News / Science & Technology

Study Identifies Risks of Human Spread of H7N9 Bird Flu

Authorities are taking samples of live poultry from mainland China to test for the H7N9 virus, April 11, 2013.
Authorities are taking samples of live poultry from mainland China to test for the H7N9 virus, April 11, 2013.
Jessica Berman
A new study finds that the recently discovered H7N9 bird flu virus, which has been circulating among poultry flocks in eastern China, can be transmitted among ferrets, small mammals that provide a laboratory model for human contagion.  Since the H7N9 virus was first identified in China last February, there have been 132 human infections confirmed in China and one in Taiwan, with a total of 36 deaths.  While there have been concerns that this bird flu could become a global pandemic, the new study suggests that the virus could spread among people.

So far, it appears that people who have been diagnosed with the H7N9 virus have all had close contact with infected birds, primarily in live poultry markets.  To become a pandemic, the avian virus would have to spread easily from human-to-human.

To find out how efficiently the virus can be transmitted among humans, an international team of researchers, led by Chinese scientists, studied its contagion among ferrets. The small mammals can transmit infectious diseases through aerosols produced by sneezing and coughing, much like humans.

Richard Webby is a virologist at St. Jude Children’s Research Hospital in Memphis, Tennessee and a study co-author.  Webby said the work seems to suggest humans would have to be in close contact to transmit this virus. “That’s what our ferret studies would support. That potentially, if you have infected people very close to uninfected people, you might get transmission," he explained. "But it’s not very efficient.”

Chinese investigators swabbed the noses of a group of ferrets infected with the H7N9 virus taken from an infected human patient who had died. Researchers detected evidence of H7 through the nasal samples before the animals developed respiratory symptoms, suggesting more people may be carriers of the virus than is currently believed.  

The disease was also transmitted to uninfected ferrets through direct contact with infected animals in the same cage, simulating what might happen among human family members living in the same home.

But when they were placed in a separate cage and exposed to diseased animals in another enclosure, only 1 of 3 healthy ferrets contracted H7N9.  Researchers also found the virus did not transmit to pigs, another potential reservoir of influenza.

Experts believe both airborne and direct contact transmission is needed to ignite a pandemic.
 
Anthony Fauci is director of the US National Institute of Allergy and Infectious Diseases.  Fauci said the findings of the Chinese study confirm what's already known about H7N9. "That it can be transmitted to mammals rarely and inefficiently, and it's not being transmitted in any way from person to person," he stated.

Meanwhile, in the first human population study of H7N9 influenza, researchers analyzed just over 1,700 blood samples for 5 different avian flu viruses in the H7 subtype, in both urban and rural areas in southern Vietnam, which neighbors China.  

Investigators found low levels of H7 antibodies, markers of the human immune system's ability to defend against pathogens. The researchers say the low levels suggest that international measures to contain the H7N9 influenza, in the event of severe outbreak, will need to be targeted in Asia.

The Chinese transmissibility study recommends that to avoid H7N9 becoming endemic in poultry populations -- a development that would create new opportuinities for human transmission, live poultry markets in the region must be more carefully and strictly managed.

Their research is published in the journal Science Express.

You May Like

Ukraine: Mysterious 'Roaming Tank' Reportedly Takes Aim at Smugglers

Ukraine's TV, print media, Facebook abuzz with reports a 'roaming tank' is on the loose, destroying vehicles of those involved in smuggling More

US Wildlife Service Begins Probe of Killing of Cecil the Lion

Minnesota man accused of killing beast is in hiding, has been asked to contact US officials; White House to review extradition petition More

Video Kerry Five-Nation Tour to Cover Security, Iran Nuclear Deal

Secretary of state will visit Egypt, Qatar, Singapore, Malaysia, Vietnam to discuss security issues, Iran nuclear deal, Trans-Pacific Partnership More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Booming London Property a ‘Haven for Dirty Money’i
X
July 29, 2015 9:34 PM
Billions of dollars of so-called ‘dirty money’ from the proceeds of crime - especially from Russia - are being laundered through the London property market, according to anti-corruption activists. As Henry Ridgwell reports from the British capital, the government has pledged to crack down on the practice.
Video

Video Booming London Property a ‘Haven for Dirty Money’

Billions of dollars of so-called ‘dirty money’ from the proceeds of crime - especially from Russia - are being laundered through the London property market, according to anti-corruption activists. As Henry Ridgwell reports from the British capital, the government has pledged to crack down on the practice.
Video

Video Hometown of Boy Scouts of America Founder Reacts to Gay Leader Decision

Ottawa, Illinois, is the hometown of W.D. Boyce, who founded the Boy Scouts of America in 1910. In Ottawa, where Scouting remains an important part of the legacy of the community, the end of the organization's ban on openly gay adult leaders was seen as inevitable. VOA's Kane Farabaugh reports.
Video

Video 'Metal Muscles' Flex a New Bionic Hand

Artificial limbs, including the most complex of them – the human hand – are getting more life-like and useful due to constant advances in tiny hydraulic, pneumatic and electric motors called actuators. But now, as VOA’s George Putic reports, scientists in Germany say the future of the prosthetic hand may lie not in motors but in wires that can ‘remember’ their shape.
Video

Video Russia Accused of Abusing Interpol to Pursue Opponents

A British pro-democracy group has accused Russia of abusing the global law enforcement agency Interpol by requesting the arrest and extradition of political opponents. A new report by the group notes such requests can mean the accused are unable to travel and are often unable to open bank accounts. VOA's Henry Ridgwell reports.
Video

Video 'Positive Atmosphere' Points Toward TPP Trade Deal in Hawaii

Talks on a major new trade agreement among 12 Pacific Rim nations are said to be nearing completion in Hawaii. Some trade experts say the "positive atmosphere" at the discussions could mean a deal is within reach, but there is still hard bargaining to be done over many issues and products, including U.S. drugs and Japanese rice. VOA's Jim Randle reports.
Video

Video Genome Initiative Urgently Moves to Freeze DNA Before Species Go Extinct

Earth is in the midst of its sixth mass extinction. The last such event was caused by an asteroid 66 million years ago. It killed off the dinosaurs and practically everything else. So scientists are in a race against time to classify the estimated 11 million species alive today. So far only 2 million are described by science, and researchers are worried many will disappear before they even have a name. VOA’s Rosanne Skirble reports.
Video

Video Scientists: One-Dose Malaria Cure is Possible

Scientists have long been trying to develop an effective protection and cure for malaria - one of the deadliest diseases that affects people in tropical areas, especially children. As the World Health Organization announces plans to begin clinical trials of a promising new vaccine, scientists in South Africa report that they too are at an important threshold. George Putic reports, they are testing a compound that could be a single-dose cure for malaria.
Video

Video 'New York' Magazine Features 35 Cosby Accusers

The latest issue of 'New York' magazine features 35 women who say they were drugged and raped by film and television celebrity Bill Cosby. The women are aged from 44 to 80 and come from different walks of life and races. The magazine interviewed each of them separately, but Zlatica Hoke reports their stories are similar.
Video

Video US Calls Fight Against Human Trafficking a Must Win

The United States is promising not to give up its fight against what Secretary of State John Kerry calls the “scourge” of modern slavery. Officials released the country’s annual human trafficking report Monday – a report that’s being met with some criticism. VOA’s National Security correspondent Jeff Seldin has more from the State Department.
Video

Video Washington DC Underground Streetcar Station to Become Arts Venue

Abandoned more than 50 years ago, the underground streetcar station in Washington D.C.’s historic DuPont Circle district is about to be reborn. The plan calls for turning the spacious underground platforms - once meant to be a transportation hub, - into a unique space for art exhibitions, presentations, concerts and even a film set. Roman Mamonov has more from beneath the streets of the U.S. capital. Joy Wagner narrates his report.
Video

Video Europe’s Twin Crises Collide in Greece as Migrant Numbers Soar

Greece has replaced Italy as the main gateway for migrants into Europe, with more than 100,000 arrivals in the first six months of 2015. Many want to move further into Europe and escape Greece’s economic crisis, but they face widespread dangers on the journey overland through the Balkans. VOA's Henry Ridgwell reports.
Video

Video Stink Intensifies as Lebanon’s Trash Crisis Continues

After the closure of a major rubbish dump a week ago, the streets of Beirut are filling up with trash. Having failed to draw up a plan B, politicians are struggling to deal with the problem. John Owens has more for VOA from Beirut.
Video

Video Paris Rolls Out Blueprint to Fight Climate Change

A U.N. climate conference in December aims to produce an ambitious agreement to fight heat-trapping greenhouse gases. But many local governments are not waiting, and have drafted their own climate action plans. That’s the case with Paris — which is getting special attention, since it’s hosting the climate summit. Lisa Bryant takes a look for VOA at the transformation of the French capital into an eco-city.
Video

Video Racially Diverse Spider-Man Takes Center Stage

Whether it’s in a comic book or on the big screen, fans have always known the man behind the Spider-Man mask as Peter Parker. But that is changing, at least in the comic book world. Marvel Comics announced that a character called Miles Morales will replace Peter Parker as Spider-Man in a new comic book series. He is half Latino, half African American, and he is quite popular among comic book fans. Correspondent Elizabeth Lee reports from Los Angeles.
Video

Video Historic Symbol Is Theme of Vibrant New Show

A new exhibit in Washington is paying tribute to the American flag with a wide and eclectic selection of artwork that uses the historic symbol as its central theme. VOA’s Julie Taboh was at the DC Chamber of Commerce for the show’s opening.

VOA Blogs