Good Lord!
KALB just interviewed the DHH doctor who heads up the Rapides Parish Health Unit. I think his name was Dr. John Naponick (sp?). He gave a very detailed list of potential health hazards, everything from the items you mentioned to stuff like chainsaw accidents and snakebites and then some. Remember that if someone is forced to climb to a rooftop, that the snakes and rats are heading upstairs, too, so you're not even safe on top of your building. And just imagine having wounds on your body and then being forced to march through infected floor waters, yech. The doctor didn't want to stay on air very long because he wanted to get back to treating people at the shelters. I thought he came across as a very thoughtful physician who has given the matter careful consideration.
Just think of the raw sewage that will be floating around and getting into everything! No one should be out in it.