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.”
In the five years after the virus reemerged in mid-2003, it tallied nearly 390 confirmed human cases and 245 confirmed deaths. For each one of those fatalities, almost precisely one million birds either succumbed to the disease or were slaughtered to contain it. That tremendous disparity between human and avian deaths underscores where the action has been. The bulk of the battle has consisted of culling, vaccinating, testing, and protecting poultry with the soldiers drawn from the ranks of the agricultural and veterinary services. The spread of disease among animals has long been beyond the mandate of public health, receiving little of the attention that a menace of such magnitude deserves.
Yet if there is any possibility of postponing future human flu pandemics, whether born of H5N1 or another strain, it means reducing the circulation of these viruses in animals. The less the microbe spreads and replicates, the fewer times the dice are rolled. And the less often the dice are rolled, the longer it will likely take for the virus to mutate or reassort into an epidemic strain.
By contrast, once a pandemic strain emerges and begins passing easily from one person to another, the only hope will be to retard its ineluctable progress by using antiviral drugs, quarantines, and other measures to keep people from mixing. A delay of even a few days would be no mean achievement. This could provide more time to start producing and distributing vaccines. Though they wouldn’t come soon enough for those infected at the beginning of the pandemic, millions of lives could be spared if vaccines arrive in time for those sickened toward the tail end. Yet ultimately, this is a rear-guard action. “You accept a victory as slowing the virus down,” offered Michael Ryan, WHO’s head of epidemic alert and response.
For much of their history, the fields of human and animal health have been divorced and introspective. When bird flu outbreaks were reported across Southeast Asia in early 2004, relations were strained between WHO and its sister agency, the FAO. Though officials on the ground tried at times to craft ad hoc alliances, tensions simmered over turf and money. Since then, these two UN agencies and the independent World Organization for Animal Health have taken steps to enhance cooperation, convening joint strategy sessions and setting up a common early-warning system to share information about bird flu and other diseases. But for many in public health, the fight in the animal kingdom has remained an afterthought.
“I don’t think the medical community has paid enough attention to the veterinary community in terms of the risks for humans,” said veteran scientist Dr. Michael Perdue. “It is the responsibility for human health, for the medical community, to reach out.” Perdue told me that means, for instance, pressing to get money for cash- strapped veterinary counterparts and helping set up more labs for testing animal diseases.
In 2006 Perdue joined the U.S. Department of Health and Human Services, where he took a leading role in preparing the United States for the coming epidemic. By the end of 2008, the department had spent about $1 billion toward creating a stockpile of antiviral drugs sufficient to treat about a quarter of the U.S. population. Another $1.5 billion went toward the development of advanced technologies for making pandemic vaccines, while nearly $1 billion more was invested in setting up a stockpile of prepandemic vaccines, which are based on current H5N1 subtypes and might afford limited protection to medical staff and other vital personnel in the early days of an epidemic. These measures, too, could save millions of lives, though they are powerless to preclude the inevitable.
Perdue, a genial Mississippi native, has a rare perspective on flu. He has hunted it on both sides of the
