News / Health

Lab-Altered H5N1 Flu More Infectious to Humans than Birds

A staff member works on a blood sample of a chicken at the Veterinary Research Bureau.
A staff member works on a blood sample of a chicken at the Veterinary Research Bureau.
Jessica Berman
A new study suggests a laboratory-mutated H5N1 avian influenza virus could pose a greater risk to humans than to birds, adding to concerns about the new avian flu strain that has emerged recently in China. 

Over a year ago, Japanese researchers created a genetically-altered version of the H5N1 avian influenza virus to explore the risk of human-to-human transmission. They reported in the journal Nature in early 2012 that the mutated pathogen could be transmitted among mammals through the air in aerosol droplets -- for example, from sneezing. They conducted their experiments with ferrets, small domesticated mammals that are a good model for human disease transmission.

The experiment showed that the viral strain has the potential to cause a global human pandemic, even without contact with infected poultry or even person-to-person contact. That finding sparked international security concerns that the pathogen could be used as a biological weapon.  

So far, 600 cases of H5N1 in humans have been reported to the World Health Organization.  The virus causes severe pneumonia and respiratory failure.  The illness has killed 60 percent of those who have contracted it.  

Following up on the Japanese research, an international team studied just how infectious the virus would be to humans, should mutated copies ever jump the species barrier.  

John Skehel is a virologist with the National Institute for Medical Research in London. Writing in the journal Nature, Skehel and co-researchers describe how effectively amino acids from the mutant bird-flu strain are able to bind, or latch onto human cell surface proteins or receptors, as compared with bird or avian cells.

“And we find that it will bind to human receptors about 200 times better than it binds to avian receptors,” Skehel explained.

In other words, humans appear to be at far greater risk than birds of becoming ill with the deadly mutated form of the H5N1 virus.  And even though the mutant virus' grip on human cells is not as strong as that of other infectious flu viruses, it still appears, in the laboratory, to be highly contagious to human cells  -- a finding one researcher described as "confounding."

As scientists continue to learn more about H5N1, international public health officials are also keeping a close watch on another avian flu virus, which the World Health organization is calling one of the most lethal pathogens doctors have ever faced.

Since it was detected this past February, the H7N9 influenza strain has infected more than one hundred people in China, mostly in Shanghai, and killed nearly one-quarter of them.  So far, all human cases appear to have resulted from contact with infected birds, and the new strain has shown no signs of being transmissible from human to human.

Tom Frieden is director of the US Centers for Disease Control and Prevention, or CDC, headquartered in Atlanta, Georgia.

Frieden says H5N1 -- in its natural, unmutated form -- is easy to spot and control because infected flocks become visibly sick.  Not so with H7N9.

“With H5[N1], the birds get sick and the country culls the flock and it stops spreading.  Here, the birds don’t get sick so you can’t cull the flock,” stated Frieden.

Frieden says the CDC, like a number of other international medical research centers, is studying samples of the H7N9 virus it acquired from China. The CDC is working closely with Chinese health officials to develop a vaccine against the new bird flu.

You May Like

Video Americans, Tourists, Reflect on Meaning of Thanksgiving

VOA garnered opinions from several people soon after November 13 Paris attacks, which colored many of their thoughts

Video Thais Send Security Concerns Down the River

In northern Thailand, the annual tradition of constructing floating baskets to carry away the year’s bad spirits highlights the Loy Krathong festival

Video Tree Houses - A Branch of American Dream

Workshops aimed at teaching people how to build tree houses have become widely popular in America in recent years

This forum has been closed.
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Islamic State Unfazed by Losses in Iraq, Syriai
November 26, 2015 5:21 AM
Progress in the U.S.-led effort to beat Islamic State on its home turf in Iraq and Syria has led some to speculate the terror group may be growing desperate. But counterterror officials say that is not the case, and warn the recent spate of terror attacks is merely part of the group’s evolution. VOA National Security correspondent Jeff Seldin has more.

Video Islamic State Unfazed by Losses in Iraq, Syria

Progress in the U.S.-led effort to beat Islamic State on its home turf in Iraq and Syria has led some to speculate the terror group may be growing desperate. But counterterror officials say that is not the case, and warn the recent spate of terror attacks is merely part of the group’s evolution. VOA National Security correspondent Jeff Seldin has more.

Video Taiwan Looks for Role in South China Sea Dispute

The Taiwanese government is one of several that claims territory in the hotly contested South China Sea, but Taipei has long been sidelined in the dispute, overshadowed by China. Now, as the Philippines challenges Beijing’s claims in an international court at The Hague, Taipei is looking to publicly assert its claims. VOA’s Bill Ide has more from Beijing.

Video Syrian Refugees in US Express Concern for Those Left Behind

Syrian immigrants in the United States are concerned about the negative tide of public opinion and the politicians who want to block a U.S. plan to accept 10,000 Syrian refugees. Zlatica Hoke reports many Americans are fighting to dispel suspicions linking refugees to terrorists.

Video After Paris Attacks, France Steps Up Fight Against IS

The November 13 Paris attacks have drawn increased attention to Syria, where many of the suspected perpetrators are said to have received training. French President Francois Hollande is working to build a broad international coalition to defeat Islamic State in Syria and in Iraq. Zlatica Hoke reports.

Video US, Cambodian Navies Pair Up in Gulf of Thailand

The U.S. Navy has deployed one of its newest and most advanced ships to Cambodia to conduct joint training drills in the Gulf of Thailand. Riding hull-to-hull with Cambodian ships, the seamen of the USS Fort Worth are executing joint-training drills that will help build relations in Southeast Asia. David Boyle reports for VOA from Preah Sihanouk province.

Video Americans Sharpen Focus on Terrorism

Washington will be quieter than usual this week due to the Thanksgiving holiday, even as Americans across the nation register heightened concerns over possible terrorist threats. VOA’s Michael Bowman reports new polling data from ABC News and the Washington Post newspaper show an electorate increasingly focused on security issues after the deadly Islamic State attacks in Paris.

Video World Leaders Head to Paris for Climate Deal

Heads of state from nearly 80 countries are heading to Paris (November 30-December 11) to craft a global climate change agreement. The new accord will replace the Kyoto Protocol on Climate Change that expired in 2012.

Video Uncertain Future for Syrian Refugee Resettlement in Illinois

For the trickle of Syrian refugees finding new homes in the Midwest city of Chicago, the call to end resettlement in many U.S. states is adding another dimension to their long journey fleeing war. Organizations working to help them integrate say the backlash since the Paris attacks is both harming and helping their efforts to provide refugees sanctuary. VOA's Kane Farabaugh reports.

Video Creating Physical Virtual Reality With Tiny Drones

As many computer gamers know, virtual reality is a three-dimensional picture, projected inside special googles. It can fool your brain into thinking the computer world is the real world. But If you try to touch it, it’s not there. Now Canadian researchers say it may be possible to create a physical virtual reality using tiny drones. VOA’s George Putic reports.

Video New American Indian Village Takes Visitors Back in Time

There is precious little opportunity to experience what life was like in the United States before its colonization by European settlers. Now, an American Indian village built in a park outside Washington is taking visitors back in time to experience the way of life of America's indigenous people. Carol Pearson narrates this report from VOA's June Soh.

Video Even With Hometown Liberated, Yazidi Refugees Fear Return

While the northern Iraqi town of Sinjar has been liberated from Islamic State forces, it's not clear whether Yazidi residents who fled the militants will now return home. VOA’s Mahmut Bozarslan talked with Yazidis, a religious and ethnic minority, at a Turkish refugee camp in Diyarbakır. Robert Raffaele narrates his report.

Video Nairobi Tailors Make Pope Francis’ Vestments

To ensure the pope is properly attired during his visit, the Kenya Conference of Catholic Bishops asked the Dolly Craft Sewing Project in the Nairobi slum of Kangemi to make the pope's vestments, the garments he will wear during the various ceremonies. Jill Craig reports.

Video Cross-Border Terrorism Puts Europe’s Passport-Free Travel in Doubt

The fallout from the Islamic State terror attacks in Paris has put the future of Europe’s passport-free travel area, known as the "Schengen Zone," in doubt. Several of the perpetrators were known to intelligence agencies, but were not intercepted. Henry Ridgwell reports from London European ministers are to hold an emergency meeting Friday in Brussels to look at ways of improving security.

Video El Niño Brings Unexpected Fish From Mexico to California

Fish in an unexpected spectrum of sizes, shapes and colors are moving north, through El Niño's warm currents from Mexican waters to the Pacific Ocean off California’s coast. El Nino is the periodic warming of the eastern and central Pacific Ocean. As Faiza Elmasry tells us, this phenomenon thrills scientists and gives anglers the chance of a once-in-a-lifetime big catch. Faith Lapidus narrates.

Video Terrorism in Many Forms Continues to Plague Africa

While the world's attention is on Paris in the wake of Friday night's deadly attacks, terrorism from various sides remains a looming threat in many African countries. Nigerian cities have been targeted this week by attacks many believe were staged by the violent Islamist group Boko Haram. In addition, residents in many regions are forced to flee their homes as they are terrorized by armed militias. Zlatica Hoke reports.

Video Study: Underage Marriage Rate Higher for Females in Pakistan

While attitudes about the societal role of females in Pakistan are evolving, research by child advocacy group Plan International suggests that underage marriage of girls remains a particularly big issue in the country. VOA’s Ayesha Tanzeem reports how such marriages leads to further social problems.

VOA Blogs