In the internet sea of misinformation, let this note stand as legitimate support for the hypothesis that you can get chicken pox twice.
I had an outbreak 35 years ago when I was 6 years old, clinically diagnosed by Dr. Stanley Milewski in Chicago Illinois (his number was 286-5656, I don't know why I remember that). In early May, 2008 I met with a notable professor in my field. His colleagues told me, "Don't spend time with him if you haven't had chicken pox... he's contagious".
It is important to hobnob with the prominent scientists in the field. Sure, he was sick, but I had the c-pox before, expertly diagnosed, so no problem.
Ten days later I was feverish. Eleven days later I couldn't get out of bed. The next day I had a weird rash on my back and arms. I couldn't figure it out. Then a local MD indicated "the spots are consistent with the lesions formed by chicken pox". Then it hit me- I met with the shingles guy about two weeks earlier, exactly in time with the incubation period of the disease- it's chicken pox! At least it's not Cornish Hen pox or something lame like that.
Here's the tie in with the blog's theme:
Do I know that he gave me the disease? No, there is no way to be 100% certain. However, a rare disease hits me 10 days after I visit, consistent with the normal incubation period. The lesions have liquid filled centers with irregular sides, again, consistent with chicken pox.
Although nay-sayers will tell me otherwise, when we put all of the low-likelihood evidence together, it happened. What are the chances? Probably close to zero. Does the evidence say that it did happen? Yes. Can we make a scientific conclusion from the physical evidence overlayed with the timing? Yes. Rare events do happen in biology, and we can use evidence to reconstruct them with great confidence.