In all fairness, I need to mention that not ALL public schools in Puerto Rico are dirty with unsanitary practices. In my experience, I have never encountered that issue. Although obviously there are always exceptions which is what this person above experienced.
Also, it is very common for children to randomly get sick during the school season. Regardless, of how healthy they are. This is something I also went through with my own child. When they went to daycare they hardly ever picked up anything from the other kids. However, once they started pre-k they were often sick and for long periods of time.
It's not a Puerto Rico island issue in the same way it's not a stateside issue. It's just the luck of the draw with school aged children. No matter how clean a school is airborne germs really don’t give a damn.