East Anglia's pig farmers have been put on biosecurity alert following the UK's first human infection from a new strain of swine flu.

The UK Health Security Agency (UKHSA) has confirmed a human case of influenza A(H1N2)v in North Yorkshire - a virus similar to flu currently circulating in pigs. 

It was detected as part of routine national flu surveillance undertaken by UKHSA and the Royal College of General Practitioners (RCGP). The individual was tested by their GP after experiencing respiratory symptoms, and has now fully recovered after a "mild illness".

Experts are now "working rapidly" to trace contacts, to find out how the individual became infected and "assess the risk to human health".

Health officials said flu infections passing from animals to humans do occur "occasionally" - usually after "direct or indirect exposure to pigs or contaminated environments".

So pig farmers have been warned of the importance of biosecurity to safeguard animals and workers in a crucial East Anglian farm sector, with an estimated 20pc of the national herd kept in Norfolk and Suffolk.

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. 

"Pig keepers must also report any suspicion of swine flu in their herds to their local vet immediately."

That message was echoed by National Pig Association (NPA) chief executive Lizzie Wilson, who said: "Pig keepers should be vigilant to any signs of ill health amongst their animals and maintain high levels of hygiene and biosecurity when working with pigs."

She added: "There is no evidence there is any risk to humans from either handling or eating pork. The UKHSA is investigating how this virus strain was contracted by a human and we await their conclusions."

The NPA says there has been a "marked increase" in reports of swine flu in pigs in recent months, but infected animals usually recover in five to seven days.

There have been a total of 50 human cases of influenza A(H1N2)v reported globally since 2005, but none related genetically to this strain. 

In 2009, there was a human pandemic caused by a different strain of swine flu, but the UKHSA said that virus is now circulating in humans seasonally and is no longer referred to as swine flu.