Wednesday, 12 June 2019

FOSSC: cecarial dermatitis

Bottom line up front: a swarm of microscopic parasitic tadpoles were too dumb to realise I wasn't a duck.

With that out the way, before I explain further I should probably warn that whilst I’ll try not to be overly graphic, this post is probably not for the squeamish; aside from ducks, it involves an aquatic snail parasite and a nasty rash.

So you might want to stop reading now, extend me your sympathies and rest assured that we've got everything under control.

Basically, on a Monday night about three or four weeks ago, as I got ready for bed I noticed something of a rash developing across a significant area of my torso. No fever, no discomfort, it didn’t even itch. So I noted it as something of a curiosity and then proceeded to ignore it. As I tend to do with most injuries or ailments. I'm not in any way suggesting this is responsible behaviour however.

It didn’t go away though, and over the next few days became inflamed and now, some weeks later, is finally healing but is very, very itchy. So much so that I didn’t get much sleep last night. Or the night before.

Across the following weeks I also noticed the same around my lower legs and then again, on a later evening, my left forearm, albeit in this latter case it was only the beginning of a rash, an irregularity of the skin, and didn’t develop further. But this happened on a Wednesday evening after I’d been sailing the Enterprise. 

The Enterprise is a much dryer boat than the Laser; on a gentle day, if goes to plan, the only part of you that gets wet is (yes, you’ve guessed it) your left arm, when you push the rudder down into position after launching.

So the source of this nuisance rash was becoming pretty clear.

It turns out to be cercarial dermatitis. Something more commonly known as “swimmer’s itch”. 

I say “commonly”, but I’d never heard of it before. 

I’d guessed it was something to do with the lake; essentially any areas not covered by my wetsuit have been affected. Which at this time of year is a three-quarter length set of hikers, leaving my lower legs, upper abdomen, torso and arms directly exposed to the water. 

I’d assumed it was something to do with the water chemistry. The water levels are low  (as I’ve moaned about before) the lake is choked with weed (as I’ve moaned about before) and the margins of the lake were buffered with bales of barley straw in the Spring to eliminate the blue-green algae of previous years. If that’s not messing with the chemistry of the water, I don’t know what is.

But no. It’s not chemistry. It’s biology. It turns out it’s a parasitic worm.

Not a parasitic infection, I should hasten to add. I’m just collateral damage, a misfire. Unlike some other parasitic worms, this parasite can’t infest humans.

It infects the blood of waterfowl. Said fowl then excrete eggs, which hatch into larval miracidia which then infest aquatic snails. Of which you’d think there would be a fair few in the lake, given the abundance of vegetation for them to feast on at the moment. The miricidia then develop further in their molluscan hosts until they are excreted as microscopic, tadpole-like larvae called cercariae.

These vicious little beasties live in the water for about 24 hours, during which time they swim around the lake hunting for waterfowl to infect and thus begin the whole happy cycle again. Yep, this is the Circle of Life, in all it’s gritty, itchy, tadpole-like glory.

Unfortunately, their hunting instincts are not all they should be, and if they mistakenly land on a person’s skin, like mine whilst I'm swimming back to my capsized boat (again) they’ll attack and burrow in, presumably thinking you’re some kind of big, pink duck. Or goose. Or something. Let's say a swan. I'd much rather be a swan.

Which is unfortunate for them, as they can’t survive in humans. They die. There is zero risk they'll infest your blood or you'll in anyway harbour, host or pass them on. Unfortunately though, you can develop an allergic reaction to this failed invasion.

Thus this rather uncomfortable rash I’m currently having to endure.

I guess it’s good news that it’s not infectious. And good news that the parasite can’t actually infest humans. I picked up a ringworm infection when I was a kid from a stray kitten a bunch of us kids adopted, and one parasitic worm infection in a lifetime is more than enough for me, thank-you.

Not so good is that there is no way to prevent it happening again, other than to avoid contact with infested waters.

Which would mean not sailing at Frampton. So obviously that’s not going to happen.

So I’m taking daily antihistamines to try and prevent or reduce any future reactions, and the chemist has given me chlorphenamine tablets (a generic, non-branded Piriton equivalent) to take four times a day to deal with the present situation, along with the advice that I can use them again if it reoccurs. And a cream to use twice a day to try and reduce the itching. Which, of course, I’m not allowed to scratch.

But scratching feels sooo good. Why are all the good things always bad for you?

Obviously, not capsizing or otherwise limiting my exposure to the water would help. A drysuit or full wetsuit on the rougher days perhaps, but I do like my hikers when I’m sailing the Laser. And my full wetsuit or the drysuit is a bit too much on a lake during the British summer, quickly becoming something of a boil-in-the-bag situation unless it’s pouring with rain. Which, funny enough, doesn’t actually happen all that much in this country, contrary to any impressions we have have given otherwise.

Apparently, these infestations are more likely to occur on bright, sunny days, and when the water is very clear. Exactly when I don’t want to be wearing a wetsuit. And exactly when you want to be out sailing and enjoying the lake.

I’ll just have to settle for a new pair of waterproof socks to give my legs some protection whilst launching, and try not falling in.

We shall see how it goes. 

Anyway, there is a race this evening, so if you want me, you know where I'll be.

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