UPDATED: 1500hrs
Henry Niman has posted this afternoon that after further review, he believes this report to be a badly translated repost of a story from December on 10 Cases in the United States we already knew about.
Today’s story is ambiguous enough to make that a plausible explanation. Unless and until we can get some confirmation of this story I would advise that you view the following report with caution.
# 6131
This morning Editor & Senior Moderator Tetano on FluTrackers has picked up a series of news articles coming out of Vietnam talking about 10 human cases of infection by a `new’ H3N2 swine flu virus.
Two of these articles are machine translated from Vietnamese, and are therefore a bit garbled, but the third is an English Language report from the VOV (Voice of Vietnam).
Assuming the major points of today’s report are correct (not always a given), there is not enough information provided to know how this virus compares to the A/H3N2v virus which has been detected in a handful of cases in the United States (see CDC Releases Updated H3N2v Interim Guidance).
Keeping the usual caveats in mind regarding early media reports, here is the story from the Voice of Vietnam.
New strain of swine flu detected
Updated : 5:16 PM, 09/02/2012
(VOV) - The Heath Ministry has quoted sources from the Ho Chi Minh City Pasteur Institute confirming that a new kind of porcine flu virus, A/H3N1, has appeared, apparently a combination of the pig-related A/H1N1 and A/H3N2 flu viruses.
The medical sector has monitored 10 patients infected with the A/H3N2 virus with porcine origin, and found that three of them had not had direct contact with any diseased pigs.
Therefore, the sector has not ruled out the possibility of a mutation in the A/H3N2 strain which could lead to transmission between humans, instead of strictly from pigs to humans as previously.
However, the situation has not reached an alarming level because the virus has not changed much; it has low toxicity and has shown no sign of drug resistance.
Flu vaccines are able to cope with small changes in this kind of virus, said Le Hoang San, Vice Director of the HCMC Pasteur Institute.
Swine are highly susceptible to the influenza virus, and are capable of serving as `mixing vessels’, allowing them to reassort into new hybrid strains.
Reassortment happens when two different influenza viruses co-infect the same host, swap genetic material, and produce a hybrid virus.
That is essentially what happened in 2009, when the H1N1 swine flu virus emerged after bouncing around swine herds for a decade or more, picking up genetic changes along the way.
And not surprisingly, this recently emergent `humanized’ H1N1 virus has re-entered the swine population and is once again mixing and matching with other circulating swine flu viruses.
As a result we now have a Swine H3N2 virus that has reassorted with the 2009 pandemic H1N1 virus, producing a new hybrid that has – in a limited fashion – begun to emerge into the human population.
The article above calls the Vietnamese strain a `combination of the pig-related A/H1N1 and A/H3N2 flu viruses’ – which if we take literally – suggests a different reassortment than the one we’ve seen in the United States.
As stories in the media often gloss over or confuse crucial scientific details we really need to wait for a more definitive report before we can talk about the origin, genetic makeup, and potential of this new virus.
For now, this is simply something new to keep an eye on in the ever changing and always surprising world of influenza.
Update: In a conversation with Sharon Sanders of FluTrackers this morning, she pointed out that this article refers to this new reassortant virus as H3N1 (once) and H3N2 (twice).
I took the first mention (H3N1) as a likely misprint, but until we can get some clarification, I don’t think we can say with any confidence exactly which strain this new virus is.
