|MadSci Network: Immunology|
The immunity components involved in protection against influenza are well-known and H5N1 is not so much dangerous to birds as it is to humans. The main risk is that these birds will transmit to pigs the H5N1 strain that is dangerous to humans. Pigs are routinely infected with influenza strains that are also able to infect humans. If a pig is infected with a human strain and a bird strain, the genetic material of both viruses can recombine and form a new virus, with the pathogenic characteristics of avian H5N1 influenza but that is able to infect humans and be transmitted between humans. Note that there has been occurences of bird-to-human transmission but this is rare and mostly happen in repeated close-contact situations. Also, these infections can rarely be transmitted between humans.
The risk of keeping a flock of infected birds in isolation thus far outweigh the benefit of getting rid of it. If one bird escapes or comes in contact with a bird that is not quarantined, the isolation will have been for nothing. Moreover the cost of keeping whole flocks of birds in isolation, with sufficient protection for human caretakers, would be staggering for most low-income countries where these infections now occur.
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