This disease is like chicken pox. We all got it as kids and then after had immunity. But what if there was no chicken pox and it only came out today? Well with chicken pox if you didn't get it when older and got it after a certain age it becomes more lethal.

first born from an immigrant family here. My father was bed ridden for a week when he got chicken pox in his 40s, it didnt exist it in his home country.

PS: its called Shingles when you are an adult.