The grim situation of Hurricane Katrina survivors threatens both their physical and mental health, experts say.

Public health officials are still trying to come to grips with the extent of the disaster in New Orleans and along the devastated Gulf Coast. They're sure of only one thing: It's far from over.

"This is worse than anything we ever dreamed of," Carlos del Rio, MD, chief of medicine at Atlanta's Grady Memorial Hospital, tells WebMD. "I don't see any end in sight."

"It is a public health disaster of the first rank. This is something I never imagined happening in the U.S.," Roger Lewis, PhD, director of the environmental health research lab at Saint Louis University, tells WebMD.

The scale of the disaster staggers even G. PatriciaCantwell, MD, director of the pediatric intensive care unit at the University of Miami-affiliated Holtz Children's Hospital. As medical manager for South Florida's FEMA urban search and rescue team task force, Cantwell has been deployed for disasters as diverse as Hurricane Andrew and the attack on the World Trade Center.

"The whole premise of dealing with the flooding and with supplies and with medical care -- this is totally overwhelming," Cantwell tells WebMD. "I can't even fathom the process of organizing relief efforts. The victims are going to be so frustrated with the time it takes to get supplies to them. But the problems of getting them there are nearly incomprehensible."

Bad Water

In New Orleans, flooding is making a bad situation worse. It won't be solved anytime soon, Lewis says.

Floodwaters are contaminated with human and industrial waste. Such water contaminates anything it touches -- and people, many with open wounds, must wade or swim through it to reach high ground.

The municipal drinking water in New Orleans is contaminated by floodwater. Only bottled water is safe to drink. And bottled water is in critically short supply.

Those forced to drink contaminated water risk the many diseases associated with human waste. The run-of-the-mill bacterial infections are serious enough: E. coli, shigella, and giardia infections, for example. More exotic diseases are possible. One, del Rio and Cantwell warn, is cholera, which endures in the oyster beds near New Orleans.

All of these water-borne diseases cause diarrhea, often with vomiting. These diseases quickly dehydrate victims, who need fresh water and medical attention. In the unsanitary conditions prevailing in New Orleans, diarrheal diseases spread like wildfire.

"And another thing to keep in mind is that many of these people have sustained some kind of injury, whether a laceration from glass or whatever," Cantwell says. "By the time those wounds reach medical care, there is the potential for them to become infected. This is compounded by the fact that sewage pipes are flooded and excrement is going to be everywhere in the standing water."

Standing water is where mosquitoes breed as well. While malaria and dengue are not likely problems in the U.S., the threat of mosquito-borne encephalitis viruses is very real.

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Mental Health

Television images of panicked crowds mobbing evacuation buses are vivid reminders that deteriorating mental health is an enormous issue in New Orleans.

The situation is an ugly reminder that disasters bring out both the best and worst sides of human nature, says University of Miami psychiatry professor Jon A. Shaw, MD. Shaw is a consultant on terrorism and disaster for the National Child Traumatic Stress Network. He was, and is, closely involved in the Hurricane Andrew relief effort.

"The initial response to disaster is coming together as a group, as you saw after 9/11," Shaw tells WebMD. "Then, with increasing awareness of lack of resources, there is fragmentation. That is when you see the absolute worst of human nature. People compete for resources. You see looting, violence, exploitation, and opportunistic crime."

Shaw notes that in most disasters, there is a heroic phase in which people feel a strong sense of community with other survivors. This is followed by a terrific sense of expectation as people rush in to help. As time goes by, people generally become frustrated with the pace and incompleteness of the relief process. But even this is part of a slow process of recovery.

That's not the case in New Orleans.

"Here there are all these secondary events more traumatic than the original one -- all these continuing threats to health and vulnerability to disease," Shaw says. "People get a sense of hopelessness and helplessness. They have no confident expectation that anything good is going to happen. It is kind of like the death of a city. It is a very sad, very tragic scene."

Even when help finally arrives and doctors treat all of the illnesses and injuries, mental healing will still be going on.

"We saw after Hurricane Andrew the risk for psychological problems insidiously increases over time," Shaw says. "Even two years later, some of the children had more behavioral and emotional problems than in the immediate aftermath, because of the additional stressors. You had the absolute destruction of the infrastructure of a community."

Those problems are, by every account, worse in the areas struck by Hurricane Katrina. Usually, healing comes from connection with family members and friends and a return to a semblance of normal life. In the disconnected aftermath of Katrina, none of this currently exists. And it isn't clear when, if ever, it will.

"Ordinarily when we try to help people after a disaster, we think what is the next step," Shaw says. "Empower yourself. Achieve mastery over anxiety. In most disasters you can do that. But here it is not clear what the next step is for most of these people other than just to survive. It is horrific. It is hard to overstate the stressors: loss of life, injuries, loss of loved ones, separation from social networks, loss of shelter, and lack of both physical and economic security."

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The Elderly

The brunt of any disaster is borne by the youngest and the oldest members of society. As a society, we tend to focus on children. And we tend to forget the elderly.

Most elderly people live on their own, says Nina Tumosa, PhD, professor of geriatrics at Saint Louis University School of Medicine. When they're stranded by a disaster, there's no master map that shows where they live. Yet many of these people need daily medications. Many rely on meals brought to them by others. And many lack the resources needed to escape a dangerous situation.

"We do not keep track of those people. We don't know where they live," Tumosa tells WebMD. "We don't know how many there are, how many are immobile, and how many are on oxygen. We do not know the women at 1234 Elm Street is diabetic, that she needs home-delivered meals, or that she has a heart problem."

Finding the elderly, Tumosa says, requires a house-to-house search. And even when they are rescued, their problems are far from over.

"Communication is the major problem," she says. "They are worried about their whole family, about food and water, about where they go, about how to tell their children where they are. They worry about how to find a doctor and get a new prescription. They may have lost their glasses; their hearing-aid batteries may have gone out."

Help -- and Keep On Helping

It's clear that nobody yet knows the extent of this catastrophe. One thing, however, is clear. People need help. And they will keep on needing help for a long time -- even after their considerable physical needs are met.

"There are going to be a lot of issues in refugees," del Rio says. "They will need care, of course. But the major issue is that they are going to need a lot of mental health services. They are traumatized. Their lives have changed in a very dramatic, very critical way."

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By Daniel J. DeNoon, reviewed by Brunilda Nazario, MD

SOURCES: Carlos del Rio, MD, chief of medicine, Grady Memorial Hospital, Atlanta. Roger Lewis, PhD, director, Environmental Health Research Lab; associate professor, Saint Louis University School of Public Health. Jon A. Shaw, MD, professor of psychiatry; director, division of child and adolescent psychiatry, University of Miami; consultant on terrorism and disaster, National Child Traumatic Stress Network. Nina Tumosa, PhD, professor of geriatrics, Saint Louis University School of Medicine; health educator, Veteran Affairs Medical Center, St. Louis.