Chinese researchers released a report on a new strain of the bird flu this week, indicating that more than a third of patients infected with it died after being admitted to the hospital.
Called H7N9, the strain first broke out in China in late March. It has affected 130 people and killed 37.
The World Health Organization is calling it "one of the most lethal influenza viruses" ever seen as it spread faster than the last bird flu.
Scientists estimate the death rate to be 36 percent.
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The previous bird flu outbreak was stopped after China closed down numerous live animal markets. They believed that flu to be spread mainly bird-to-human.
A recent article comparing the H7N9 strain to the H5N1 showed that both viruses were mainly related to poultry exposure, as 75% of those infected with the new strain had contact with poultry.
There was not enough evidence to support the claim that H7N9 is spread human-to-human.
Researchers also found that the new strain affects older people more, with the average age of infection being 62 years.
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Men are also more prone to infection than women.
But there is good news in the otherwise bleak-sounding reports. They have found that the numbers of bird flu cases has stalled.
"The good news is that numbers of [H7N9] cases have stalled," Cecile Viboud and Lone Simonsen of the U.S. National Institutes of Health said.
But they do warn that the virus may still "persist" and return in the winter.
And the next time it comes around, it may be more deadly, as it has learned to adapt to previous therapies used to treat it.
Doctors in Shanghai who treated 14 sufferers of H7N9 found it was resistant to Tamiflu in three patients.