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.
TEXT SIZE - +
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

Video Pope Francis Hopes Dual Canonizations Will Reconcile Church

John the XXIII and John Paul II will be made saints in a ceremony at St. Peter’s Square on April 27 More

Thailand Reacts to Plots Targeting Israelis

Authorities hope arrest of two Lebanese suspects will disrupt plot to attack young Israeli tourists More

Video In Capturing Nature's Majesty, Film Makes Case for Its Survival

'Once Upon a Forest' takes viewers deep into heart of tropical rainforest More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Pope Francis Hopes Dual Canonizations Will Reconcile Churchi
|| 0:00:00
...
 
🔇
X
Jerome Socolovsky
April 22, 2014 4:14 PM
On April 27, two popes - John the XXIII and John Paul II - will be made saints in a ceremony at St. Peter’s Square. VOA religion correspondent Jerome Socolovsky says the dual canonization is part of the current pope’s program to reconcile liberals and conservatives in the Roman Catholic Church.
Video

Video Pope Francis Hopes Dual Canonizations Will Reconcile Church

On April 27, two popes - John the XXIII and John Paul II - will be made saints in a ceremony at St. Peter’s Square. VOA religion correspondent Jerome Socolovsky says the dual canonization is part of the current pope’s program to reconcile liberals and conservatives in the Roman Catholic Church.
Video

Video In Capturing Nature's Majesty, Film Makes Case for Its Survival

French filmmaker Luc Jacquet won worldwide acclaim for his 2005 Academy Award-winning documentary "March of the Penguins". Now Jacquet is back with a new film that takes movie-goers deep into the heart of a tropical rainforest - not only to celebrate its grandeur, but to make the case for its survival. VOA's Rosanne Skirble reports.
Video

Video Boston Marathon Bittersweet for Many Runners

Monday's running of the Boston Marathon was bittersweet for many of the 36,000 participants as they finished the run that was interrupted by a double bombing last year. Many gathered along the route paid respect to the four people killed as a result of two bombings near the finish line. VOA's Carolyn Presutti returned to Boston this year to follow two runners, forever changed because of the crimes.
Video

Video Pacific Rim Trade Deal Proves Elusive

With the U.S.-led war in Iraq ended and American military involvement in Afghanistan winding down, President Barack Obama has sought to pivot the country's foreign policy focus towards Asia. One aspect of that pivot is the negotiation of a free-trade agreement among 12 Pacific Rim nations. But as Obama leaves this week on a trip to four Asian countries he has found it very difficult to complete the trade pact. VOA's Ken Bredemeier has more from Washington.
Video

Video Robotic Mission Kicks Up Lunar Dust

A robotic mission to the moon was deliberately crashed onto the lunar surface late last week, but not before scientists had collected data gathered by the spacecraft which was designed to self-destruct. VOA's Rosanne Skirble reports on the preliminary findings of the craft, called LADEE - an acronym for Lunar Atmosphere and Dust Environment Explorer.
Video

Video Boko Haram Claims Responsibility for Bombing in Nigerian Capital

The Nigerian militant group known as Boko Haram has claimed responsibility for a bombing in the capital on April 14th that killed 75 people. In the video message, Abubakar Shekau, the man who says he ordered the bombing, says nothing about the mass abduction of more than 100 teenage girls, most of whom are still missing. Heather Murdock has more for VOA from Abuja.
Video

Video Ukraine Developments Hang Over Obama Trip to Asia

President Barack Obama's trip to Asia this week comes as concerns over Beijing's territorial ambitions are growing in the region. Those concerns have been compounded by Russia's recent actions in Ukraine and the possibility that Chinese strategists might be looking to Crimea as a model for its territorial disputes with its neighbors. VOA's Bill Ide has more from Beijing.
Video

Video Autistic Adults Face Housing, Job Challenges

Many parents of children with disabilities fear for the future of their adult child. It can be difficult to find services to help adults with disabilities - physical, mental or emotional - find work or live on their own. The mother of an autistic boy set up a foundation to advocate for the estimated 1.2 million American adults with autism, a developmental disorder that causes communication difficulties and often social difficulties. VOA's Faiza Elmasry reports.
AppleAndroid