"The next pandemic will certainly happen," Margaret Chan told reporters following a forum on the need to improve international health security, noting it was impossible to guess when it might happen or how severe it might be.

Since late 2003, the H5N1 strain of bird flu has prompted the slaughter of millions of birds across Asia and caused the deaths of more than 170 people worldwide, about one-third of them in Indonesia, according to WHO.

The virus has been identified in Europe, Africa and the Middle East, in what Chan called an unprecedented spread.

"We cannot let our guard down," Chan said. "My advice for all member states is to maintain vigilance, to prepare for the pandemic. One thing we know for certain is that any country that is prepared will see less damage."

Today's guidelines are partly based on a recent study of how 44 cities fared in the 1918 epidemic conducted jointly by the C.D.C. and the University of Michigan’s medical school. Historians and epidemiologists pored over hospital records and newspaper clippings, trying to determine what factors partly spared some cities and doomed others.

While a few tiny towns escaped the epidemic entirely by cutting off all contact with outside, most cities took less drastic measures. These included isolating the sick and quarantining homes and rooming houses, closing schools, churches, bars and other gathering places, canceling parades, ball games, theaters and other public events, staggering factory hours, barring door-to-door sales, discouraging the use of public transport and encouraging the use of face masks.

The most effective measure seemed to be moving early and quickly. For example, said Dr. Howard Markel, a medical historian and one of the study's leaders, Philadelphia, the worst-hit city, had nearly three times as many sick and dead per capita as St. Louis, which had was hit weeks later by the virus moving inland from the Eastern Seaboard and had time to react as soon as flu cases rose above averages.

"No matter how you set up the model," Dr. Markel said, "the cities that acted earlier and with more layered protective measures fared better."

The deadly H5N1 strain of avian influenza is making a seasonal resurgence in Asia and could easily spread to Europe again this year, the World Health Organisation warned on Sunday.

The alarm follows four human deaths in Indonesia in the last five days, the first human case in China for six months (though the infected man has since recovered) and new poultry outbreaks in Vietnam – despite a huge campaign against it – and northern Nigeria.

"We are convinced that we're in a repeat of last year and the year before when the virus began to get very active again [in the northern hemisphere winter] and spread from Asia into the Middle East and beyond," said Peter Cordingley, the WHO spokesman for the western Pacific region.

Indonesia, where 61 people have died since 2005, remained the "biggest flashpoint" but nowhere in the region "has got it licked". "Most countries are becoming better prepared and the countries that were caught out last year, especially wealthier ones in Europe and close to Europe, we hope are going to be better prepared," he said. "But we're still losing more than we're winning."

Doctors were completely unable to stop or slow its spread; the killer flu eventually traveled to the general population and worked its way from East to West across the United States. The influenza spread so fast that hospitals and morgues were quickly overrun. People were often forced to live with the dead bodies of family members because there were so many dead and dying that the health system and city morgues were completely overwhelmed. Many health workers were also sick and dying themselves. Coffins quickly became unavailable and bodies were stacked up on porches and next to houses. Symptoms of the disease were terrifying and violent: incredible pain, blood pouring from noses and eyes, intense fever, headache, weakness, body aches and delirium. People often died after gasping for breath for hours trying to clear a red, frothy liquid from their lungs. Mayors in cities lied to their citizens and said the plague would not come. But it came and even during the epidemic many newspapers reported that there was no cause for alarm or told people the virus had peaked when it had not. In 1918, influenza was a killing machine that raged from coast to coast, killing over 600,000 Americans. In October, 1918 influenza killed 195,000 Americans in a single month.

"There will be a reasonable possibility of a domestic fowl outbreak" as migrating birds mix with ducks, chickens and other birds in the U.S," Chertoff said. But he cautioned against panic, noting that the Agriculture Department has dealt with other strains of bird flu for years.

"If we get a wild bird or even a domestic chicken that gets infected with avian flu, we're going to be able to deal with it, because we've got a lot of experience with that," Chertoff said, speaking to newspaper editors and publishers.

"There's no way you can protect the United States by building a big cage around it and preventing wild birds from flying in and out," U.S. Secretary of Agriculture Michael Johanns said.

U.S. spy satellites are tracking the infected flocks, which started in Asia and are now heading north to Siberia and Alaska, where they will soon mingle with flocks from the North American flyways.

"What we're watching in real time is evolution," said Laurie Garrett, a senior fellow for global health at the Council on Foreign Relations. "And it's a biological process, and it is, by definition, unpredictable."

Since then, government and health officials have been swarming the place, trying to control the spread of the deadly disease.

For years, the people of Navapur had to contend with bad roads, poor electricity and social issues such as deaths of children due to malnutrition.

Now they have to deal with bird flu - and many of them do not even know what it is, let alone how it is spread.

All areas within 3km (nearly 2 miles) of Navapur have been quarantined and 60 medical teams have been deployed in the area with a clear brief of slaughtering all the chickens - nearly 900,000 in number.

Guenael Rodier, a special adviser on communicable diseases at the WHO, told the BBC that while he was not surprised by the case, it was a significant development.

"It shows a geographic extension of human cases and certainly increases altogether the overall likelihood that at some point this virus will adapt to humans," he said.

"So it's important this is going to be investigated, and a WHO team is on its way to the Far East and Turkey with nationals to investigate."

Amid the flu fears there actually was a lot of good news this year. Cancer overtook heart disease as the leading cause of death among Americans 85 and under. Why is that good, you ask? Because deaths from both are falling, it's just that those from heart disease have fallen more dramatically.

Two vaccines proved effective against human papilloma virus, or HPV, the leading cause of cervical cancer, a big killer around the world.

New-generation cancer drugs like Avastin and Herceptin, which more precisely target the disease and leave healthy cells alone, also scored big victories in studies on lung and breast cancer patients respectively, notes the American Society of Clinical Oncology in its first annual report on cancer progress.

Five years ago, these drugs were in the "hope" stage but now are in wide use, said Dr. Roy Herbst, a lung cancer expert at the University of Texas M.D. Anderson Cancer Center.

Claims made by the companies about their treatments include phrases like "prevents avian flu," "a natural virus shield" and "kills the virus," the FDA said.

Because of these claims, the agency considers their products, most of which are marketed as dietary supplements, to be new drugs that require approval before they can be sold.

The nine companies are: Sacred Mountain Management Inc., BODeSTORE.com, Melvin Williams, Iceland Health Inc., PolyCil Health Inc., PRB Pharmaceuticals Inc., Chozyn LLC, Vitacost.com and Healthworks 2000.

In China's human cases, the virus has mutated "to a certain degree," health ministry spokesman Mao Qun'an was quoted as saying.

"But the mutation cannot cause human-to-human transmission of the avian flu," he noted.

China this month confirmed its first three human cases of bird flu, two of which were fatal. The disease has killed more than 60 people in Asia since 2003.

Health officials fear that the virus could mutate to the extent where it is easily transmitted from human-to-human, an event that could lead to a global pandemic capable of killing hundreds of millions of people.

Canada has discovered a strain of H5 avian flu in 33 wild migratory ducks but it is unlikely to be the killer H5N1 strain which has spread from Southeast Asia to Europe, a top health official said Monday.

Jim Clark of the Canadian Food Inspection Agency said a recent survey of 4,800 healthy wild birds had found the H5 virus in 28 ducks in the eastern province of Quebec and five in the central province of Manitoba.

While most Siberian flocks don’t try to cross the Pacific to North America, some do cross the narrow Bering Strait to Alaska.

If those birds mingle with birds from Alaska, "there is the possibility the virus could be transmitted to waterfowl or shorebirds that make their way here next fall," Brand said.

While many severely infected birds usually die within a few days and are unable to fly very far, other hardier varieties could carry the disease.

Among the Arctic species under suspicion are hardier, long-distance fliers like eiders, gulls and geese. "It probably will be spread by one that isn’t killed very easily by it," Brand said.

Maliuc joins the Danube delta village of Ceamurlia de Jos as the second place in Romania to have confirmed it has the virus.

Preliminary tests suggest bird flu has also arrived in European Russia, west of the Ural mountains, having been found in Asian Siberia already.

Russian laboratories said H5N1 had been detected in birds in Tula, about 220km (137 miles) south of Moscow.

"The burning question is, you know, will there be a human influenza pandemic?” said Dr. Lee. “I believe, on behalf of WHO, I can tell you that there will be. And right now the only one condition missing is the virus that is rapidly transmitted from human to human."

And the bird flu keeps spreading. In the past few days, the avian flu was detected in two European nations. Officials restricted access to a Romanian village after three ducks were found dead from the virus. And in Turkey, 3,000 turkeys and chickens were culled after another 1800 turkeys died of the disease last week. To prevent the further spread of the disease, Turkish officials have indicated they will continue to kill poultry in the affected area for the next three weeks.

Leavitt said "containment" was the first line of defense against the illness, encouraging countries to step up development and production of vaccines and strengthen efforts to detect any cases of human-to-human transmission early.

"Anywhere, the sooner we know, the faster we can respond and the more lives that will be saved," he said.