Medical Can sunlight trigger urushiol rash recurrence after a year?

[Echo 6 Sierra]

How would/could direct sunlight cause a reocurrence of an urushiol-type rash almost a year after first notice? Does it attach to certain types of cells and remain in the lymphatic system permanently?

 

[SW VandeCarr]

How would/could direct sunlight cause a reocurrence of an urushiol-type rash almost a year after first notice? Does it attach to certain types of cells and remain in the lymphatic system permanently?

Urushiol is found in plants, particularly toxicodendrons (poison ivy, oak and sumac) and it is the active factor in eliciting an autoimmune response when these plants come into contact with the skin. Urushiol is a pentadecyl catechol which alters certain skin proteins. This sets off a T cell mediated autoimmune (self allergic) response.

I'm not aware that sunlight alone can reactivate this response in cases of a prior exposure. However T cells can carry immune memory which may enhance the reaction to subsequent exposure. There may be possible cross over memory for other related allergens, but I haven't found anything specific on this in a brief search.

So I think it's more likely that if this rash is itchy, it could be a mild reactivation based on a recent unrecognized exposure.

EDIT: In terms of how long immune memory lasts, it's somewhat of an open question depending on the allergen, but without treatment, it often can be many years to a lifetime. For these common types of allergens, most people just live with them. Wear long pants and long sleeve shirts when walking in the woods in the warm seasons (or sit back on the porch look at the view in comfort).

 

[Proton Soup]

you could get exposed to the oil from a pet, or from something you've had in storage like tools or a pair of hiking boots or gloves.

also, be aware that new growth looks very different for poison ivy than old growth. it's often reddish and small. old growth is highly variable, too.

 

[hypatia]

I have never known,nor have I ever heard, anyone to have reoccurring poison ivy rash, without being re-exposed to it again.

 

[hypatia]

I have never known,nor have I ever heard, anyone to have reoccurring poison ivy rash, without being re-exposed to it again.

 

[Echo 6 Sierra]

I've never thought that it could reappear either which is why I posted my question about its longevity and photo-induced reoccurrence. When I returned from helping build the cob house the shirts I wore were thrown away along with all the tenugui I used for sweat bands that week because I know that urushiol is bad juju and is extremely hard to get rid of. I originally used an OTC scrub/paste that stopped the itching in less than a minute. I can only guess that from the pattern it is appearing in now and again that I missed the periphery of the original contamination. Still, its weird how the sun makes it itchy.

Thank you all for the replies. Now to find a dermatologist.

 

[SW VandeCarr]

I originally used an OTC scrub/paste that stopped the itching in less than a minute. I can only guess that from the pattern it is appearing in now and again that I missed the periphery of the original contamination. Still, its weird how the sun makes it itchy.

Thank you all for the replies. Now to find a dermatologist.

Dealing with the area of contact, as a preventative measure, is only useful if you do it right way. If you suspect you've been exposed, wash down the area thoroughly with fresh water ASAP without rubbing or scrubbing. That only drives the urushiol into the skin. Let the area air dry.

 

[Proton Soup]

Dealing with the area of contact, as a preventative measure, is only useful if you do it right way. If you suspect you've been exposed, wash down the area thoroughly with fresh water ASAP without rubbing or scrubbing. That only drives the urushiol into the skin. Let the area air dry.

you don't use soap or detergent to remove the oil?

as for OTC remedies, I've never found anything that works. the Tecnu tuff is just a waterless cleaner (based on mineral oil to dissolve it , iirc). and the products like calamine only treat the symptoms. in any case, i never seem to have it last more or less than 2 weeks, then it's gone. i assume this is simply a matter of how long it takes new skin cells to form and push any antigen up to the surface and shed with dead cells.

 

[SW VandeCarr]

you don't use soap or detergent to remove the oil?

There doesn't seem to be any agreement on the exact steps to take immediately after exposure except to thoroughly rise the area with water. I've seen some recommendations for rubbing alcohol, some for soap, some to avoid soap, etc. It's not clear to what extent these recommendations are evidence based. The first dictum: do no harm.

http://www.associatedcontent.com/article/256894/the_best_immediate_poison_ivy_treatment.html

 

[Proton Soup]

There doesn't seem to be any agreement on the exact steps to take immediately after exposure except to thoroughly rise the area with water. I've seen some recommendations for rubbing alcohol, some for soap, some to avoid soap, etc. It's not clear to what extent these recommendations are evidence based. The first dictum: do no harm.

http://www.associatedcontent.com/article/256894/the_best_immediate_poison_ivy_treatment.html

i guess i will take my chances. water solubility is very low, so it seems unlikely to be helpful at removing any contaminant.
http://en.wikipedia.org/wiki/Urushiol#Characteristics

 

[Echo 6 Sierra]

I used the walgreens generic version of Zanfel. Almost $30.00 for a tube the size of my index finger. This stuff is a miracle drug as far as I'm concerned and worth every penny. Squeeze a small bit on your hand, dampen, make a paste, scrub the infected area until the itching stops which will not be long, rinse. My itching stopped almost immediately and the next day the rash was gone save a few tiny blisters.

 

[Proton Soup]

hmm, apparently zanfel is this?
http://www.google.com/patents/about?id=nvWDAAAAEBAJ&dq=20020183284

 

[hypatia]

Zanfel is worth every penny you pay for it. It makes you feel so good the scratch the itch.