Alan Sipress - The Fatal Strain

Once the virus was established in Nigeria, the epidemic spread, most likely along internal trade routes, and put neighboring countries in jeopardy because of widespread cross-border commerce. By the close of 2007, eleven African governments had reported outbreaks in birds, some in countries no better able than the poorest in Asia to confront the disease.

A rancorous debate has erupted over exactly how avian flu spreads.

Are wild birds the culprit, conveying the virus on their seasonal migrations? Or is it trade in poultry, legal or not, that inadvertently extends the global reach? Some wildlife conservation groups have said that migratory patterns aren’t a good match for the distribution of outbreaks, suggesting instead that the virus spread from Asia to Europe by commerce along the route of the Trans-Siberian Railroad. But other researchers have noted outbreaks near wintering sites for migratory birds and far from any farms or markets that could account for contamination. After more than a decade, there is now enough evidence to conclude that the novel strain has taken ample advantage of both these opportunities to advance across the Eastern Hemisphere.

Some countries have been able at times to roll back the tide of infection, notably those in Europe and more developed Asian states like Japan and South Korea. But elsewhere, the disease refused to surrender its foothold.

No one is better positioned to evaluate the viral storm gathering in the animal kingdom than Joseph Domenech, chief veterinarian of the UN Food and Agriculture Organization. In a series of public warnings starting in the fall of 2007 and running into 2008, Domenech offered a disturbing, though not universally bleak prognosis. “Surveillance and early detection and immediate response have improved and many newly infected countries have managed to eliminate the virus from poultry,” he reported. “But,” he continued, “the H5N1 avian influenza crisis is far from over.”

He singled out Indonesia as the place where bird flu had become most stubbornly entrenched. “I am deeply concerned that the high level of virus circulation in birds in the country could create conditions for the virus to mutate and to finally cause a human influenza pandemic,” Domenech said in another assessment in March 2008. “The avian influenza situation in Indonesia is grave—all international partners and national authorities need to step up their efforts for halting the spread of the disease in animals and making the fight against the virus a top priority.” He faulted a lack of money, poor coordination among different levels of government in Indonesia’s decentralized political system, and insufficient commitment. With the strain in Indonesia actively undergoing genetic changes, Domenech warned that the virus was spinning off new subtypes that could elude the poultry vaccines meant to contain it.

Even when outbreaks ebb, it doesn’t mean flu has been beaten. It goes to ground, smolders, waits for an opening. Vietnam adopted a raft of eradication measures in late 2005, including a drive to vaccinate tens of millions of chickens and ducks. Officials also imposed a ban on live markets and poultry farming in cities, tightened regulations on transporting birds, and restricted the raising of ducks and quail, which were thought to be spreading the disease without getting sick themselves. The virus went silent for a time. Vietnam boasted it had cornered the virus. But then it resurfaced, establishing a new beachhead in ducks that had not been properly vaccinated. In 2008 and then again in 2009, poultry outbreaks were reported from the north of the country to the south. After more than two dozen provinces were struck in 2008, Vietnam’s agriculture minister acknowledged that only a few localities were completely capable of controlling the disease and blamed their slow response for the recurring epidemic. His deputy said the country’s poultry vaccination program was flagging. While both poultry outbreaks and human cases were still few relative to 2004 and 2005, FAO officials cautioned that the Vietnamese government would be unable to keep paying for the vaccination drive. Researchers, meantime, noted the separate strains circulating in northern and southern Vietnam were both becoming more lethal.

In China, human infections spiked in early 2009, striking provinces across the breadth of the country. As in earlier years, these cases were occurring without corresponding accounts of poultry outbreaks. WHO officials again concluded that the epidemic among birds was worse than China was reporting and promised, along with FAO, to press their concerns with the Beijing government. “We still have a very serious situation in the agriculture sector,” said Hans Troedsson, who had become WHO’s senior representative in Beijing after leaving Hanoi. “The virus is well-entrenched and circulating in the environment.”

Thailand appeared to fare better. After repeatedly claiming it had banished the bug only to see it return, the Thai government launched an ambitious campaign to crush it in 2005. About seven hundred thousand village health volunteers were mobilized to watch for any hint of emerging infection. Twice a year, the government conducted nationwide door-to-door inspections, dubbed X-ray surveys, searching for infected poultry. Stricken flocks were culled, their owners compensated. Duck grazing was barred. Reported outbreaks tailed off. But researchers continued to detect the virus in bird samples, and suspicions lingered. Were Thai farmers secretly doping their chickens to look healthy? “Some commercial producers in Thailand are apparently using unauthorized vaccines to protect their flocks and vaccinating without proper oversight from health authorities,” FAO’s infectious disease chief wrote in August 2006.

Elsewhere, the virus kept coming back. The disease reappeared in 2008 and 2009 among the birds of Hong Kong, India, Pakistan, and the West African countries of Benin and Togo. In mid-2008, Nigeria reported its first new H5N1 outbreaks in almost a year, in a pair of poultry markets. When scientists tested the virus, they were dismayed to find it was different from those previously circulating in sub-Saharan Africa, a baffling transplant from either Europe or the Middle East. And after nearly a year, a new case surfaced in ducks in Germany. “Somewhat surprising,” German authorities admitted.

The virus was already entrenched in a few places outside East Asia. Egypt officially acknowledged in July 2008 that H5N1 was endemic in its flocks, primarily in the Nile Delta. Bangladesh was equally unable to root out the disease. Domenech called the crises in those two countries “particularly worrying.”

He also offered a chilling admonition for Europe. Tens of millions of apparently healthy ducks and geese that graze along the Danube River and in the wetlands surrounding the Black Sea could be spreading the infection. “It seems,” he said, “a new chapter in the evolution of avian influenza may be unfolding silently in the heart of Europe.”

Even more chilling was the prospect raised by the debut of H1N1 swine flu in early 2009. What would happen when this new arrival spread from its apparent source in North America to countries like Indonesia, China, Vietnam, and Egypt, where bird flu was already endemic? What new virus might emerge from the encounter of these two novel strains? “We must never forget that the H5N1 avian influenza is now firmly established in poultry in several countries,” Margaret Chan told an assembly of the world’s top health officials in May 2009. “No one can say how this avian virus will behave when pressured by large numbers of people infected with the new H1N1 virus.” The swine flu virus had already demonstrated an uncanny ability to swap genes and shift shape. Might this highly contagious strain now acquire the attributes that make avian flu so deadly? Or might swine flu finally provide its avian cousin with the keys required to break loose among people? “Do not drop the ball on monitoring H5N1,” Chan urged Asian health ministers at a separate session in Bangkok called to address swine flu. “We have no idea how H5N1 will behave under the pressure of a pandemic.”