Scientists have reported the first case of human-to-human transmission of the new strain of bird flu that has emerged in China.
The British Medical Journal said a 32-year-old woman was infected after caring for her father. Both later died.
Until now there had been no evidence of anyone catching the H7N9 virus other than after direct contact with birds.
But experts stressed it does not mean the virus has developed the ability to spread easily between humans.
By 30 June there had been 133 cases of H7N9 bird flu reported in eastern China and 43 deaths.
Most people had visited live poultry markets or had close contact with live poultry in the week or two before they became ill.
Yet researchers found that the 32-year-old woman had become infected in March after caring for her 60-year-old father in hospital.
Scientists have reported the first case of human-to-human transmission of the new strain of bird flu that has emerged in China
Unlike her father – who had visited a poultry market in the week before falling ill – she had no known exposure to live poultry but fell ill six days after her last contact with him.
Both died in intensive care of multiple organ failure.
Tests on the virus taken from both patients showed the strains were almost genetically identical, which supports the theory that the daughter was infected directly from her father rather than another source.
Public health officials tested 43 close contacts of the patients but all tested negative for H7N9, suggesting the ability of the virus to spread was limited.
The researchers said that while there was no evidence to suggest the virus had gained the ability to spread from person to person efficiently, this was the first case of a “probable transmission” from human to human.
“Our findings reinforce that the novel virus possesses the potential for pandemic spread,” they concluded.
Dr. James Rudge, of the London School of Hygiene and Tropical Medicine, said that limited transmission between humans is not surprising and has been seen before in other bird flu viruses, such as H5N1.
He added: “It would be a worry if we start to see longer chains of transmission between people, when one person infects someone else, who in turn infects more people, and so on.
“And particularly if each infected case goes on to infect, on average, more than one other person, this would be a strong warning sign that we might be in the early stages of an epidemic.”
An accompanying editorial in the BMJ, co-authored by Dr. James Rudge, concluded that while this study might not suggest that H7N9 is any closer to delivering the next pandemic, “it does provide a timely reminder of the need to remain extremely vigilant”.
Six people died in China since the outbreak of a new strain of bird flu and health experts there are scrambling to contain the spread of H7N9 virus.
How deadly is it? The new strain of bird flu has killed six out of the 16 people diagnosed with H7N9 virus – mostly older adults and young children. Sufferers demonstrate flu-like symptoms such as fever, runny nose, and an itchy throat. So far none of those infected have spread the virus on to another human. And three of the most recent cases involved men, according to The Washington Post.
Bird flu victims include a 38-year-old from Zhejiang province, in eastern China, who became sick March 7; a 64-year-old, also from Zhejiang, who became ill March 28; and a 48-year-old from Shanghai who also became sick March 28.
Six people died in China since the outbreak of a new strain of bird flu
Where did the virus originate? Shanghai officials traced the new strain back to a pigeon sold at the Huhai agricultural market, which was closed Thursday. Now, Chinese health authorities are monitoring some 400 people who were in contact with the people infected. Officials are monitoring this group in case, by some chance, the virus does mutate to the point that it can be passed by humans – and also to more quickly diagnose any of the 400 people if they begin to exhibit symptoms.
What makes the virus so dangerous? Its speed. “If a flock of chickens or ducks get H5N1, it will kill them and set off alarm bells,” John Oxford, a professor of virology at Queen Mary, University of London, Queen Mary, told theTimes.
“But this virus seems to be a bit more tricky.” The influenza strain spreads quickly through large groups of birds, which often don’t display symptoms. As a result, the disease can be incredibly difficult to track.
“At this stage it’s still unlikely to become a pandemic,” Richard Webby, director of a WHO flu center at St Jude Children’s Research hospital in Memphis, Tennessee, told The Guardian.
“We should be concerned, there are no alarm bells ringing yet.”
What’s being done to stop it? Health officials have already slaughtered more than 20,000 birds as a precautionary measure. Shanghai is closing all of its live poultry markets beginning Saturday, and US health authorities are working on a vaccine. The outbreak is rekindling memories of the SARS outbreak that began in China 10 years ago, which infected 8,000 people worldwide largely due to Beijing’s tendency to keep secrets. This time, however, Chinese health authorities have largely done a commendable job keeping the public on alert.
“It was the Ministry of Health and Family Planning that first came to us and volunteered the information,” said Gregory Hartl, a spokesman for the WHO in Geneva.
Controversial research into making bird flu easier to spread in people is to resume after a year-long pause.
Some argue the research is essential for understanding how viruses spread and could be used to prevent deadly pandemics killing millions of people.
Research was stopped amid fierce debate including concerns about modified viruses escaping the laboratory or being used for terrorism.
The moratorium gave authorities time to fully assess the safety of the studies.
A type of bird flu known as H5N1 is deadly and has killed about half the people who have been infected.
It has not caused millions of deaths around the world because it lacks the ability to spread from one person to another. Cases tend to come from close contact with infected birds.
Scientists at the Erasmus University in the Netherlands and the University of Wisconsin-Madison in the US discovered it would take between five and nine mutations in the virus’ genetic code to allow it to start a deadly pandemic.
Their research was the beginning of a long-running furor involving scientists, governments and publishers of scientific research.
The US National Science Advisory Board for Biosecurity asked academic journals not to publish key parts of the findings. It was concerned terrorists would use the details to develop a biological weapon.
It provoked outcry among some scientists who said their academic freedom was being restricted. Other scientists said the risk of the virus spreading was too great for such research to take place and described it as a folly.
Controversial research into making bird flu easier to spread in people is to resume after a year-long pause
The details were eventually published in the journals Nature and Science.
However, the academics involved agreed to a voluntary 60-day moratorium on research – which was later extended to more than a year.
It was to give governments time to review safety standards needed in laboratories to conduct research with enhanced viruses and whether they wanted to fund such research.
A letter signed by 40 virus researchers around the world, published in the journals Science and Nature, said the moratorium was being lifted.
It said appropriate conditions had been set in most of the world and their studies were “essential for pandemic preparedness”.
One of the leading proponents of the research Prof. Ron Fouchier, from the Erasmus Medical Centre, said it had been “frustrating” to shut down research for the year.
“This research is urgent, while we are having this pause bird flu virus continues to evolve in nature and we need to continue this research.
“We cannot wait for another year or two years.”
He expects to restart his laboratory’s work within the next couple of weeks.
However, it is a different case for many of the other research groups involved. The US has not decided on the conditions that it will allow the experiments to take place and the same applies to US-funded research taking place in other countries.
The decision has continued debate on whether the research should take place at all.