Skip to main content

From ducks to chickens to deadly virus

By Nathan Wolfe and Oliver Pybus, Special to CNN
updated 2:44 PM EDT, Wed August 21, 2013
STORY HIGHLIGHTS
  • Authors: New study traces origin of flu virus that kills a third of victims
  • They say it shows the need for vigilance and prevention measures vs. flu
  • Ducks could help create the next flu pandemic, need careful monitoring, they say
  • Authors: There's a growing arsenal of tools that will be useful in prevention

Editor's note: Nathan Wolfe is Founder & CEO of Metabiota, a company addressing global infectious disease risk, & the Lorry I. Lokey Consulting Professor of Human Biology at Stanford University. Follow him on Twitter: @virushunter. Oliver Pybus is a Professor at the University of Oxford and a Consulting Senior Scientist at Metabiota and a co-author of a new study in Nature that reports the discovery of the origins of the H7N9 influenza virus.

(CNN) -- Influenza is a little like poker. Only when it wins, we lose.

When a new variant of influenza emerges, it starts with the viral equivalent of a poker hand made up of eight genetic segments. Like getting a four of diamonds or a queen of spades, H7N9 was effectively dealt a seven of Hemagluttinin (the H) and a nine of Neuraminadase (the N). Along with the genes on its other six segments, the H and N determine whether a new virus has the capability to spread in the global human population, the epidemiological equivalent of winning a championship pot.

A new report today sheds light on the origins of H7N9. The virus, which jumps from chickens to humans, has killed around a third of the 134 known human cases since it was identified in April. H7N9 has also shown some capacity to spread from person to person. It has rightly put the global health community on alert.

Nathan Wolfe
Nathan Wolfe
Oliver Pybus
Oliver Pybus

Today's report shows that H7N9 came about through repeated shuffling of influenza viruses present in wild birds and domestic ducks and chickens. It also documents the existence of a previously unidentified virus spreading in chickens.

The new virus, an H7N7, shares much in common with H7N9. And experiments on ferrets, the standard mammal model for influenza, suggest that like H7N9 it may have the capacity to infect humans. This means that undiscovered human cases of the H7N7 may exist, and with additional shuffles and further mutation this virus's offspring could also represent a global health concern.

In today's world the fight against epidemics like influenza overwhelmingly involves chasing the viruses that have already begun to spread in people. The argument is that given all of the potential viruses and mutations that could lead to the next big one, attempting to predict or prevent it is a fool's errand. It's increasingly clear that argument is wrong.

Influenza epidemics are anything but random. The origins of H7N9 and H7N7 tell a specific story of transmission from wild birds to ducks and eventually chickens and people.

Because chickens are so numerous -- at 19 billion their numbers dwarf other domestic animals -- and commonly sold live in some places, viruses that can spread efficiently in our favorite consumable bird increase their opportunity to make that fateful jump into people. And because wild birds, the ultimate origin of all influenza viruses, share close connections with domestic ducks, from whom the H and N genes jumped, these ducks become an important stepping stone for new viruses.

Even what's absent in the viruses' genes themselves tell us something useful. The N genes in both the new H7N9 and H7N7 viruses contain remarkably similar deletions of genetic material -- modifications not seen in their duck virus ancestors. The independent occurrence of such deletions strongly suggests that the deleted region is critical to proliferation in chickens.

While still emerging, the story of H7N9 and H7N7 suggest highly practical recommendations. Ducks could help create the next pandemic influenza, so monitor them closely and consider ways to keep them separate from wild birds and other domestic animals.

As humans working alongside domestic birds will likely be hit first, monitor these sentinel populations, particularly in regions with novel types of avian influenza. Track the genetic geography of influenza during the process of its emergence as it moves between locations and wild and domestic animal hosts, because some genes will have a higher chance of successfully spilling over.

Together these steps will permit us to monitor the viruses we have most to fear from and optimize control measures, like the usefully deployed, but costly, closure of poultry markets.

Increasingly these recommendations are being heeded. The study released today represents part of a larger global effort to take stock of the viruses that can infect us, to document where they reside and to catch them when they spill over.

Governments, academic institutions, nonprofits and even a fledgling but rapidly growing private sector are working together in an unprecedented way to address a problem that increasingly threatens our globally interconnected world.

Together with our Chinese colleagues at the Guangdong Institute of Public Health, for example, we work to monitor new influenza and other viruses among people working in markets and other environments in precisely the regions where these viruses are emerging. The work represents a partnership with USAID's Emerging Pandemic Threats Predict program, which supports these and other similar activities throughout the viral hotspots of the world.

The work is just beginning. Together with novel digital tools like monitoring internet search patterns and social media for signs of new epidemics, we are adding to a growing arsenal of approaches to catch epidemics and stop them before they become pandemics. In an increasingly interconnected world, where new epidemic threats surround us, it is time we elevate prediction and prevention of epidemics to a central element of global health.

A poker player may not be able to predict exactly when a royal flush will appear, but whoever is counting the cards and tracking the hands will always win in the end.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

The opinions expressed in this commentary are solely those of the authors.

ADVERTISEMENT
Part of complete coverage on
updated 8:21 AM EDT, Mon September 1, 2014
Carlos Moreno says atheists, a sizable fraction of Americans, deserve representation in Congress.
updated 12:25 PM EDT, Sun August 31, 2014
Julian Zelizer says Democrats and unions have a long history of mutual support that's on the decline. But in a time of income inequality they need each other more than ever
updated 12:23 AM EDT, Sun August 31, 2014
William McRaven
Peter Bergen says Admiral William McRaven leaves the military with a legacy of strategic thinking about special operations
updated 12:11 PM EDT, Fri August 29, 2014
Leon Aron says the U.S. and Europe can help get Russia out of Ukraine by helping Ukraine win its just war, sharing defense technologies and intelligence
updated 1:24 PM EDT, Fri August 29, 2014
Timothy Stanley the report on widespread child abuse in a British town reveals an institutional betrayal by police, social services and politicians. Negligent officials must face justice
updated 9:06 PM EDT, Fri August 29, 2014
Peter Bergen and David Sterman say a new video of an American suicide bomber shows how Turkey's militant networks are key to jihadists' movement into Syria and Iraq. Turkey must stem the flow
updated 11:54 AM EDT, Mon September 1, 2014
Whitney Barkley says many for-profit colleges deceive students, charge exorbitant tuitions and make false promises
updated 10:34 AM EDT, Fri August 29, 2014
Mark O'Mara says the time has come to decide whether we really want police empowered to shoot those they believe are 'fleeing felons'
updated 10:32 AM EDT, Thu August 28, 2014
Bill Frelick says a tool of rights workers is 'naming and shaming,' ensuring accountability for human rights crimes in conflicts. But what if wrongdoers know no shame?
updated 10:43 PM EDT, Thu August 28, 2014
Jay Parini says, no, a little girl shouldn't fire an Uzi, but none of should have easy access to guns: The Second Amendment was not written to give us such a 'right,' no matter what the NRA says
updated 1:22 PM EDT, Sat August 30, 2014
Terra Ziporyn Snider says many adolescents suffer chronic sleep deprivation, which can indeed lead to safety problems. Would starting school an hour later be so wrong?
updated 9:30 AM EDT, Fri August 29, 2014
Peggy Drexler says after all the celebrity divorces, it's tempting to ask the question. But there are still considerable benefits to getting hitched
updated 2:49 PM EDT, Fri August 29, 2014
The death of Douglas McAuthur McCain, the first American killed fighting for ISIS, highlights the pull of Syria's war for Western jihadists, writes Peter Bergen.
updated 6:42 PM EDT, Tue August 26, 2014
Former ambassador to Syria Robert Ford says the West should be helping moderates in the Syrian armed opposition end the al-Assad regime and form a government to focus on driving ISIS out
updated 9:21 AM EDT, Wed August 27, 2014
Ruben Navarrette says a great country does not deport thousands of vulnerable, unaccompanied minors who fled in fear for their lives
updated 9:19 AM EDT, Wed August 27, 2014
Robert McIntyre says Congress is the culprit for letting Burger King pay lower taxes after merging with Tim Hortons.
updated 7:35 PM EDT, Tue August 26, 2014
Wesley Clark says the U.S. can offer support to its Islamic friends in the region most threatened by ISIS, but it can't fight their war
updated 4:53 PM EDT, Tue August 26, 2014
America's painful struggle with racism has often brought great satisfaction to the country's rivals, critics, and foes. The killing of Michael Brown and its tumultuous aftermath has been a bonanza.
updated 3:19 PM EDT, Tue August 26, 2014
Rick Martin says the death of Robin Williams brought back memories of his own battle facing down depression as a young man
updated 11:58 AM EDT, Tue August 26, 2014
David Perry asks: What's the best way for police officers to handle people with psychiatric disabilities?
updated 3:50 PM EDT, Mon August 25, 2014
Julian Zelizer says it's not crazy to think Mitt Romney would be able to end up at the top of the GOP ticket in 2016
updated 4:52 PM EDT, Mon August 25, 2014
Roxanne Jones and her girlfriends would cheer from the sidelines for the boys playing Little League. But they really wanted to play. Now Mo'ne Davis shows the world that girls really can throw.
updated 5:04 PM EDT, Mon August 25, 2014
Kimberly Norwood is a black mom who lives in an affluent neighborhood not far from Ferguson, but she has the same fears for her children as people in that troubled town do
updated 5:45 PM EDT, Fri August 22, 2014
It apparently has worked for France, say Peter Bergen and Emily Schneider, but carries uncomfortable risks. When it comes to kidnappings, nations face grim options.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT