Officials along the U.S. Gulf Coast have not yet totaled the physical damage caused by Hurricane Katrina. But they are now bracing for the hurricane's next hit: disease caused by a toxic mix of bacteria, human waste and mosquitoes left behind in the floodwaters. Bacterial infections may already be responsible for the deaths of four of the storm's survivors. As VOA's Carol Pearson reports, the health threat from those waters could be just beginning.

In the days after Hurricane Katrina hit the U.S. Gulf Coast, thousands of people trudged through the floodwaters. "This was do or die. It had to be done,” said one survivor.

The trek was more dangerous than they may have realized. Paul Pierce tested a sample of floodwater collected from New Orleans. “In terms of total microorganisms in flood water, this is about as bad as it can get."

Microbiologist Paul Pierce

He said in one sample, bacteria from sewage were 45,000 times the level considered safe to swim in. Mr. Pearce found bacteria from human waste at an astounding 2.2 million parts per unit of floodwater. "The health problems associated with sewage contamination and specifically with these types of organisms can be gastrointestinal problems: dysentery, diarrhea,” said Mr. Pierce. “And that doesn't mean you have to drink the flood water, that just means anything that's come in contact with the flood water is contaminated."

Many of these diseases require a long incubation period. Some of the evacuees from New Orleans are now being treated for an intestinal virus.

Sheriff Jack Stevens

Louisiana Sheriff Jack Stevens says the health risks are growing by the hour. "And we're starting to see skin diseases and rashes and things that are associated with severe bacterial infection."

In children and the elderly these infections can be life threatening, especially in crowded conditions.

Dr. Herbert Dupont

Dr. Herbert Dupont, a specialist with the Infectious Disease Society of America, says there could be many more cases. "If one of them is communicable and has an infectious agent, they could well transmit it to a neighbor."

Other threats from all that water:
West Nile virus -- September is a peak time for this mosquito-borne disease in the United States.
Hepatitis A, a serious liver disease, is also a concern.

The U.S. government has shipped more than 22,000 doses of Hepatitis A vaccine to the region. But that's not nearly enough to protect everyone exposed to the toxic sludge.