As avian flu spreads, Alaska is on lookout

Months earlier, summer breezes had carried wild birds from Asia to this little pond. Now, with the temperature at 9 degrees, Runstadler bored through the frozen surface in search of the seeds of a pandemic.

"Ground Zero is what's in birds," said the University of Alaska molecular biologist, who dropped hockey puck-shaped ice samples into a Ziploc bag.

This snowy patch of the Alaska wilderness sits at the edge of a bird flu outbreak that emerged in Hong Kong in 1997 and has recently spread as far as Kazakhstan, Croatia and Siberia. The virus has ravaged farms in Thailand and felled wild birds from western China to Eastern Europe.

Turkey has become the latest hot spot, reporting at least three human deaths from bird flu since the start of the year -- the first human cases outside Asia.

Since 2003, the virus has killed 76 people, according to the World Health Organization. More than half died in the last year.

What Americans once viewed as a distant scourge is now just across the Bering Strait. If it arrives in North America, scientists expect to find it first in Alaska, a breeding ground for many migratory birds from Asia.

The bird flu virus, known as H5N1, is the culmination of random mutations and countless viral mixings, producing a strain of influenza unfamiliar to the human immune system.

It could be just a few more mutations away from being able to easily infect and spread among people -- the raw ingredients needed to spark a global pandemic. Or it could evolve into a harmless strain.

The virus is not so different from the common flu that causes fevers and runny noses each winter. Yet it has provoked a degree of fear that belies its mundane origins.

Governments have slaughtered millions of chickens and other poultry. Hospitals are stockpiling Tamiflu and other antiviral medications. Scientists are racing to develop a vaccine.

In Alaska, scientists such as Runstadler are searching for traces of H5N1 in bird droppings left from the summer breeding season. They could be preserved in now-frozen water or soil.

"It's just a matter of time before H5N1 shows up everywhere," said George M. Happ, a UA biologist who is coordinating the state's pursuit of the virus.

ONE CASE IN HONG KONG

In May 1997, there was panic in Hong Kong over an outbreak of German measles that sickened more than 1,500 people, mostly teenagers.

Amid the commotion, a 3-year-old boy with fever, aches and a sore throat was admitted to a Kowloon hospital. He had typical flu symptoms, nothing unusual in a young child.

Yet as the days progressed, the boy's illness continued to worsen. His symptoms indicated viral pneumonia and Reye's syndrome, a rare disorder that causes brain inflammation. He died six days after being admitted to the hospital.

Dr. Wilina Lim, a virologist with Hong Kong's Department of Health, tested a fluid sample from the boy's windpipe. She confirmed it was an influenza virus but couldn't identify it.

Lim sent off samples to two of the top infectious disease laboratories in the world -- the U.S. Centers for Disease Control and Prevention in Atlanta and the National Influenza Centre in the Netherlands. Three months later, she received a startling reply: The boy had been infected with a virus that had been found only in birds.

Kennedy Shortridge, a University of Hong Kong microbiologist, had identified a nearly identical virus a few months earlier as the cause of 4,500 chickens' deaths on farms in Hong Kong's Yuen Long district.

It was the first documented case of bird flu jumping directly to humans with lethal consequences.

New patients came down with H5N1 in November 1997. All but one had visited Hong Kong's live poultry markets within several days of the onset of their symptoms. Altogether, 18 people came down with severe respiratory illness. Six of them died.

Because the outbreak coincided with the onset of the regular flu season, health officials worried that H5N1 could mix with a human flu strain and morph into an easily transmissible virus.

Hong Kong's health director, Margaret Chan, ordered the culling of all poultry in the territory. Secretaries, park rangers and dog catchers were drafted to help slaughter 1.6 million chickens, ducks, quails, partridges and geese. There were no more human cases that season.

REPEATING HISTORY

In the spring of 1918, while the world was at war, a mysterious bug sickened soldiers in Kansas and spread to other American military camps. Amid the global commotion, the virus propagated quickly, affecting healthy adults as well as children and the elderly.

The virus claimed the lives of so many Spaniards in May alone, it was given the name the Spanish flu.

By the time it receded the following year, as many as 50 million people had died, including more than 500,000 in the United States. More soldiers of all nations were killed by the Spanish flu than by World War I combat.

Remnants of the Spanish flu virus mixed with a strain of avian influenza in China and became the 1957 Asian flu. It caused as many as 2 million deaths, including about 70,000 in the United States.

That gave way to another pandemic virus in 1968 known as the Hong Kong flu, which killed 34,000 Americans and about 70,000 people worldwide.

Scientists worry that the H5N1 virus could be next.

The virus resurfaced in Asia in 2001 and has been spreading steadily from its epicenter in southern China since 2003. Vietnam, Thailand, Cambodia, Indonesia and China reported 39 deaths last year, according to the WHO.

CONSTANT CHANGE

The influenza virus is a simple device. Each spherical flu particle contains eight strands of RNA, which have instructions for making 10 proteins. Two of these are hemagglutinin and neuraminidase.

Scientists have identified 16 types of hemagglutinin, or H, and nine kinds of neuraminidase, or N. The combination is what gives a flu its name.

Unlike more complex organisms, whose genetic code is stored in DNA, flu viruses have RNA, which cannot copy itself reliably. Each mutation changes the shape of the H and N proteins, and over time, the immune system fails to recognize them.

This genetic "drift" is why the flu vaccine must be updated every year. Even small drifts enable viruses to sicken millions of Americans each winter and kill an average of 36,000.

A more dramatic event is a "shift," which occurs when two flu viruses infect a cell at the same time and swap entire strands of RNA. The mixing could involve two kinds of human flu, or it could include strains from birds, pigs, horses, seals, whales or other animals.

The most dangerous scenario is for a human virus to exchange its H -- or both its H and N -- with an animal equivalent. The combination probably would create a new strain, and no one would be immune. It would take months to develop a vaccine.

There have been 146 documented human cases since 2003, the WHO said. Each new case increases the possibility of a deadly mutation.

FRONT LINES

In July, Runstadler flew to the tidal flats of Chevak to spend a week testing black brant geese for signs of H5N1. The birds were molting their feathers, making them easier to catch.

The researchers can't tell if an individual bird came from Asia, but they know that some of the species they are monitoring -- including brant geese, pintails, mallards and godwits -- migrate from the other side of the Pacific.

"It's good to get anything we can because we're starting from a knowledge base of essentially zero," Runstadler said.

Scientists surmise that migratory birds carrying H5N1 in their guts have transported the virus far from its origin in southern China as they traverse the vast aerial interstates that crisscross the globe. The eight major flyways cover nearly every speck of land on Earth -- with the exception of Antarctica -- and they all overlap.

Infected birds from China flying along the Central Asia flyway could have mixed with birds from the neighboring East Africa-West Asia flyway, bringing the virus to Kazakhstan in August.

From there, it's an easy jump to the Black Sea-Mediterranean flyway, which encompasses Romania, Turkey and Croatia -- three countries where birds tested positive for H5N1 in October.

The East Asia-Australia flyway, which stretches from Australia to Siberia and over to Alaska, would be the likely route for bringing the virus to North America. Once in Alaska, migratory birds could pick it up and carry it south along the Pacific Americas flyway or the Mississippi Americas flyway, which encompass most of the Western Hemisphere.

Government officials thought they could contain the spread of H5N1 by culling millions of farm birds. That notion now seems quaint, as wild birds have become a permanent natural reservoir for the virus.

Detecting the first signs of H5N1's arrival here will give farmers and public health officials crucial time to ready their defenses, said Dr. John Clifford, chief veterinarian at the U.S. Department of Agriculture.

This summer, in the marshy land of Chevak, Runstadler and his fellow researchers corralled brant geese into a temporary pen. Then he began collecting samples from each bird's hindquarters with the gentle rub of a Dacron swab. The swabs were placed in ethanol to preserve any virus that might be present.

The weeklong effort produced samples from more than 1,000 migratory birds. Similar efforts around the state yielded 4,000 more samples from mid-May to late September.

About 500 of the samples have been screened so far. More than 15 percent have tested positive for avian influenza.

So far, none of the strains are H5N1. The birds, however, will return in the spring.