H7N9
The World Health Organization (WHO) has said that this virus is "unusually dangerous".
In June 2014, WHO indicated that so far there had been 450 laboratory-confirmed cases of H7N9, including 165 deaths.
There is also evidence that this type of avian flu can be passed from person to person but this is rare.
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H7N7
In 2003, an outbreak in a chicken farm in The Netherlands spread to nearly 800 poultry farms and resulted in the culling of almost 11 million chickens.
The virus infected up to 90 people and killed one man.
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H10N8
Only detected in China in 2013.
Researchers say it does not pose an imminent global threat.
There have been three reported cases and two deaths since December 2013.
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H10N7
Reported for the first time in humans in 2004 when two children became ill in Egypt.
The symptoms were relatively mild and both children recovered.
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H7N3
An outbreak in 2004 led to the culling of millions of birds in Canada but only two mild human infections were confirmed.