Kind of interesting - especially the part about the virus remaining dormant in the horse's body. That's just like people getting chicken pox. The virus remains in the body, sometimes flaring up in a condition called "shingles" - which, along with chicken pox, is a variety of herpes.
Did I mention that I just got over my first case of shingles just a couple weeks ago? As far as I knew for absolutely sure, I never had chicken pox when I was a kid, although most of my friends did. Then when my kids (and grandkids) were quite young, THEY got chicken pox, but I remained unaffected.
The irony of the whole situation is that my doc was going to give me a definitive test to see if that virus was in my system. If it was, he was going to give me a shingles shot. A bit late for running the test now, though. And he recommends getting a shingles vaccination "in about a year".
I can only imagine a horse with "equine shingles". Not pleasant.
I apparently DID have chicken pox in my youth. It may have been misdiagnosed as a variety of measles; I had "red", "German", "black" and "white" measles, according to my oldest charts. But chicken pox is never mentioned.