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

China May Be Biggest Winner From Ukraine Crisis

Missile sales, oil and gas shipments are among many areas that may drive Beijing and Moscow closer together in coming years More

Obama Faces Chaotic World, Limits of Power

Current foreign policy issues bring into focus challenges for US policymakers who are mindful of Americans' waning appetite for overseas military engagements More

SADC Meeting Lesotho Officials to Resolve Stalemate

Official says regional bloc has been engaged with leaders in Lesotho to resolve political disagreement that led to coup attempt More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
West Africa Ebola Vaccine Trials Possible by Early 2015i
X
Carol Pearson
August 30, 2014 7:14 PM
A U.S. health agency is speeding up clinical trials of a possible vaccine against the deadly Ebola virus that so far has killed more than 1,500 people in West Africa. If successful, the next step would be a larger trial in countries where the outbreak is occurring. VOA's Carol Pearson has more.
Video

Video West Africa Ebola Vaccine Trials Possible by Early 2015

A U.S. health agency is speeding up clinical trials of a possible vaccine against the deadly Ebola virus that so far has killed more than 1,500 people in West Africa. If successful, the next step would be a larger trial in countries where the outbreak is occurring. VOA's Carol Pearson has more.
Video

Video Survivors Commemorate 70th Anniversary of Nazi Liquidation of Jewish Ghetto

When the German Nazi army occupied the Polish city of Lodz in 1939, it marked the beginning of a long nightmare for the Jewish community that once made up one third of the population. Roughly 200,000 people were forced into the Lodz Ghetto. Less than 7,000 survived. As VOA’s Kane Farabaugh reports, some survivors gathered at the Union League Club in Chicago on the 70th anniversary of the liquidation of the Lodz Ghetto to remember those who suffered at the hands of the Nazi regime.
Video

Video Cost to Raise Child in US Continues to Rise

The cost of raising a child in the United States continues to rise. In its latest annual report, the U.S. Department of Agriculture says middle income families with a child born in 2013 can expect to spend more than $240,000 before that child turns 18. And sending that child to college more than doubles that amount. VOA’s Deborah Block visited with a couple with one child in Alexandria, Virginia, to learn if the report reflects their lifestyle.
Video

Video Chaotic Afghan Vote Recount Threatens Nation’s Future

Afghanistan’s troubled presidential election continues to be rocked by turmoil as an audit of the ballots drags on. The U.N. says the recount will not be completed before September 10. Observers say repeated disputes and delays are threatening the orderly transfer of power and could have dangerous consequences. VOA correspondent Meredith Buel reports.
Video

Video Ukraine Battles Pro-Russia Rebel Assault

After NATO concluded an emergency meeting to discuss the crisis in eastern Ukraine, the country is struggling to contain heavy fighting near the strategic port of Mariupol, on the Azov Sea. Separatist rebels are trying to capture the city, allegedly with Russian military help, and Ukraine's defense forces are digging in. VOA's Daniel Schearf spoke with analysts about what lies ahead for Ukraine.
Video

Video Growing Business Offers Paint with a Twist of Wine

Two New Orleans area women started a small business seven years ago with one thing in mind: to help their neighbors relieve the stress of coping with a hurricane's aftermath. Today their business, which pairs painting and a little bit of wine, has become one of the fastest growing franchises across the U.S. VOA’s June Soh met the entrepreneurs at their newest franchise location in the Washington suburbs.
Video

Video Ebola Vaccine Trials To Begin Next Week

The National Institutes of Health says it is launching early stage trials of a vaccine to prevent the Ebola virus, which has infected or killed thousands of people across West Africa. The World Health Organization says Ebola could infect more than 20,000 people across the region by the time the outbreak is over. The epidemic has health experts and governments scrambling to prevent more people from becoming infected. Zlatica Hoke has more.
Video

Video Asian Bacteria Threatens Florida Orange Trees

Florida's citrus fruit industry is facing a serious threat from a bacteria carried by the Asian insect called psyllid. The widespread infestation again highlights the danger of transferring non-native species to American soil. VOA’s George Putic reports.
Video

Video Aging Will Reduce Economic Growth Worldwide in Coming Decades

The world is getting older, fast. And as more people retire each year, fewer working-age people will be there to replace them. Bond rating agency Moody’s says that will lead to a decline in household savings; reducing global investments - which in turn, will lead to slower economic growth around the world. But experts say it’s not too late to mitigate the economic impact of the world’s aging populations. Mil Arcega has more.
Video

Video Is West Doing Enough to Tackle Islamic State?

U.S. President Barack Obama has ruled out sending ground troops to Iraq to fight militants of the so-called Islamic State, or ISIS, despite officials in Washington describing the extremist group as the biggest threat the United States has faced in years. Henry Ridgwell reports from London on the growing uncertainty over whether the West’s response to ISIS will be enough to defeat the terrorist threat.
Video

Video Coalition to Fight Islamic State Could Reward Assad

The United States along with European and Mideast allies are considering a broader assault against Islamic State fighters who have spread from Syria into Iraq and risk further destabilizing an already troubled region. But as VOA State Department Correspondent Scott Stearns reports, confronting those militants could end up helping the embattled Syrian President Bashar al-Assad.
Video

Video Made in America Socks Get Toehold in Online Fashion Market

Three young entrepreneurs are hoping to revolutionize the high-end sock industry by introducing all-American creations of their own. And they’re doing most of it the old-fashioned way. VOA’s Julie Taboh recently caught up with them to learn what goes into making their one-of-a-kind socks.
Video

Video Americans, Ex-Pats Send Relief Supplies to West Africa

Health organizations from around the world are sending supplies and specialists to the West African countries that are dealing with the worst Ebola outbreak in history. On a smaller scale, ordinary Americans and African expatriates living in the United States are doing the same. VOA's Carol Pearson reports.

AppleAndroid