ugh. It might be “swimmer’s itch”. Swimmer’s itch is caused by a flatworm that is a parasite that attaches to the skin. Humans have enough immunity to fight it off but it can cause a poison ivy-like rash on the skin that may last for 10 to 14 days. I got it 9 times one summer when doing a bunch of adventure races. It was sooooo annoying. Don’t scratch… It may scar. It might continue to spread. The only relief I got was to put hot or cold water on it. Benedryl topical cream worked a little. Hope you get some relief.
What is the duck population like in the lake? Rocky, muddy or sandy bottom by the shore? If it is Swimmer’s itch you are ok. It is caused by a trematode that normally infects waterfowl (via a snail intermediate host), but will penetrate your skin and die (since you ain’t no duck). Nothing to worry about if this is what it is. You will get some pustules that eventually scab over and it is usually itchy as hell.