posted on Oct, 4 2007 @ 01:37 PM
As with most Anti-viral medication regimens there is always a risk of viral resistance both environmentally and biologically. One thing that comes to
mind, especially with H5N1, is that because it is a subtype of Influenza A Virus it has an extremely high rate of virulence. The mutation rates of
any Influenza strain (or any RNA based virus for that matter) are just below the rates of mutation for HIV, which is well known for this.
Specifically when we look at H5, or the 5th Protein of Hemagglutinin, we see that even single changes in the amino acids can alter the virus enough to
create somewhat of a resistance. On the same hand the 1st protein of Neuraminidase, N1, can change the structure of proteins found on the viral
envelope and capsid to become resistant to several anti-viral medications including Tamiflu. With this evidence, it does become clear that
environmental contamination through Tamiflu found in excrement could be a possible concern with cross species transmission.
Having said that there are several factors that need to be examined with Tamiflu ecotoxicology, and unfortunately I am unaware of any true scientific
evidence relating to this issue. There has been some research done into Relenza (the UK equivalent of Tamiflu) which showed some positives in that it
is water soluable and chemically stable, meaning that hydrolysis is not likely to deplete the chemicals, and thus not become mineralized. Other
evidence suggests that Relenza is not able to bind with soil sediments, which would lend some credence to the fact that Tamiflu contamination has
never been observed.