I am not sure that DPC or Superdome incidents occur after most disasters. There are many variables in play. In Southern California, which has seen it share of disasters (e.g., Sylmar and Northridge EQs), shelters which were set up are usually sparsely attended. In an urban situation like New Orleans, disasters scenarios may well play out differently. But, although the helpful sources you cite talk about the concern about disease and epidemics, there is no note of any significant uptick in disease. Your first article gives some definite numbers, but there is no comparison (that I saw, anyway) that compares those occurrences with "normal"conditions.

I suppose it is worth pointing out that in addition to washing hands and keeping generally clean, it is a good idea to get your shots and vaccinations - another subject about as thrilling as watching paint dry. But getting your flu shots will really pay off, and it is cost effective to boot.