This is an interesting article on public-health fears in the wake of Katrina (well, I found it interesting, having been assigned to do a factbox on cholera and dysentary until we realized they weren’t major threats):
Diarrheal disease from contaminated water is a concern, but not cholera and probably not typhoid. In order to get these diseases the water has to be contaminated with the organisms that cause those diseases, neither of which is endemic in that region. What is more likely is gastroenteritis or hepatitis A from enteric viruses or bacteria. …
Similarly the presence of dead animals and people is not a health hazard. Dead animals decompose naturally in the environment. Unless they were infected with a contagious organism before death, they will not themselves become the source of disease. The persisten concern in mass disasters over unburied bodies is an urban myth. Mass disasters like floods rarely cause epidemic disease and to suggest otherwise results in misplaced concern and potential diversion of resources from more important issues.
Mosquito-borne illness is a potential concern for some, but needs to be properly understood. Being bitten by mosquitoes is not a health hazard. The mosquitoes themselves must be vectors for a pathogenic agent like malaria or West Nile.
CNN’s coverage has been awesome, IMHO, but Wolf Blitzer keeps repeating the mosquito danger without explaining it well. E. Coli, from what I understand, is definitely to be expected.
My profession is microbiology medical technologist, so when my friends were all gasping that horrors! There was E. coli in the water in NO! I just shook my head. Yep, and probably in the mud puddles outside your home from doggie doo, too. And definitely in your toilet bowl, your faucets, and the doorknobs to your bathroom unless you just doused them with Lysol.
E. coli simply means there is sewage in the water, which is to be expected when the sewers back up. You don’t want it there because it shows there is sewage in the water, and that may spread other diseases. But regular old E. coli probably wouldn’t make you sick – your gut is already full of it, literally, it is “normal flora.” But it may be a sign of other bacteria and viruses from the sewage that may make you sick. E coli and its cousins, the coliform bacteria, are an indicator that a water supply is contaminated with sewage or manure.
Enteropathogenic E. coli, the kind that gives you bloody diarrhea, is not typical in sewage. It is found in some slaughterhouses and may contaminate ground beef. It is a nastier form that makes a toxin which makes you sick. But it must be in a large amount, such as happily growing in an under-refrigerated and undercooked patty, to cause illness.
I always assume any open water supply must be filtered, boiled, or made potable with iodine or chlorine before drinking it. In my neck of the woods (Oregon) all of the sparkling mountain streams have Giardia lamblia, an adorable little flaggelate microbe that gives you nasty, long-lasting diarrhea and must be treated with some very nasty drugs. Don’t drink the water – filter, boil, bleach.
I actually bought a Katadyn “Hiker Pro” water filter when I was in Colorado last month … pretty cool and easy to use.