On the heels of yesterday's blog (see EID Journal: Human Infection with EA Swine-Origin A(H1N1) Virus, the Netherlands, Sept 2019), we have a frustratingly generic report from Denmark's SSI on the recent detection of a novel (presumably swine-variant) flu virus in a resident, albeit without providing any specifics on the subtype.
The SSI describes this novel flu as likely coming from pigs, which suggests an H1Nx, H2Nx, or H3Nx, with H1N1, H2N1, and H3N2 being the most likely subtypes.
But swine are viewed as excellent mixing vessels for human, swine, and avian influenza viruses, and so other combinations are possible (see The Reassortment Tango).
And as we've discussed many times before (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?) - swine flu viruses have a bit of an advantage in the pandemic sweepstakes, as only H1, H2, and H3 influenza subtypes are known to have sparked a human pandemic in the last 130 years.
So far, the good news is that most swine variant viruses haven't become biologically `fit' enough spark a pandemic. In order to be successful, they need to be able to replicate and transmit on par with already circulating human flu viruses.
Less reassuring, surveillance, testing, and reporting on swine variant viruses around the world is haphazard at best, and in many regions, nonexistent.
We will hopefully get more details on this case in the WHO's next Risk Assessment Summary of Influenza at the Human-Animal Interface, but for now this appears to be an isolated case, although the patient reported no recent contact with pigs.
Isolated cases of new influenza virus variant in a citizen
In January, a case of influenza was found in a citizen with a variant that probably originates from pigs.
Last edited 12 February 2021
In January, a case of an influenza virus variant, presumably originating from pigs, was found in a citizen of Denmark. This happened via the national influenza monitoring at the Statens Serum Institut (SSI).
SSI assesses that this is an isolated case, as there have been no signs of further spread of infection.
The citizen lives in the countryside and had underlying disease.
Different from seasonal flu
The citizen had symptoms typical of influenza and covid-19. And during the hospitalization, the citizen was tested positive for influenza virus.
However, upon closer examination of the virus at the National Influenza Center at SSI, it was found that the virus was different from the usual seasonal influenza viruses.
The analyzes showed that this virus variant presumably originates from pigs.
"The citizen has not had contact with pigs himself, and no further cases have been identified in connection with the detection of infection. In the same way, there are no signs of infection in others, including close contacts ", says section manager Ramona Trebbien from SSI.
It has not been possible to identify the source of the infection.
Not previously seen in Denmark
Occasional cases of influenza virus infection between animals and humans have been reported abroad in the past - so-called zoonotic transmission. But no such case has been seen before in Denmark.
"At present, however, we have not found any signs that the virus in question should have a special ability to jump from pigs to humans. There is also no data to suggest that it can be transmitted between people, ”says Ramona Trebbien.
SSI assesses that this has been an isolated case that does not give rise to public health concerns.
