Scores of international rescue teams arrived in the region hoping to stave off disease and homelessness.
With tens of thousands of people still unaccounted for, especially in remote regions, the toll seemed certain to continue climbing.
On Tuesday, Indonesia alone estimated at least 27,000 dead. Sri Lanka estimated more than 16,000 dead, with 4,000 missing.
Several thousand foreign tourists, many of them European, are missing.
As officials struggled to account for the dead and missing, another challenge began to loom: heading off disease.
Rotting food and the use of outdoor toilets by the millions of people rendered homeless by the waves can all create breeding grounds for germs. The year-round tropical climes that made coastal Thailand and Sri Lanka beacons to foreign tourists are now the country's enemies.
Even as local health officials out in the field were racing to create mass graves or pyres to deal with the increasing number of bodies, saying the corpses posed immediate health risks, officials with the World Health Organization emphasized that the biggest risk of an outbreak of diseased was still posed by the survivors.
The agency's officials said Tuesday that because there was little danger of epidemics from unburied bodies, immediate mass burials and cremations were not necessary. Instead, the officials said, family members and friends should be given time, where possible, to identify the bodies. Survivors in Indonesia, India and Sri Lanka complained of the slow pace of national and international relief efforts, news agencies reported. But relief organizations said that given the scale of the devastation across a dozen countries, they were facing what amounted to the largest relief effort in history. ''The initial terror associated with the tsunamis and the earthquake itself may be dwarfed by the longer term suffering of the affected communities,'' David Nabarro, head of crisis operations for the World Health Organization, said in Geneva.
Economists estimated the damage to the region in the billions of dollars.
Word of the horrors on Sunday continued to be reported.
In Banda Aceh in Indonesia, two days after the waves struck, thousands of bloated bodies were still being laid out in fields, morgues and mosques for identification and hasty burial. Television footage showed bulldozers scooping scores of corpses into mass graves that were little more than muddy holes filled with pools of fetid water.
Aceh Province, on the northwestern tip of the island of Sumatra in Indonesia, was the hardest hit by both the earthquake and the resulting tsunamis. Rebels in the civil war in the region declared a cease-fire so that rescue workers could aid those in need. Meanwhile, refugees foraged to survive and extensive looting was reported.
In the Indian state of Tamil Nadu, authorities were struggling to find housing for an estimated 100,000 people left homeless along a 130-mile stretch of coast. Reporters described seeing doctors leave unidentified dead in the open, seeing volunteers lift bodies with their bare hands and seeing corpses carted off in open carriages.
In Sri Lanka, Ramesha Balasuraya, the U.N. Development Program spokeswoman, said the country was in need of virtually everything from medicine to clothing: ''It's main relief items, like water, food, clothing and drugs,'' she said.
An estimated 18,000 to 20,000 foreign tourists who survived the waves have converged on Colombo, the country's capital, according to Sri Lankan Foreign Ministry officials. The city's hotels were packed, with some tourists sleeping in conference rooms. Others were camped in hotel lobbies, awaiting flights out of the country.
At Colombo's modern international airport on Tuesday night, diplomats from various countries arrived to rescue their stranded citizens from a country that until recently was considered a nascent success story. Since a cease-fire in 2002 ended a brutal 20-year civil war, tourism and foreign investment have soared, giving Sri Lanka a relatively stable economy and one of the fastest-growing stock markets in the world.
But as the diplomats stepped off the plane, a smiling young Sri Lankan woman in a luminous green silk sari held a sign that captured the reality of the tear-shaped island nation. Instead of holding a sign that welcomed a tour group, the young woman's sign said ''foreign relief teams.''
The World Health Organization said that contrary to widespread belief, there was no scientific evidence that corpses caused disease outbreaks if they were not buried at once. Experience has shown that the risk of such epidemics is small, two members of the organization's emergency-response team, Rob Holden and Maria Connelly, said in telephone interviews.
Other experts agreed.
There is ''a mind-set even among professionals in the disaster-relief community'' that corpses are a principal source of outbreaks after natural disasters, said Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia University's Mailman School of Public Health.
''But the data shows that corpses are not a reason to have draconian measures that would undermine the ability of loved ones to identify bodies and go through burial rites,'' he said in an interview.
WHO has issued guidelines recommending against mass burials after disasters. Governments should obey religious and cultural principles and traditions where possible, the guidelines state. In most countries, domestic laws specify the requirements for proper disposal of bodies.
But because the numbers of dead in the tsunami vary widely by region, the magnitude of the situation may not allow all governments to follow the burial guidelines.
Connelly said that ''WHO is not dictating'' to governments in the affected areas. ''Obviously, there are certain situations where the guidelines cannot be followed,'' he said. ''If it takes two weeks or so to conduct individual burials, then you could potentially have a public-health disease threat.''
Disease transmission requires the presence of an infectious agent and exposure to it. So if bodies are infected with an organism, they can spread disease. But most infectious agents do not survive long enough in the human body after death, Connelly said.
So the most likely source of outbreaks is from survivors, he said. Health officials are concerned about cholera and other infectious agents present in the affected areas.
