Potential human-to-human transmission of swine flu detected in Yorkshire

The first person in the UK to be diagnosed with a new variant of swine flu may have passed it onto other people, the UK Health Security Agency has said.

An individual over the age of 75 living in North Yorkshire was confirmed to have the Influenza A(H1N2)v virus last month. The person suffered flu-like symptoms and has since fully recovered.

All of their close contacts were tested and none of those results were positive.

But a rapid technical assessment by the UKHSA reveals that two people who came into contact with the individual, including one in their household, suffered symptoms and that “some limited degree of human-to-human transmission may have occurred”.

Both recovered from their symptoms before they could be tested for the swine flu variant.

The UKHSA assessment says that because two contacts experienced symptoms, and as no direct link can be made between the case and local pig farms, limited person-to-person transmission may have taken place.

It says: “There is no virologically confirmed human-to-human transmission.

“The human case viral genome is closely related to circulating viruses in pigs (‘moderate confidence’) and the mutational profile where it can be interpreted is consistent with a hypothesis of recent emergence (‘low confidence’).

“The presence of a case without direct contact with animals, and the presence of a symptomatic household contact, mean that some limited degree of human-to-human transmission may have occurred (‘low confidence’).

“No onwards transmission has been detected through PCR testing of contacts (‘low confidence’; given the normal surveillance lag time in identifying the influenza variant, most testing was relatively late compared to potential exposure and serological assessment is in process and may change this assessment).”

An investigation was carried out by the UKHSA in collaboration with the Animal and Plant Health Agency and Defra, the Francis Crick Institute, local NHS partners and the local authority.

The infected individual lives near to pig farms, a veterinary facility and a live auction market but “no direct link or chain of transmission could be identified between the case and any animal”.

Tests are being carried out at local farms to detect any traces of the variant.

Blood tests of people potentially infected is also being conducted, while enhanced surveillance testing is being carried out in the community, GP surgeries and at the local hospital.

The UKHSA is extending its monitoring of human/animal influenza to a pilot sample of pig farms.

The case was first identified through lab testing on 23 November, but the person had presented to their local GP surgery two weeks earlier.

The UKHSA said “rapid work has been underway to learn more about the virus and its characteristics, including how it may have been acquired and whether it may have spread”.

UKHSA Incident Director Dr Meera Chand said: “This is the first time we have detected this virus in humans in the UK. Since the virus was confirmed we have been working rapidly to learn more about it and how it might have been acquired.

“Investigations to date have not identified any further human cases and sporadic cases of influenza from swine viruses are known to occur.

“The identification of this case highlights the importance of our flu surveillance and genomic sequencing in helping us to identify and learn more about new viruses.”