In Peru they do not routinely vaccinate against chicken pox. So I am seeing this disease that I rarely saw in the US, because they started vaccinating kids about the time I finished medical school. Today a young man came in weak, with fever, and this rash all over his body. There were so many vesicles, so tightly bunched together, that at first I did not recognize what I was seeing. It was clear to me however that I did not want what he had and that it looked contagious. As I took a breath and made a second look I realized that it was chicken pox, and that it was possibly the worst case I had ever seen. I immediately wondered whether this patient might have HIV. If he did, then the suppression of the immune system would make chicken pox look terrible. I checked him for encephalitis and pneumonia, both of which can occur with chicken pox in adults. However, the most likely situation, and the outcome in this case is that chicken pox is just worse in adults. Kids rarely look like this, and I guess that is why they had pox parties when we were kids. Parents wanted kids to have it early in life when it is less severe to avoid infections like this as adults. Chicken pox in Peru. An almost absent childhood disease in the US thanks to vaccinations making its mark in Curahuasi.