It is the first time this strain has been detected in the UK and close contacts are now being traced.
The A(H1N2)v case was detected after a routine test at a GP surgery was analysed in a lab.
The person affected had respiratory symptoms, a mild illness and has now fully recovered.
Investigations are under way into the source of the infection.
Human infections with swine flu viruses do occur – there have been 50 cases of A(H1N2)v reported globally in the past 20 years.
There was a case reported in the United States in August.
The infection found in the UK is slightly different from recent human cases of swine flu globally, health officials say, but similar to viruses in UK pigs.
In 2009, there was a pandemic of swine flu in humans caused by a virus spreading in pigs, birds and humans.
The UK Health Security Agency said it planned to increase surveillance through GP surgeries and hospitals in parts of North Yorkshire where the case was detected.
Meera Chand, the agency’s incident director, said: “We are working rapidly to trace close contacts and reduce any potential spread.
“In accordance with established protocols, investigations are under way to learn how the individual acquired the infection and to assess whether there are any further associated cases.”
People with flu-like symptoms are advised to avoid contact with others, particularly those who are elderly or vulnerable, with other health conditions.
Chief Veterinary Officer Christine Middlemiss said: “We know that some diseases of animals can be transferred to humans – which is why high standards of animal health, welfare and biosecurity are so important.”
She said pig-owners must report any signs of swine flu in their herds to their local vet. (BBC)
