Well, just how rare can it be when three posters (plus the brother of another one) have contracted the disease more than once?
Or are we dopers some weird brand of human who challenge medical orthodoxy? 
I agree with The Mermaid sorta…it sound like shingles to me…
IANA Nurse, but my mother, 2 aunts and my grandmother are all nurses! ~L~ At any rate, I got the chickenpox when I was a baby, maybe 2 years old.
Since then I’ve had the shingles twice, once when I was about 14 and once about 2 years ago. They usually appear around your waist, though it’s possible to see them appear in other places on your body. The shingles are like a dormant form of chickenpox and are very painful, as she stated.
~J
There are several explanations.
If a person contracted a very mild case of chicken pox at an age of six months or less they would have still been protected by the immunity passed on by their mother. This maternal immunity only lasts a few months. Their immature immune system may not have been able to develop antibodies to the disease, thus they would still be susceptible.
If a person had a very mild case of chicken pox not severe enough to develop sufficent antibodies to provide lifelong immunity they would still be susceptible.
If a person’s immune system is severely compromised by disease, medications, or genetics, they could contract the disease twiceor more.
If a person developed shingles and were told by a physician that shingles is caused by the chicken pox virus, they could mistakenly believe that they have chicken pox again.
If a person developed shingles they could mistake them for chicken pox because the lesions look similar.
A person could have another infection that resembles chicken pox.
Still if a person with a normal immune system contracts a full blown case of chicken pox, the chance of him/her ever developing chicken pox again is very very slight.
I had chicken pox twice, my mom and brother had it twice too. Our doctor told us that if you had a mild case initially (no matter what age) you still can get chicken pox again. Man, the second bout was horrendous. I still have a couple scars.
See explanation #2.
As for the OP. Sorry about getting a little sidetracked arguing about the likelyhood of chicken pox.
After a little thought, scabies comes to mind. Or perhaps some form of excema.
Both my doses of chicken pox were reasonably severe (but luckily without complications). The first at age 15 and then again at age 21 saw me covered all over with the lesions, and feeling bloody crook for a week or more.
Anyway, I always understood that it doesn’t matter HOW severe the initial infection is, that immunity should always be provided. Isn’t that the basis of Immunisation Programs…infect the recipient with a low enough dose of the infective agent so as not to manifest any symptoms, but life-long immunity will still be obtained?
This is what happened to me. I got chicken pox when I was just a few weeks old (still have a very strange-looking scar on my stomach to prove it). Then, when I was four, I caught it from my brother (his case was so mild my parents thought it was just bug bites, so sent him to school and let him play with me, etc), and I caught it bad. Got a scar here and there from that too.