UK’s Health Security Agency (UKHSA) on Monday confirmed the first human case of rare influenza A (H1N2) virus -- similar to flu viruses currently circulating in pigs in the country. “This is the first detection of this strain of flu in a human in the UK,” the UKHSA said in a statement, noting that it is working closely to determine the characteristics of the pathogen and assess the risk to human health.
There have been a total of 50 human cases of influenza A(H1N2)v reported globally since 2005; none of them related genetically to this strain. Influenza A(H1N2)v has not previously been detected in humans in the UK.
Human infections with swine influenza viruses occur sporadically. Based on early information, the infection detected in the UK is a distinct clade (1b.1.1) -- different from recent human cases of influenza A(H1N2) elsewhere in the world but is similar to viruses in UK swine, the UKHSA said.
H1N2 was detected in the patient, who experienced respiratory symptoms, as part of routine national flu surveillance undertaken by UKHSA and the Royal College of General Practitioners (RCGP). While the patient experienced a mild illness and has fully recovered, the source of the infection has not yet been ascertained and remains under investigation, the agency said.
“It is thanks to routine flu surveillance and genome sequencing that we have been able to detect this virus. This is the first time we have detected this virus in humans in the UK, though it is very similar to viruses that have been detected in pigs,” said Meera Chand, Incident Director at UKHSA, in a statement.
“We are working rapidly to trace close contacts and reduce any potential spread,” she added. The UKHSA advised people with any respiratory symptoms to avoid contact with other people while symptoms persist, particularly if the people they are coming into contact with are elderly or have existing medical conditions.
They also called on pig keepers to report any suspicion of Swine Flu in their herds to their local vet immediately. H1N1, H1N2 and H3N2 are major subtypes of swine influenza A viruses in pigs and occasionally infect humans, usually after direct or indirect exposure to pigs or contaminated environments.
In 2009, there was a pandemic in humans caused by an influenza virus (influenza AH1N1(pdm09)) commonly referred to as ‘Swine Flu’.That virus contained genetic material from viruses that were circulating in pigs, birds and humans in the 1990s and 2000s.
Influenza A H1N1(pdm09) is now circulating in humans seasonally and is no longer referred to as Swine Flu. It is distinct from the viruses currently circulating in pigs.