Saturday, October 17, 2009

That Touch Of Mink Flu



# 3845



Today, a bit of an unusual story out of Denmark, where mink at least 11 farms in the Holstebro are reported to be infected with a variant of the human H3N2 virus.


Mink have been known to be infected by influenza strains in the past, although generally by avian or porcine strains.  


In 1984, a rather large outbreak in Swedish mink farms was found to be due to the H10N4 avian virus.  This summary from the Archives of Virology.


An avian influenza A virus killing a mammalian species — the mink

Received: 26 August 1985  Accepted: 26 August 1985 

Summary  During October of 1984 an influenza epidemic occurred on mink farms in the coastal region of South Sweden. Six strains of an influenza A virus were isolated. All six isolates were of the H10 subtype in combination with N4. The H10 subtype in combination with various N subtypes was hitherto only known to occur in avian strains, the prototype being the A/chicken/Germany/N/49 (H10N7) virus.


In 2006, a mink was discovered to have highly pathogenic H5N1 `bird flu’ in Sweden.   This report from CIDRAP news.


Mink had H5 flu virus

In Europe this week, an H5 virus has been confirmed in a new species, a mink found in Sweden. There have been no confirmed reports of H5N1 avian flu in mink, according to a species list maintained by the US Geological Survey's National Wildlife Health Center.


The mink had an aggressive H5 virus and was euthanized, the National Veterinary Institute in Sweden said, as reported by Reuters Mar 27. The animal was found in the Blekinge region of southern Sweden, where several infected birds have been found.


The institute said the mink was thought to have contracted the virus by consuming infected wild birds, the suspected mode of transmission to felines as well.


And more recently, a discovery of H3N2  Swine Influenza in mink in Canada resulted in this report which appeared earlier this year in the Journal of Clinical Microbiology.


Characterization of a Canadian Mink H3N2 Influenza A Virus Isolate Genetically Related to Triple Reassortant Swine Influenza Virus.

Journal of clinical microbiology. 2009 Mar;47(3):796-9.

In 2007, an H3N2 influenza A virus was isolated from Canadian mink. This virus was found to be phylogenetically related to a triple reassortant influenza virus which emerged in Canadian swine in 2005, but it is antigenically distinct.


The transmission of the virus from swine to mink seems to have occurred following the feeding of animals with a ration composed of uncooked meat by-products of swine obtained from slaughterhouse facilities. Serological analyses suggest that the mink influenza virus does not circulate in the swine population.


Presently, the prevalence of influenza virus in Canadian farmed and wild mink populations is unknown. The natural occurrence of influenza virus infection in mink with the presence of clinical signs is a rare event that deserves to be reported.



Anytime a human flu jumps species, as is alluded to in the article below, scientists take notice.  For now, this appears to be more of a scientific curiosity than a public health threat. 


The transmission of the virus has only been detected from human-to mink, and not back again. But that could easily change.


The article below was found, translated, and posted by Commonground on FluTrackers earlier today. 


There is an ongoing thread, with additional articles posted by other newshounds, following developments.  I will obviously be keeping an eye on this thread as well.



Warning on mink influenza

Af: Lars Henrik Aagaard,

16/10/2009 22:30

Mink at least eleven farms in Holstebro area are infected with the new form of human influenza virus. The situation recalls the start of the current H1N1 pandemic in Mexico.


Danish veterinary and health authorities have issued a warning after the mink at least 11 mink farms in Holstebro area in a globally unique occurrence was infected with a new form of human influenza virus.


"It is a situation that creates some concern because we can see that the virus originates in humans. Against this background, we conclude that there is an increased risk that it also can infect back to people, "says senior scientist Poul Henrik Jorgensen, National Veterinary Institute.


The situation has therefore administrations large attention, because it has clear parallels to the current pandemic H1N1 influenza that occurred in Mexico in the spring - probably on the basis of infection with a mutated human influenza viruses from pigs to humans.


"Yes, there is a fairly clear analogy to H1N1. The only major difference is that we fortunately have not seen that the infection is gone the other way? from mink to humans, "says the leader of the influenza laboratory at Statens Serum Institut, Dr. Lars P. Nielsen, who in recent days has conducted detailed analysis of influenza virus from Danish mink.


The analysis conducted on Veteinærinstituttet and Statens Serum Institute shows that the virus has clear resemblance to a type of H3N2 flu that circulated in the Danish population of approximately four years ago.


"It recalls the virus infected people in 2005, but it is altered or mutated a little bit over it. But since in its original version has been circulating in the population for a long time, so we expect that there is some cross-immunity, which means that most will be at least partially protected against it, "says Lars P. Nielsen.


He stresses that the Serum Institute in the period ahead will pay extra attention to possibly submit samples of H3N2 virus from infected humans.


The superintendent's investigation also shows that the antiviral agent Tamiflu, also recommended preventive against H1N1 influenza, with high probability is effective against the new type of H3N2 influenza.


WHO informed

Lars P. Nielsen is Denmark's flu-contact in relation to World Health Organization. In this context, he states that the WHO has been informed of the unique Danish situation and that we then ask the Danish authorities to remain observant and karaterisere virus further.


There is seems to be talking about the first recorded case ever in the world of human influenza infection among mink.

"We do not know how the virus entered the farm, and we get it may never be solved. But it is probably a single factor, because there is a geographically limited area. It may be via food or through an individual who has his time here on the mink farms, "says Poul Henrik Jørgensen from DTU Vetrinærinstituttet.