The UK has confirmed its first human case of a new strain of swine flu, and health officials are working to pinpoint the virus’s source.
On Monday, the UK Health Security Agency (UKHSA) announced that an individual tested positive for Influenza A H1N2v, a variant related to the flu viruses affecting pigs in the country.
Preliminary data reveals that the H1N2 infection in the UK differs genetically from recent human cases worldwide, characterized by its clade, 1b.1.1.
“We are working swiftly to trace close contacts and mitigate any potential spread,” said UKHSA’s incident director, Meera Chand, according to reports.
Once the patient in North Yorkshire began showing respiratory symptoms, their doctor tested them for the flu on November 9 as part of routine nationwide flu surveillance. Subsequent genome sequencing and PCR testing confirmed H1N2.
While specific details about the patient’s age and overall health remain undisclosed, it is known that the individual experienced a mild illness and has since fully recovered.
Swine flu outbreaks, caused by type A flu viruses, are common in pigs, with occasional human infections occurring as a result.
Variant flu viruses are typically influenza viruses that circulate among specific animal populations, such as birds, horses, or pigs, and sporadically infect humans, as per the Centers for Disease Control and Prevention (CDC).
Human infections with Influenza A subtypes, H1N1v, H3N2v, and H1N2v, have been identified in the past, with the most recent US human cases reported in August, according to the CDC.
Although H1N2v has not previously been detected in humans in the UK, the UKHSA notes that 50 human cases have been reported globally since 2005.
Virologist Ian Brown, from the UK’s Animal and Plant Health Agency, explained: “These viruses generally lack the ability to spread human to human, and such events are usually explained by direct or indirect contact with pigs.”
While swine flu viruses can potentially cause widespread illness in pig populations, they typically result in minimal fatalities. Infected pigs may exhibit mild or no respiratory symptoms at all.
The case does not call for alarm, experts assert, although further details about the strain are necessary to assess the risk.
University of Glasgow molecular virologist Ed Hutchinson warns that influenza A viruses can occasionally establish themselves in new host species.
“Human and animal influenza A viruses can ‘breed’ if they get into the same host, producing hybrid offspring that are well-adapted to growing in humans but which aren’t recognized by our immune responses to previous human influenza infections or vaccinations (a process called genetic shift),” he explained.
Strains of influenza A subtype H1N1 have been responsible for numerous outbreaks, including the 2009 swine flu pandemic. Human infections with the virus spread rapidly across the globe in weeks.
The strain, A(H1N1)pdm09, now circulates seasonally in humans and is no longer termed swine flu, differing from the viruses currently circulating in pigs.
To prevent the spread of flu viruses between pigs and humans, the CDC recommends hand-washing before and after contact with pigs, avoiding eating or drinking around them, and staying away from pigs showing signs of illness.
Health authorities in the UK are reaching out to close contacts of the confirmed case and advising on necessary actions.
For individuals experiencing respiratory symptoms, the UKHSA advises that they should avoid contact with others, particularly the elderly or those with existing medical conditions.
