Wednesday, November 15, 2006

A flu pandemic: Could it happen again?

A flu pandemic: Could it happen again?

Newsday Staff Writer

November 13, 2006, 7:30 PM EST

An extraordinarily contagious form of influenza that circumnavigated the globe toward the close of World War I holds the distinction of triggering the most lethal single event in the history of humankind.

Nothing quite like it has occurred since.

As scientists confirmed only last year, the pandemic was caused by a bird flu virus that jumped species.

Now, experts say, the world is overdue for a similar killer strain.

An estimated 50 million people died during the terrifying winter of 1918-1919, the deadliest flu season in the history of the world. More U.S. soldiers succumbed to influenza than died in the war. Indeed, more people died from that illness than lost their lives during the Middle Ages to bubonic plague, a rat-borne bacterial infection that swept unremittingly across Europe between 1348 and 1354.

From a more modern perspective: The AIDS epidemic has killed 25 million people worldwide in 25 years. The great flu pandemic -- known also as the Spanish flu -- killed twice that number in only a matter of months.

Could such a flu season flare again?

"Certainly another pandemic can occur," said Dr. John Oxford, a virologist at Queen Mary's School of Medicine in London and one of the world's leading influenza experts.

"The World Health Organization and the United Nations are both in agreement with that. All of the conditions exist for a virus like H5N1 to take off," Oxford said, referring to the current flu strain responsible for avian influenza.

Dr. Michael Greger, director of public health and animal agriculture at the Humane Society of the United States, also believes the makings of a pandemic already are here.

"Bird flu has gone from snowflake to avalanche. This used to be a very rare disease," Greger said of the infection among birds. "This is not a disease that anyone can miss, because it wipes out entire flocks."

Oxford sees many parallels between the 1918 flu and current avian influenza, which has become a global pandemic among birds. A growing number of human infections have cropped up in Southeast Asia, mostly as a consequence of direct contact with birds. And scattered cases of human illness have emerged in other parts of the world where H5N1 has infected birds.

Gene swap feared

The conditions exist for the disease to become highly contagious, Oxford said. It is possible, Oxford and other scientists theorize, for H5N1 to exchange genes with a common form of flu that routinely infects people. Should this happen, the H5N1 virus could acquire the basic genetic blueprint for spreading quickly -- and explosively -- through human populations. Scientists believe a similar exchange of genetic material occurred prior to 1918.

Because it would be a new virus in humans, it might very well carry a high fatality rate, just like the 1918 flu, Oxford said.

A study reported in August by scientists at the U.S. Centers for Disease Control and Prevention involving ferrets suggested that the "mixing bowl" theory of viral gene exchange didn't seem likely. But they have not ruled it out. Experiments, they say, do not always replicate conditions that occur accidentally in nature.

CDC scientists took genetic material from a common human A-strain of flu and introduced it into the H5N1 strain, and vice versa. Ferrets were used in the experiment because they catch and transmit the flu almost identically to humans, spreading it to each other by coughing and sneezing. The animals emerged from the experiments somewhat weakened but not devastated. To the scientists' surprise, they had not developed a more contagious form of flu.

French roots?

Two years before the 1918 outbreak, cases of a new and unusual respiratory illness were smoldering without much notice among British soldiers assigned to a military base in Etaples, France, Oxford said.

Digging through old medical journals trying to find the beginnings of the 1918 flu pandemic, Oxford and his colleagues ran across a copy of The Lancet from 1916 in which British military physicians described in great detail a series of illnesses diagnosed at the Etaples encampment. Although Oxford's theory differs from that of many American researchers who believe the 1918 flu started at a military base in Kansas, Oxford said the most convincing data suggests the pandemic's roots can be found in France. (Virtually all agree that "Spanish flu" is a misnomer.)

Up to 40,000 men had been processed through the French base on their way to the front lines where the British and their allies were fighting the Germans.

But it seems, at least from what Oxford can discern, that the men were fighting an even more vicious enemy in the camp. In a 145-case sampling documented in the journal report, 50 percent of the soldiers died of their infections. British doctors called the illness infectious bronchitis, something that probably threw off Americans when they read the report.

Soon the French would call it la grippe. Americans would dub it the "great flu," even though it would take until the 1930s for the actual culprit -- a virus -- to be found.

Strikingly, Oxford said, statistics from the 90-year-old medical report are uncannily like those involving human cases of bird flu today.

"To date, the World Health Organization estimates there have been 151 cases [of bird flu] in humans, with a case fatality rate of about 50 percent," Oxford said.

Because the fatality rate in the 1916 sampling was also 50 percent, Oxford sees a parallel that "carries a very strong warning."

Eighty-eight years ago, influenza caught everyone off guard, sweeping ferociously from one corner of the globe to another. Few places were left unscathed.

In 1918, everybody had a flu story if they were lucky enough to live to tell it. The disease was especially devastating among people between the ages of 18 and 40.

Worldwide, people were ordered to wear face masks. If you tried to board a streetcar without one, you could be hauled off to jail. Quarantine was the order of the day. On Long Island, homes became makeshift hospitals.

Symptoms from the 1918 flu included dry cough, high fever and extreme muscle aches. The way that particular flu ravaged the human body mirrors the effects physicians have found in autopsies of people infected with bird flu. Oxford said the body responds in a "cytokine storm" that causes internal bleeding, the result of an immune system gone haywire.

Scientists today are well aware of the 1918 pathogen's virulence because it was reconstructed last year by teams of scientists nationwide, including researchers at Mt. Sinai School of Medicine in Manhattan

A few who lived through the pandemic recorded their horror.

Pulitzer Prize-winning author Katherine Anne Porter, who in 1918 had just begun working as a reporter for the Rocky Mountain News in Colorado, came down with the crippling infection. She would later write about the experience in a trilogy called "Pale Horse, Pale Rider."

This was no simple influenza.

For Porter, who died at the age of 90 in 1980, the memory of it was haunting and indelible, a life-altering experience that pushed her within a whisper of death -- then freed her to tell the story.

Bodies piled like bricks

Throughout the winter of 1918, people were dying so fast a coffin shortage quickly occurred. Even when coffins could be found, there was a shortage of people to bury the dead. Bodies were piled like bricks on streets. Everyone, it seemed, was sick, dying or dead.

But this was 88 years ago. Surely -- certainly -- nothing of this magnitude could surface again?

"Ten years ago there wasn't a single known human infection with bird flu, but now there are several strains of bird flu viruses that have infected people from Hong Kong to Turkey," notes Greger, author of the book "Bird Flu: A Virus of Our Own Hatching."

Bird flu in humans was first diagnosed in 1997 in Hong Kong, and though health officials there ordered the slaughter of millions of birds to stop the virus in its tracks, it cropped up in 2003 in Vietnam in both birds and people.

Last week, Dr. Bu Zhigao and colleagues at the Harbin Veterinary Research Institute in China discovered the gene that makes some strains of the avian infection highly virulent. This knowledge could be used in the development of vaccines to benefit birds, and ultimately humans, scientists say.

Still, Greger says, a single chicken can harbor numerous strains of H5N1. "It takes only a single mutation for a single virus to turn deadly."

Greger estimates that in mainland China alone there are 13 billion chickens. At the time of the last flu pandemic in 1968, he said, there were only 13 million chickens in that country. Presuming 10 percent might be infected now, he believes a staggering number of viruses are probably mutating in the birds.

"We've got to stop encouraging the Western model of poultry production elsewhere in the world," Greger said. "It's a very powerful industry that has grown tremendously in recent years."

With the potential for the emergence of a pandemic strain, Greger said, "people may start questioning whether it's worth risking the lives of millions of people for the sake of cheaper chicken."

Oxford said he believes modern vaccines and antiviral medications, especially those known as neuraminadase inhibitors, such as Tamiflu, will help physicians effectively fight the disease, should a pandemic occur.

"Your government has thrown more cash at this virus than any other flu virus in history," Oxford said of U.S. health officials' ongoing tests of new vaccines and antiviral medications to fight bird flu. "We have two classes of drugs in the medicine cupboard. We could use a few more."

Copyright 2006 Newsday Inc.


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