Among the doctors stymied from helping out are 100 surgeons and paramedics in a state-of-the-art mobile hospital marooned in rural Mississippi.

"We have tried so hard to do the right thing. It took us 30 hours to get here," said one of the frustrated surgeons, Dr. Preston "Chip" Rich of the University of North Carolina at Chapel Hill.

That government officials can't straighten out the mess and get the doctors assigned to a relief effort now that they are just a few miles away "is just mind-boggling," he said.

Designed to Handle Disasters

The mobile hospital was developed with millions of tax dollars through the Office of Homeland Security after the Sept. 11, 2001, terror attacks. With capacity for 113 beds, it is designed to handle disasters and mass casualties.

Equipment includes ultrasound, digital radiology, satellite Internet and a full pharmacy, enabling doctors to do most types of surgery in the field, including open-chest and abdominal operations.

The mobile hospital travels in a convoy that includes two 53-foot trailers, which on Sunday were parked in a lot 70 miles north of New Orleans because Louisiana officials for several days would not let them deploy to the flooded city, Rich said.

Plans to use the facility and its 100 health professionals had been hatched days before Hurricane Katrina devastated the Gulf Coast, doctors in the caravan said.

Dr. Jeffrey Guy, a trauma surgeon at Vanderbilt University who has been in contact with the mobile hospital doctors, told the Associated Press in a telephone interview, "There are entire hospitals that are contacting me, saying, 'We need to take on patients,' " but they can't get through the bureaucracy.

"The crime of this story is, you've got millions of dollars in assets and it's not deployed," he said. "We mount a better response in a Third World country."

Offers of Help Turned Away

Other doctors also complained that their offers of help were turned away. A primary care physician from Ohio called and e-mailed the US Department of Health and Human Services after seeing a notice on the American Medical Association's Web site about the need for volunteer doctors.

An e-mail reply told him to watch CNN that night when Health and Human Services Secretary Michael Leavitt was to announce a Web address for doctors to enter their names in a database.

"How crazy is that?" he complained in an e-mail to his daughter.

Dr. Bill Winkenwerder, assistant secretary of health affairs for the Defense Department, acknowledged there were problems and said it's a priority "to get the medical community at work and up and operating as soon as possible."

Many other doctors have been able to volunteer and were arriving in large numbers Sunday in Baton Rouge. Several said they worked it out through Louisiana state officials.

Contaminated Water

Meanwhile, the first predictable signs of disease from contaminated water emerged as a Mississippi shelter was closed after 20 residents got sick with dysentery, probably from drinking contaminated water.

However, the country's leading health official told the Associated Press that her biggest concerns are tetanus and childhood diseases.

"Tetanus is something we'd be especially concerned about," said Dr. Julie Gerberding, head of the federal Centers for Disease Control and Prevention.

Tetanus lives in soil and can enter the body easily through a scratch.

Gerberding urged health care workers in the growing multitude of refugee shelters to try to find out a child's shot history. "If you can't establish that a child has been vaccinated, then vaccinate. We can't take chances," she said.

Diseases such as measles and whooping cough could rapidly spread in the cramped quarters that thousands of flood victims are now sharing.

So far, relatively few cases of diarrhea and infections have been reported, Gerberding said, but "we're early in the process."

The CDC chief, who traveled to Louisiana with Leavitt, Surgeon General Dr. Richard Carmona and other top health officials, spoke after visiting a triage center on the basketball court in the Pete Marovich Center at Louisiana State University.