News / Health

    Gene Swapping Makes New China Bird Flu a Moving Target

    A girl, who was previously infected with the H7N9 bird flu virus, waves as she is being transferred to a public ward from the ICU at Ditan hospital in Beijing, Apr. 15, 2013.A girl, who was previously infected with the H7N9 bird flu virus, waves as she is being transferred to a public ward from the ICU at Ditan hospital in Beijing, Apr. 15, 2013.
    x
    A girl, who was previously infected with the H7N9 bird flu virus, waves as she is being transferred to a public ward from the ICU at Ditan hospital in Beijing, Apr. 15, 2013.
    A girl, who was previously infected with the H7N9 bird flu virus, waves as she is being transferred to a public ward from the ICU at Ditan hospital in Beijing, Apr. 15, 2013.
    Reuters
    A new bird flu virus that has killed 13 people in China is still evolving, making it hard for scientists to predict how dangerous it might become.
     
    Influenza experts say the H7N9 strain is probably still swapping genes with other strains, seeking to select ones that might make it fitter.

    If it succeeds, the world could be facing the threat of a deadly flu pandemic. But it may also fail and just fizzle out.
     
    The virus' instability also raises questions about whether H7N9 might become resistant to antiviral drugs such as Roche's antiviral drug Tamiflu, a possibility already suggested by analyses of genetic data available on the strain so far.
     
    “Even with just the three [gene] sequences we have available, there's some evidence that one doesn't quite fit with the other two. So we might think this virus is still fishing around for a genetic constellation that its happy with,” said Wendy Barclay, a flu virologist at Imperial College London.
     
    “Maybe there are other viruses out there that it is still exchanging genes with until it gets to a stable constellation.”
     
    To be able to say with any confidence whether this new strain, which before March had never been seen in humans, could go on to cause a pandemic, scientists need to know a lot more.
     
    H7N9 a triple mix bird flu
     
    So far, genetic sequence data from samples from three H7N9 victims and posted on the website of GISAID, the Global Initiative on Sharing All Influenza Data, show the strain is a so-called “triple reassortant” virus with a mixture of genes from three other flu strains found in birds in Asia.
     
    Writing in the New England Journal of Medicine last week, researchers who conducted a detailed analysis of the strain's origin said it seemed that so far the re-assortment of genes to make H7N9 had taken place in birds rather than in humans or in any other mammal - a somewhat reassuring sign.
     
    Barclay said this may continue, and could mean it is some time before the strain finds a form in which it can spread swiftly and efficiently in bird populations.
     
    Yet genetic analyses also show the virus has already acquired some mutations that make it more likely be able to spread between mammals, and more able to spark a human pandemic.
     
    A study in the online journal Eurosurveillance by leading flu experts Yoshihiro Kawaoka of the University of Wisconsin and Masato Tashiro at the National Institute of Infectious Diseases in Tokyo, said the H7N9 sequences “possess several characteristic features of mammalian influenza viruses, which are likely to contribute to their ability to infect humans”.
     
    These features, the scientists wrote, “raise concerns regarding their pandemic potential”.
     
    That sentiment was echoed on Saturday by the World Health Organization (WHO), which said “genetic changes seen among these H7N9 viruses suggesting adaptation to mammals are of concern” and warned: “Further adaptation may occur”.
     
    Pandemic potential

    While experts take some comfort in the lack of evidence so far that H7N9 is passing from person to person - a factor that would dramatically increase its pandemic potential - they are find little comfort in not yet knowing how the 60 or so people confirmed as having this flu strain became infected.
     
    “We know H7 viruses can spill over into humans ... and for me the most important thing to find out now is from which species do we think this H7N9 is spilling over,” said An Osterhaus, head of viroscience of the Erasmus Medical Centre in the Netherlands.
     
    “Is it one species? Are there different species? At this stage we are still lacking a lot of data.”
     
    He said rigorous surveillance of wild birds, such as ducks and quail, and poultry such as chickens, as well as well-known flu-carrying mammals such as pigs, should yield answers.
              
    Recent pandemic viruses - including the H1N1 “swine flu” of 2009/2010 - have been mammal and bird flu mixtures. Experts say these hybrids are more likely to be milder, because mammalian flu tends to make humans less severely ill than bird flu.
     
    Pure bird flu strains - like the new H7N9 strain and like the H5N1 strain that has killed around 371 of 622 the people it has infected since 2003 - are generally more deadly for people.
     
    The world's worst known pandemic, the “Spanish flu” of 1918 that killed more than 50 million people, was a bird flu that had picked up gene mutations that enabled it to spread efficiently in humans.
     
    David Heymann, a flu expert and head of Britain's Chatham House Centre on Global Health Security, said it is important to put the discovery of H7N9 in humans into the context of modern-day scientific capability.
              
    He said that in the years since the outbreak of Severe Acute Respiratory Syndrome (SARS) in China in 2003, there has been a significantly increased focus on detecting and reporting flu-like respiratory infections in Asia and across the world.
     
    The harder scientists look, he said, the more likely they are to find viruses that are potentially threatening but may equally be the sort of events that in the past might have flared up and petered out again under the flu surveillance radar.
     
    That said, he stressed this is no time to relax.
     
    “Influenza viruses are very unstable. And [any] mutation is  a random event - so nobody can predict when it will happen,” he said. “You can't take your eye off anything. You have to keep you eye on everything.”

    You May Like

    Native Americans Ask: What About Our Water Supply?

    They say they have been facing a dangerous water contaminant for decades - uranium – but the problem has received far less attention than water contamination by lead in Flint, Michigan

    Pakistan's President Urges Nation Not to Celebrate Valentine's Day

    Mamnoon Hussain criticizes Valentine's Day, which falls on Sunday this year, as a Western import that threatens to undermine the Islamic values of Pakistan

    Mother of IS Supporter: Son Was Peaceful, 'Role Model'

    Somali-American Abdirizak Mohamed Warsame pleaded guilty Thursday to charges of conspiring to provide material support to Islamic State militants

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Two-thirds of World Faces Water Shortagei
    X
    February 12, 2016 7:31 PM
    Four billion people — or two out of every three on the planet — do not have enough water to meet their basic needs. That is far greater than previously thought, according to a new study that presents a more accurate picture of the problem. As VOA's Rosanne Skirble reports, the findings will help policymakers and the public craft solutions to address the threat.
    Video

    Video Two-thirds of World Faces Water Shortage

    Four billion people — or two out of every three on the planet — do not have enough water to meet their basic needs. That is far greater than previously thought, according to a new study that presents a more accurate picture of the problem. As VOA's Rosanne Skirble reports, the findings will help policymakers and the public craft solutions to address the threat.
    Video

    Video Gateway to Mecca: Historical Old Jeddah

    Local leader Sami Nawar's family has been in the Old City of Jeddah for hundreds of years and takes us on a tour of this ancient route to Mecca, also believed to be the final resting place of Adam's wife, Eve.
    Video

    Video New Technology Aims to Bring Election Transparency to Uganda

    A team of recent graduates from Uganda’s Makerere University has created a mobile application designed to help monitor elections and expose possible rigging. The developers say the app, called E-Poll, will make Uganda's democratic process fairer. From Kampala, VOA's Serginho Roosblad reports.
    Video

    Video As Refugees Perish, Greek Graveyards Fill

    Aid workers on the Greek island of Lesbos say they are struggling to bury the increasing number of bodies of refugees that have been recovered or washed up ashore in recent months.  The graveyards are all full, they say, yet as tens of thousands of people clamor to get out of Syria, it is clear refugees will still be coming in record numbers. For VOA, Hamada Elrasam reports from Lesbos, Greece.
    Video

    Video Russia Bristles at NATO Expansion in E. Europe

    Russian Foreign Minister Sergei Lavrov is meeting Friday with the head of NATO after the Western military alliance and the United States announced plans for the biggest military build-up in Europe since the Cold War. Russia has called NATO's moves a threat to stability in Europe. But NATO says the troop rotations and equipment are aimed at reassuring allies concerned about Russia as VOA's Daniel Schearf reports from Moscow.
    Video

    Video To Fight Zika, Scientists Target Mosquitoes

    Mosquitoes strike again. The Zika virus outbreak is just the latest headline-grabbing epidemic carried by these biting pests, but researchers are fighting back with new ways to control them. VOA's Steve Baragona takes a look.
    Video

    Video Mosul Refugees Talk About Life Under IS

    A top U.S. intelligence official told Congress this week that a planned Iraqi-led operation to re-take the city of Mosul from Islamic State militants is unlikely to take place this year. IS took over the city in June 2014, and for the past year and a half, Mosul residents have been held captive under its rule. VOA's Zana Omar talked to some families who managed to escape. Bronwyn Benito narrates his report.
    Video

    Video Scientists Make Progress Toward Better Diabetes Treatment, Cure

    Scientists at two of the top U.S. universities say they have made significant advances in their quest to find a more efficient treatment for diabetes and eventually a cure. According to the International Diabetes Federation, the disease affects more than 370 million people worldwide. VOA’s George Putic reports.
    Video

    Video NATO to Target Migrant Smugglers

    NATO has announced plans to send warships to the Aegean Sea to target migrant smugglers in the alliance's most direct intervention so far since a wave of people began trying to reach European shores.
    Video

    Video Russia's Catholics, Orthodox Hopeful on Historic Pope-Patriarch Meeting

    Russia's Catholic minority has welcomed an historic first meeting Friday in Cuba between the Pope and the Patriarch of Russia's dominant Orthodox Church. The Orthodox Church split with Rome in 1054 and analysts say politics, both church and state, have been driving the relationship in the centuries since. VOA's Daniel Schearf reports from Moscow.
    Video

    Video Used Books Get a New Life on the Streets of Lagos

    Used booksellers are importing books from abroad and selling them on the streets of Africa's largest city. What‘s popular with readers may surprise you. Chris Stein reports from Lagos.
    Video

    Video After NH Primaries All Eyes on South Carolina

    After Tuesday's primary in New Hampshire, US presidential candidates swiftly turned to the next election coming up in South Carolina. The so-called “first-in-the-South” poll may help further narrow down the field of candidates. Zlatica Hoke reports.
    Video

    Video Smartphone Helps Grow Vegetables

    One day, you may be using your smartphone to grow your vegetables. A Taipei-based company has developed a farm cube — a small, enclosed ecosystem designed to grow plants indoors. The environment inside is automatically adjusted by the cube, but it can also be controlled through an app. VOA's Deborah Block has more on the gardening system.
    Video

    Video Exhibit Turns da Vinci’s Drawings Into Real Objects

    In addition to being a successful artist, Renaissance genius Leonardo da Vinci designed many practical machines, some of which are still in use today, although in different forms. But a number of his projects were never realized — until today. VOA’s George Putic reports.