A cross stands at the edge of Sissano lagoon

In this story:

• Plan to blast lagoon open to sea
• Albright to stop in Papua New Guinea next week

SISSANO, Papua New Guinea (CNN) -- The lagoon in northwestern Papua New Guinea where thousands were swept to their deaths by tidal waves has been sealed off to prevent disease, and officials believe the precise death toll may never be known.

A state of emergency has been declared on the Sissano coast and up to 45 square miles (120 sq km) have been sealed off because of the fear of disease, not only from the corpses in Sissano lagoon but from hundreds more buried in shallow graves among the surviving villages.

Australian government officials said on Friday that the official death toll from last Friday's tsunami stood at 1,500.

About 5,200 people were in care centers and 700 in provincial hospitals and an Australian army field hospital, officials said.

An estimated 10,000 people lived on the spit of land between the lagoon and the Pacific Ocean that was ravaged by the 23-foot (7-meter) earthquake-generated waves six days ago.

RELATED AUDIO

Major Doug Wren, Australian Army "...putting up signs to warn people away from the lagoon." 187K/8 sec. AIFF or WAV sound

Papua New Guinea officials plan to allow the Sissano lagoon corpses to decay naturally before blasting open the mouth of the lagoon and to allow the ocean and tides to drain the waste.

Capt. C. Wapar told Reuters that 616 lbs. (280 kg) of explosives were flown to Vanimo, west of Sissano, on Thursday. "They are going to blow up the mouth of the lagoon to let it drain out to sea," Wapar said.

A team of American sniffer dogs was airlifted Friday into the disaster area to search for survivors in swamps behind Sissano lagoon.

Relief officials hope the dogs, a Siberian husky and three German shepherds, may find survivors, possibly children, too scared or unable because of injuries to come out from where they were driven by three tsunamis which devastated the area six days ago.

The Florida-based sniffer dogs are trained to track bodies under water and in swampy land.

"If someone is scared and they are actively attempting to evade you, they hear you coming," said Arthur Wolf, one of 10 serving Miami policemen and firemen who have voluntarily brought the specially trained dogs to Papua New Guinea.

"A trained dog can pick up a human scent, depending on the terrain, several hundred meters away and then the dog can lead us in to them," Wolf said on Friday.

On Thursday, the United States delivered relief supplies to the capital Port Moresby. These included tents, beds, clothing, water containers, tools, lanterns and medical supplies.

U.S. Secretary of State Madeleine Albright will make a brief stop in Port Moresby next week to discuss how the United States can help the Pacific nation reconstruct.

Surgical teams in a tent hospital continued the task Friday of trying to save the battered survivors, many of them affected by gangrene. Nearly 200 operations had been performed since Monday.

Most injuries happened when the tsunami flung people against trees or debris, fracturing bones and tearing open skin. Many people died instantly; others died in the jungle before medical help could reach them.

Doctors say the biggest danger to the injured now is infection. Coral sand ground into open wounds contains bacteria that thrive in the tropical climate.

Lt. Brad Slater, an Australian army officer at the emergency field hospital in Vanimo, said the facility had also treated many pneumonia cases brought on by breathing seawater.

At least 30 bodies were found Thursday washed up on a beach in the Indonesian province of Irian Jaya, about 25 miles (40 km) west of the disaster zone, local police said, on condition of anonymity.

Those victims were believed to have been sucked out to sea by the back surge from the waves and dragged along the coast.

Hundreds of terrified survivors have fled to inland villages, vowing never to return to the coast. With nowhere to go -- no homes, little food and water -- they sit, unsure of the future, in the dirt under plastic tarpaulins

The exodus from the Sissano lagoon area has put pressure on relief officials to house and feed the growing refugee population, and new, makeshift villages are emerging in the jungle.