# 3409
When two different flu viruses infect the same host at the same time – and both viruses infect the same cell simultaneously – they can swap genetic material and create a new `offspring’ virus.
This is what is known as reassortment, and it is how new strains of influenza often are created. The novel H1N1 virus that has created our pandemic is a product of multiple reassortments.
The concern that many scientists have is that at some point the highly contagious – but relatively mild - H1N1 virus will meet up with the hard to transmit – but very deadly – H5N1 bird flu and generate a reassortment.
Of course, you could get lucky and end up with a virus that is both mild and hard to transmit . . . but that isn’t the only possibility.
Today we get a report on these concerns, particularly out of Indonesia, where the bird flu fatality rate is the highest of anywhere in the world.
Comments included are from Dr. C.A. Nidom, no stranger to readers of this blog, who is head of the Avian Influenza lab at Airlangga University in Surabaya and Indonesian Health Minister Supari.
Could swine flu mix with bird flu to create even deadlier strain?
Monday, June 29th 2009, 1:48 PM
Tumbelaka/Getty
A hospital staff locks the gate at Sanglah hospital in Denpasar, Bali. Recent cases of H1N1 flu have raised concerns in Asian countries where H5N1 flu, or avian flu, is already entrenched.
What happens when flus collide?
Indonesia’s first cases of the new H1N1 flu, known as swine flu, have raised concerns that if the virus spreads it could combine with the entrenched and deadly H5N1 avian influenza to create a more lethal strain of flu.
Indonesian Health Minister Siti Fadillah Supari, who confirmed six new H1N1 cases on Sunday, said she was concerned about H1N1, widely known as swine flu, "marrying" with H5N1 avian flu.
Influenza viruses not only mutate quickly and unpredictably, but they can swap genes,especially if a person or animal becomes infected with two strains at once. The new H1N1 strain is itself a mixture of various strains, genetic tests show.
Even if this worst-case scenario did not occur, experts say populous, developing countries such as Indonesia, India or Egypt, where healthcare systems can be rudimentary, will suffer more deaths from the new virus.
This graphic from the FAO shows how two different avian viruses (H10N7 and H7N3) can meet up in a cell and produce a new virus, in this case H7N7.
Any host capable of catching both parent influenzas can become an incubator, or mixing vessel, for a reassortment. Pigs are thought to be particularly good hosts for this sort of mix and matching, although birds, humans, and other mammals are also potential vessels.
Pigs can catch human, avian, and swine influenzas.
How likely any of this is to happen is unknown.
We know it does happen, from time to time, because we can clearly see the results. But it obviously doesn’t happen often.
Otherwise we’d be neck deep in new viruses all the time.
The H5N1 virus has most certainly had opportunities to reassort with seasonal H1N1, along with other flu viruses, and to our knowledge, it hasn’t yet.
That doesn’t mean it can’t or it won’t, but it does suggest there are a lot of factors at play here . . . many of which we don’t completely understand.
That said, reassortment is a legitimate concern, and something that scientists are constantly on the lookout for.
