"The worst is yet to come, I am afraid, because of the breakdown in sanitation facilities," said Dr. Robert Edelman, a professor of medicine and vaccine expert at the University of Maryland.

Getting clean water to the millions of people affected will be the first step, but an overwhelming one, said Dr. Gilbert Burnham, Co-Director of the Center for International Emergency, Disaster and Refugee Studies at Johns Hopkins University in Baltimore.

"Where are you going to find a million plastic buckets in Sri Lanka right now?" Burnham asked in a telephone interview.

The earthquake off the coast of Indonesia and tsunami that swept shores from Thailand to Sri Lanka have killed at least 125,000 people, according to estimates.

Although people traditionally fear that unburied bodies carry disease, health experts agreed there was little danger.

"Cholera is certainly not contracted by dealing with dead bodies, that is for sure," Edelman said. Decomposing bodies may make water unpalatable, he said, but do not make it toxic.

"The cholera organism doesn't concern me as much as other organisms like shigella or E. coli," added Edelman.

"These bacteria cause diarrhea and also have the propensity to infect children as well as older adults." Both can be deadly if patients are not rehydrated with special solutions.

Preventing diarrheal disease is easy with clean water, but the widespread, heavy and sudden flooding destroyed power stations, idling water pumps. Floods also probably filled wells and swept away plumbing and even water buckets.

"You can purify water by boiling it but there is no fuel, or put something into it like iodine or chlorine, which most people probably don't have," Edelman said.

MAKING WATER SAFE

Recent studies have shown that cholera bacteria, and presumably others, can be safely filtered from water using a folded sari or sarong. Folding the fabric four times cut the infection rate in half, University of Maryland experts found.

Another study has shown that water left to stand in the sunlight for a day in a plastic bottle becomes safer to drink.

"In fact, if you just let water sit and settle out, that has a positive effect," Burnham said. "But people have been emotionally traumatized and it is extremely difficult for them to think in that organized a fashion."

And Linda Young Landesman of New York's Columbia University, who wrote a book entitled "Public Health Management of Disasters: The Practice Guide", said it may be impossible to educate people about such low-tech measures.

"There has to be a mechanism to communicate, to do public health education and how are you going to do that?" Landesman asked. "They don't have TVs. They don't have radios -- or if they do, are they functioning now?"

Edelman said another wave of disease will come as mosquitoes move in to devastated areas.

"People will be out under the stars and in tents," he said.

"There will be big masses of people sleeping together. This is tailor-made for the transmission of viruses, for instance dengue fever," said Edelman, who is working to develop a vaccine against dengue fever.