#18,188
Overnight GISAID released an update showing the latest HPAI sample submitted by the CDC - collected from a farm worker in Colorado on 2024-07-11 (EPI_ISL_19263923) - clusters squarely among the bovine B3.13 H5N1 cases reported since last March in American dairy cattle.
This is significant because this sample appears (based on the date) to come from the cluster of poultry-farm workers who tested positive last week. The last cattle-linked human case announced (also from Colorado) was reported on July 3rd, and on July 12th the CDC stated that sequencing was unsuccessful.
Although we've seen some evidence of spillover of this bovine B3.13 genotype from cattle to other species (see Emergence and interstate spread of highly pathogenic avian influenza A(H5N1) in dairy cattle), reports have been limited and until now we've not seen poultry workers affected.
A month ago, in Highly Pathogenic Avian Influenza H5N1 Genotype B3.13 in Dairy Cattle: National Epidemiologic Brief, the USDA/APHIS reported there was no evidence that wild birds were spreading the B3.13 genotype (but it couldn't be ruled out):
If (and its still a big `if') the bovine B3.13 genotype - which carries several mammalian adaptations - is now spreading in birds, it could make it much harder to eradicate or control.
While we await further details, overnight several experts weighed in on Twitter/X, including Raj Rajnarayanan @RajlabN Assistant Dean of Research and Associate Professor, NYITCOM at Arkansas State University:
And virologist Tom Peacock @PeacockFlu:
Obviously, getting sequences from the infected poultry and from wild birds in Weld County, Colorado would go a long ways towards answering these questions. Hopefully those will be forthcoming sooner rather than later.
Stay tuned.
