The death toll from Hurricane Katrina and its aftermath is in the thousands, US Health and Human Services Secretary Michael Leavitt revealed for the first time Sunday.

Leavitt told CNN television he had no precise death toll but said: "I think it's evident it's in the thousands."

Earlier in the day, Homeland Security Secretary Michael Chertoff had declined to estimate the death toll, but conceded that an untold number of people could have perished in swamped homes and temporary shelters where many went for days without food or water.

"I think we need to prepare the country for what's coming," Chertoff said.

Leavitt acknowledged a case of dysentry in Mississippi and warned of the growing danger of epidemics.

Media reports said dysentry had been confirmed in Biloxi, Mississippi, and that an emergency shelter in the Gulf Coast port had been closed.

The lack of clean drinking water in parts of the Gulf Coast region and standing flood waters with decomposing bodies and human waste in the streets of New Orleans could cause a rash of infectious diseases, including West Nile virus and the often fatal E. coli bacteria.

Washington has been criticized for moving too slowly in the storm's aftermath.

"The world saw this tidal wave of disaster descend upon the Gulf Coast," Bush said Sunday during a visit to the Red Cross disaster operations center in Washington, where he urged Americans to donate money, time and blood to the relief effort. "Now they're going to see a tidal wave of compassion."

Bush also planned a return to the storm-ravaged region on Monday for a third look at Katrina's effect with visits to Baton Rouge, La., and Poplarville, Miss.

Source: Xinhua/agencies