CDC: Revised Interim Recommendations for Prevention, Monitoring, and Public Health Investigations of HPAI H5

 

#18,513

Nine months ago, in CDC: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations Of HPAI H5N1 In Animals, the CDC released initial guidance due to the increased risk from recently discovered HPAI in American dairy cattle. 

Since then - as the threat has expanded beyond just occupational exposure to dairy cows - this guidance has been updated as needed. 

In early November, following the discovery of asymptomatic H5N1 infections in some farmworkers - the CDC released Multiple revised H5N1 Guidance Documents, geared to farm workers, their employers, clinicians, public health officials, and the general public.

These documents continue to be revised as new information becomes available, with the 7,900 word guidance document HPAI A(H5N1) Virus: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations  getting a number of changes on Dec 26th.

Finding those changes can be difficult. Some are simply word changes, or minor additions/deletions, while others are far more substantial. 

Using text comparison software, I've isolated the most pertinent changes below, which mostly deal with testing and chemoprophylaxis. The Nov 8th version (retrieved using the Wayback machine) is on the left and the updated Dec 26th version is on the right. 

You can either zoom in on the graphic, or right click and open each image in a new window/tab, and then enlarge it to better read the text.

While these changes are primarily of interest to public health officials or clinicians, they also illustrate how quickly things are changing with regards to the escalating avian flu threat.  

A year ago, the United States had only reported 1 human H5 infection.  Today, officially, there have been 66 this year.  Add in the `probable' cases, and those detected via serological testing, and the number is > 80. 

Not only has HPAI H5 been detected in cattle, it has turned up in goats, alpacas, house cats, mice, and pigs in the United States.  Recently, we saw evidence of it in Mongolian horses.  

The B3.13 `bovine' genotype which affects cattle has been joined by a new, and aggressive D1.1 genotype, which has caused at least 2 severe illnesses in North Americans, and has shown signs of mammalian adaptation.  

Where H5Nx goes in 2025 is unknowable - but if the past year is any indication - we should expect more than a few surprises along the way.