As the death toll in Sunday's tsunamis continues to rise, health authorities are struggling to prevent the outbreak of diseases in the worst affected areas. The disaster hit poor countries whose health systems are inadequate to deal with the scale of the disaster, which may have killed more than 45,000 people.

Authorities in at least 10 Indian Ocean countries are scrambling to dispose of thousands of dead bodies left after walls of water slammed into coastal areas Sunday.

Health experts say the decomposing bodies of humans could contaminate drinking water. Thousands of displaced people are crammed in makeshift camps where poor sanitation could bring about a variety of illnesses.

"The water sources are affected. The food situation may be under stress. People cannot properly cook their food. Hand washing will suffer so that means your personal cleanliness is bad so automatically, it will be diarrheas of different kinds," said Dr. Han Heijnan, the regional advisor for water sanitation at the World Health Organization in New Delhi. "And then sometimes because of the wetness, and the general kind of distress that people are in they might also have a variety of respiratory infections."

Dr. Heijnan said it is a race against time to prevent such outbreaks.

"If people are coming together and maybe temporarily collected in a camp when people are already in a weak state of health, not so well-fed and with poor hygiene, yes, you really have to work fast in order to make sure that people are not falling into disease situation," he added.

A magnitude 9.0 earthquake off the coast off the Indonesian island of Sumatra Sunday triggered tidal waves in India, Sri Lanka, Thailand, Malaysia, Burma, the Maldives and other Indian Ocean islands and as far as eastern Africa. Thousands died and scores of people are still missing.

The nations hit hardest by the quake and tidal waves are poor and the scale of the catastrophe is straining their inadequate health systems.

In the low-lying island-nation of Maldives, health authorities are struggling to deliver what little assistance they can to thousands of victims, some on remote atolls.

Dr. Sheena Moosa, deputy director of health services in the Maldives, says the Maldives lacks medical workers and has little equipment to treat major illnesses.

The thousands of Maldives residents are now packed into shelters. Dr. Moosa says diseases already are spreading among the evacuees.

"The sanitation problem is very bad and water shortage is very, very bad," said Dr. Moosa. "Because the islands have been flooded from one side to the other, the water tanks, the ones that are not fixed to the ground, have been wiped away and the ones on the ground are contaminated. And transporting them, we do not have enough containers to transport water."

Other experts are concerned about the invisible injuries that many of the victims suffer.

Gloria Chen, a spokeswoman for the medical relief agency, Doctors Without Borders, in Hong Kong says psychological problems are harder to heal.

"From our past experience, the people who have undergone such a tragic situation are highly traumatized as they have lost their loved ones, the mental consequences could last for months and even years," she said.

The United Nations says the disaster is the worst in recent history and it is mounting the largest relief effort ever.