H5N1/flu (other types)

Yesterday PAHO (Pan American Health Organization), in conjunction with the WHO, released a public health risk assessment on the zoonotic spread of H5N1 in the Americas.  These types of assessments - while they can be useful - are only as good as the data used to make them. 

And unfortunately, surveillance and reporting continues to erode, both in the United States, and around the globe (see No News Is . . . Now Commonplace). 

Yesterday we learned that Oklahoma had become the 13th state to detect HPAI H5 in dairy cows, but this was based on samples collected last April, and only recently submitted to the USDA for testing. 

Testing of livestock remains largely voluntary (except for interstate transport of cattle), and no one really knows how widespread the virus is in cattle across the nation. 

Just over 18 months ago, in Flying Blind In The Viral Storm, we looked at the increasing willingness of many countries to delay, downplay, or hide reports of emerging infectious disease events, and it is arguably even more pervasive today. 

The overall risk in the general population of this event for the Region of the Americas to human health is classified as “Low” with a level of confidence in the available information of “Moderate”, for the following reasons:

Epidemiological and virological factors: 

Current epidemiological data indicate localized occurrences of avian influenza A(H5N1) clade 2.3.4.4b in dairy cattle herds within the United States of America, with spillover into humans and other mammals in direct contact. Virologically, the virus remains predominantly bound to avian-type receptors, limiting its transmissibility to humans via respiratory droplets or fomites, as demonstrated by recent studies. A substantial component of the risk of spread throughout the Region of Americas has, and will continue to be, predominantly from wild birds however, after introduction in cattle, the continuous transmission between the different states in the United States has evidenced other mechanisms of transmission (e.g., movement of cattle). Even with no further change in the virus there are likely to be additional outbreaks in mammals, and sporadic cases reported in humans. The recent global risk, given the same parameters, has been considered to be low by the World Health Organization (WHO), but requiring vigilance and ongoing monitoring (1-3).

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But, as the WHO warns: their ability to assess the risks is compromised by limited surveillance.

So while the risks are currently deemed to be `low', we can't afford to be lulled into complacency.  

The CDC has posted the following statement - which confirms much of what we learned earlier today from the State of Colorado - on the (now 4) confirmed human H5 infections among poultry workers from Weld County. 

A fifth presumed positive case will likely be confirmed later today. 

There are still no details provided on whether the workers wore PPEs, or have received antivirals, both of which should be standard procedure. 

CDC Confirms Human Cases of H5 Bird Flu Among Colorado Poultry Workers

Press Release
For Immediate Release: July 14, 2024
Contact: Media Relations
(404) 639-3286


July 14, 2024 – Four human cases of highly pathogenic avian influenza (HPAI) A(H5) (“H5 bird flu”) virus infection in the state of Colorado have been confirmed by the Centers for Disease Control and Prevention (CDC). This includes all three presumptive-positive cases reported by that state on Friday, July 12 and a fourth specimen that was later found to be presumptive-positive by the state on Friday. CDC also is aware of an additional (fifth) presumptive-positive case in Colorado that will be confirmed at CDC once the specimen arrives. All cases were in farm workers who were involved in the depopulation of poultry at a poultry facility experiencing an outbreak of HPAI H5N1 virus. 

A CDC team is on the ground in Colorado, supporting their assessment of the poultry outbreak and associated human cases. Given current information, CDC believes that the risk to the public from this outbreak remains low. These cases again underscore the risk of exposure to infected animals. There are no unexpected increases in flu activity otherwise in Colorado, or in other states affected by H5 bird flu outbreaks in cows and poultry.