Extending the hot zone is not a surprise, although it takes some effort to extract from media reports and official web sites the info on who knew what when
discuss.agonist.org
The spread of the infection outside of the surveillance zone (more than 15 km from the original outbreak) was probably suggested last week. Last Monday media reports indicated that the 7th farm was outside of the 15 km surveillance zone, but the media reports kept mentioning the 5 km hot zone. At the time H7N3 tests were called inconclusive and the possibility of New Castle Disease (NCD) had been raised. However, NCD is a reportable disease and the last report of NCD in Canada was 1973, so the chance that the birds were dying of NCD instead of H7N3 was very low.
Moreover, the slaughterhouse was also located outside of the surveillance region, so it seemed that last week sick birds were shipped to this location increasing the chance of widespread infections (I am not sure of the size of the slaughterhouse, but there is also a processing plant at the same address so I suspect that spread from the location could be significant since they handled a wide assortment of birds, including wild birds, chickens and ducks).
This site not only is outside of the 15 km surveillance region, it is a few km from the Abottsford airport and the US border, increasing the chances of export of H7N3 out of Canada.
The distribution of the 18 confirmed farms further suggests that infections were due to movement of livestock and people in the Fraser Valley, so the chance of spread beyond the 18 confirmed farms is high (since the two farms outside of the surveillance zone were infected last week or earlier and restrictions on farms outside of the surveillance region were not as strict - and at least one farm was sending infected birds to slaughter).
Now further delays are projected as an action plan is discussed. It seems that a good deal of effort has been placed on controlling the available information rather than the virus (which doesn't read press releases), so the ever increasing spread of the infections should not be a surprise. |
