Quote:
Originally Posted by pranab
Transmission of the Virus * Not all the flue virus have same transmission properties The virus causing Avain Flue spreads by Faeco-oral route
* Human contracting this condition acquire it as a result of contact with infected poultry either by air borne spread or their faeces or or contamination during their food preperation
* people typically acquire flue by inhaling the virus or by being direct contact with respiratory tract secreation of people who are infected
* Healthy adults shed virus 1 day before onset of symptoms and continue to shed for 5-7 days or more. Children shed longer and immunocompromised people till longer....
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I'm not sure of the point of this post but I can elaborate a bit on the current infectivity of H5N1 which isn't exactly clear here.
Poultry and other bird species have disseminated influenza virus when they have H5N1 infection. The virus can be found in most if not all tissues. Therefore the bird droppings do indeed contain virus as does the blood and meat.
The human activities that resulted in infection involved slaughtering the birds without protection, drinking raw duck blood and other forms of consuming uncooked parts, and entering the chicken coop such as kids do to retrieve eggs. These activities result in exposure to high viral loads which is what it currently takes to get infected.
The human cells which the H5N1 virus is more efficient in are in the lower respiratory tract. Human flu is very efficient in upper respiratory tract. So current human infections are not producing large viral loads when those infected cough and exhale.
However, there are now a number of different and still lethal strains of H5N1 circulating. They are referred to as clades and sub-clades. So far, none of the genetic changes appear to be at the location on the H5N1 RNA where it is expected to result in more efficient replication in human upper airway cells. Additional research though has shown that for current human influenza strains, genetic drift goes on for some time before a new strain emerges.
So we remain in a holding pattern. There is no certainly the virus will or will not emerge as a human pandemic. I certainly haven't breathed any sighs of relief. I think it is easy for people to think that because it hasn't happened yet it isn't going to.
Unfortunately, the situation has worsened a tad in the last few weeks. While the cases of new outbreaks among birds had subsided, new outbreaks have occurred again in a wide area covering countries
from Egypt to Nigeria to S Korea including more human cases an another death.
The fact this disease has only killed 155 (one more died 12/24) people should not lead one to think the preparation is excessive. You will wish it had been excessive and realize it wasn't even adequate if H5N1 is the next influenza pandemic that occurs.
22-December-2006, 09:07 PM
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