A person in North Yorkshire has been diagnosed with a strain of flu similar to a virus circulating in pigs.
It is the first time the virus has been detected in humans in the UK, the UK Health Security Agency (UKHSA) said.
Here is what you need to know.
What is the virus?
The virus is called influenza A(H1N2)v. It is similar to a strain of flu circulating in pigs in the UK.
What do we know about the first case?
A person in North Yorkshire visited their GP with breathing problems.
They were diagnosed with the illness as part of routine national flu surveillance.
It is not known how they caught the virus, and they are not known to have worked with pigs.
They had a mild illness and have now fully recovered.
Close contacts of the case are being followed up by UKHSA and will be offered testing and treatment if they test positive.
Have there been cases in other parts of the world?
Yes and no.
There have been 50 human cases of A(H1N2)v reported globally since 2005.
However, none of them have been this exact strain.
The UKHSA said this is a “distinct clade” which is different to the other human cases reported around the world, but similar to viruses in UK pigs.
An 18-year-old in the US was diagnosed with A(H1N2)v in August after being in contact with pigs at an agricultural fair.
No other cases were reported after that incident, and there was no human-to-human transmission.
Is this swine flu? Bird flu? Both?
This virus is not the same as H1N1, which caused the 2009 swine flu pandemic.
H1N1 contained genetic material from viruses that were circulating in pigs, birds and humans in the 1990s and 2000s.
It is no longer referred to as swine flu, and now circulates seasonally in humans. It is different from the viruses currently circulating in pigs.
A(H1N2)v is a subtype of the influenza A virus. Influenza A viruses circulate in seven different species, including humans, birds and pigs, but normally stay within their species.
Animal influenza viruses are distinct from human influenza viruses and do not easily transmit to and among humans, according to the World Health Organisation.
A(H1N2)v is not linked to birds. The current dominant bird flu strain is H5N1 – of particular concern is the fact it has spread to mammals.
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What happens now?
UKHSA is monitoring the situation closely and plans are under way to step up flu surveillance in parts of North Yorkshire.
The agency is also investigating how the person caught the virus.
The UKHSA has notified the WHO of the latest case.
What should I do if I have symptoms?
The UKHSA’s advice for people with respiratory symptoms remains the same – while you have symptoms you should avoid contact with other people, particularly if they are old or have existing medical conditions.