Why is it taking so long to figure out which AI subtypes were in the Canadian samples?

A story from the Canadian press here.

Here is a snippet:

Teasing out flu viruses found in ducks taking longer than expected: officials

Helen Branswell, CP

Wednesday, November 16, 2005

TORONTO (CP) - It's proving harder than anticipated to type the avian flu viruses wild ducks sampled in Canada were carrying because a number were co-infected with several strains, creating a viral "soup" that is difficult to separate down to its basic ingredients, government officials have admitted.

They say, however, that it appears that none of the viruses are highly pathogenic, a finding that would support the suggestion none of the birds were carrying the worrisome Asian H5N1 flu virus, which is a so-called high path virus.

Damien