H2H-H5N1 spread in US

Late yesterday the CDC announced the confirmation of the (previously known) 5th and an additional 6th human H5 infection from the poultry farm in Weld County, Colorado.  This brings the total number of H5 infections in the United States since March of this year to 10.

This report comes on the heels of the report of a second large poultry farm in Weld County testing positive for H5N1 (see CIDRAP report H5N1 strikes another large layer farm in Colorado), and on the eve of the start of the Weld Country Fair (Jul 20th-29th).

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We continue to get more reassurance than details from federal agencies, although it is unclear how much of that is due to difficulties getting information and/or cooperation from local entities.  

Genetic sequences continue to be deposited belatedly, and are often missing critical meta-data (see GISAID comment below), making independent analysis difficult. 

This collection includes many virus sequences from dairy cows, but also closely related viruses detected in poultry and wild birds and in mice, cats and other mammals as well as the recent human infections. Although metadata such as sampling date and location are unfortunately missing from recent datasets, the available data allow a close watch on mutations that may arise as a consequence of virus adaptation to new hosts.

Unknown is how the bovine B3.13 genotype has managed to spillover into poultry, and whether it is now spreading via wild birds.  

Other than reporting that PPE use by poultry workers was `not optimal' (blamed on excessive heat and fans inside barns), we've seen little in the way of epidemiological data (not even onset dates) on these cases.  

For now, HPAI H5N1 appears to lack the ability to spark a human pandemic, but that happy state of affairs could literally change overnight. Unfortunately, we continue to treat HPAI as more of an economic or political problem, than a true public health concern. 

A risky strategy that may work in the short term, but has the potential to end very badly. 

Had anyone dared predict last March - that in 4 months time - we'd have roughly 160 cattle herds infected with H5N1 across 13 states (an underestimate), that we'd be battling large mid-summer outbreaks of H5N1 in commercial poultry, and that we'd have chalked up 10 human cases in the U.S., they'd have been called an alarmist.