Just THREE mutations are needed to make bird flu a potential pandemic strain that could kill millions, experts warn

  •  Flu strain known as H7N9, now mostly infects birds 
  • Has infected at least 779 people in outbreaks in and around China
  • Mutations in three amino acids made the virus more able to bind to human cells
  • However, researchers say the chances of the triple mutation are 'low' 

Scientists have identified three mutations that, if they occurred at the same time in nature, could turn a strain of bird flu now circulating in China into a potential pandemic virus that could spread among people.

The flu strain, known as H7N9, now mostly infects birds but it has infected at least 779 people in outbreaks in and around China, mainly related to poultry markets.

The World Health Organization said earlier this year that all bird flu viruses need constant monitoring, warning that their constantly changing nature makes them 'a persistent and significant threat to public health'.

The three mutations, if they occurred at the same time in nature, could turn a strain of bird flu now circulating in China into a potential pandemic virus.

The three mutations, if they occurred at the same time in nature, could turn a strain of bird flu now circulating in China into a potential pandemic virus.

THE H7N9 STRAIN 

The H7N9 strain currently mostly infects birds but it has infected at least 779 people in outbreaks in and around China, mainly related to poultry markets.

Just this week China said it will shut poultry markets in certain districts of two cities after H7N9 bird flu infections were detected, state media reported on Sunday, the latest incidents in this year's more severe outbreak of the virus.

 Human cases of bird flu have been unusually high for China since last year, with three times more fatalities from H7N9 in the first four months of the year than in all of 2016. 

But deaths fell in April for the third consecutive month.

 

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At the moment, the H7N9 virus does not have the capability to spread sustainably from person to person. But scientists are worried it could at any time mutate into a form that does.

To assess this risk, researchers led by James Paulson of the Scripps Research Institute in California looked at mutations that could potentially take place in the H7N9 virus's genome.

They focused on the H7 hemagglutanin, a protein on the flu virus surface that allows it to latch onto host cells.

The team's findings, published in the journal PLoS Pathogens , showed that in laboratory tests, mutations in three amino acids made the virus more able to bind to human cells - suggesting these changes are key to making the virus more dangerous to people.

Scientists not directly involved in this study said its findings were important, but should not cause immediate alarm.

'This study will help us to monitor the risk posed by bird flu in a more informed way, and increasing our knowledge of which changes in bird flu viruses could be potentially dangerous will be very useful in surveillance,' said Fiona Culley, an expert in respiratory immunology at Imperial College London.

She noted that while 'some of the individual mutations have been seen naturally, ... these combinations of mutations have not', and added: 'The chances of all three occurring together is relatively low.'

Wendy Barclay, a virologist and flu specialist also at Imperial, said the study's findings were important in showing why H7N9 bird flu should be kept under intense surveillance.

'These studies keep H7N9 virus high on the list of viruses we should be concerned about,' she said. 

'The more people infected, the higher the chance that the lethal combination of mutations could occur.'

THE 1918 FLU OUTBREAK - THE WORLD THE WORLD HAS EVER SEEN 

Lacking a reliable cure, public health groups concentrated on prevention 

Lacking a reliable cure, public health groups concentrated on prevention 

The deadly flu virus attacked more than one-third of the world's population, and within months had killed more than 50 million people – three times as many as the World War I – and did it more quickly than any other illness in recorded history.

Most influenza outbreaks disproportionately kill juvenile, elderly, or already weakened patients; in contrast the 1918 pandemic predominantly killed previously healthy young adults.

To maintain morale, wartime censors minimized early reports of illness and mortality in Germany, Britain, France, and the United States.

However, newspapers were free to report the epidemic's effects in Spain, creating a false impression of Spain as being especially hard hit - and leading to the pandemic's nickname Spanish flu.

The close quarters and massive troop movements of World War I hastened the pandemic and probably both increased transmission and augmented mutation, researchers believe.

The global mortality rate from the 1918/1919 pandemic is not known, but an estimated 10% to 20% of those who were infected died, with estimates of the total number of deaths ranging from 50-100 million people.