Saturday, July 27, 2024

Minnesota Extension Advice: Do Not Exhibit Lactating Dairy Cows at Public Events Through 2024


Credit CDC 

#18,210

While the spread of HPAI H5 to humans has thus far been restricted (at least in the United States) to agricultural workers, in other parts of the world just strolling through or living near a live bird market has been linked to increased risk of infection (see Open Forum Inf. Dis.: High Prevalence of HPAI Virus In Vietnam's Live Bird Markets).

The standard advice from WHO in countries where HPAI H5 is circulating remains: 

`The public should avoid high-risk environments, such as live animal markets or farms, and avoid contact with live poultry or surfaces that might be contaminated by birds or poultry droppings . . . '.

Similar advice is offered to citizens of Hong Kong who may be traveling to China, where H5N6, H5N1, and several other avian viruses can be found:

Travellers to the Mainland or other affected areas must avoid visiting wet markets, live poultry markets or farms.

This advice is borne of two decades of experience dealing with HPAI.  While the exact route of infection isn't always determined, we've seen studies showing the ambient air at live bird markets can carry detectable virus particles. 

We've even seen evidence that insect vectors, like the common house fly (see Kyushu University: The Return Of The Fly), can become a mechanical transmitter of H5N1 influenza virus.  

The risks from infected livestock (poultry, cows, goats, etc.) - even here in the United States - is a genuine concern.  So much so, that the CDC is currently recommending that farm workers wear PPEs.

Over the past 3 weeks at least 10 farm workers (across 3 American farms) have been infected with HPAI H5N1.  I say `at least' because there are anecdotal reports of symptomatic workers who have refused testing, and because there may be others in the queue. 

Against this backdrop there is a vigorous debate over the risks of allowing agricultural exhibits at state and county fairs, which really kick off in middle America during August & September. 

These range from small local venues to state fairs which attract more than a million visitors. Altogether, it is a multi-billion dollar industry, and these prize animals represent the hard work and dedication of tens of thousands of exhibitors, many of whom are still in school. 

And understandably, nobody wants to be the Grinch who stole the county fair.  

As a result, we've seen a wide range of bio-safety rules promulgated by state and local authorities. Some, like from Michigan and Wisconsin, have been fairly strict.  Others, have been less rigorous, although I would note that yesterday Texas ordered Pre-Movement Testing for Exhibition Dairy Cattle.

We've previously seen the spread of swine-variant influenza viruses to the public through these types of exhibitions (see EID Journal: Shortening Duration of Swine Exhibitions to Reduce Risk for Zoonotic Transmission of Influenza A Virus).  

The CDC has long advised those who are at higher risk of serious flu complications (including children under 5, adults over 65, pregnant women, and those with certain chronic medical conditions), to avoid pigs and the swine barn altogether.

With a new, and potentially more dangerous, HPAI H5 virus now spreading in American livestock, the question becomes, how much risk is acceptable?  And how much faith can we put in the existing (and often inconsistent) biosecurity requirements? 

The risk is more than just to humans, since fairs often bring together poultry, cattle, goats, and pigs.  This `mixed species' environment provides opportunities for the spillover, and spread, of viruses - and potentially - a myriad of reassortment possibilities. 


All of which brings us to a guidance document, issued by the University of Minnesota Extension Office, which calls of the banning of lactating cattle (regardless of testing) from agricultural exhibits until 2025 (and possibility beyond). 

While this would be a bitter pill for many if adopted, the authors warn : `The risk of exposure to H5 influenza for both animals and humans at fairs and exhibitions is high'.

The full report goes into their rationale, and is well worth reading in its entirety.   I'll have a postscript when you return.  


Extension advice: Do not exhibit lactating dairy cows at public events through 2024
July 24, 2024

This article has specific recommendations for animal exhibitions in 2024 in Minnesota due to the outbreak of H5N1 in dairy and poultry operations across the state and country. It also contains information about the spread of influenza A viruses relevant to the general public and people involved in farm animal operations.

Given the high risk posed by lactating dairy cattle to other cattle, the rest of the exhibition community, and the public, lactating dairy cattle should not attend exhibitions including county and state fairs, until 2025 or beyond.

          (Continue . . . )

Short of HPAI H5 suddenly transmitting efficiently in humans, the `next-worse-case' scenario would be for the virus to begin spreading in pigs.  There, it could find a plethora of better-adapted swine flu viruses with which to reassort, substantially increasing the risk of a pandemic. 

While unfortunate for the exhibitors, given the stakes, I find it hard to argue with the advice to exclude lactating cattle from state and county fairs.  Whether these recommendations will be adopted widely, remains to be seen. 

There are, of course, other ways H5N1 might succeed in sparking a pandemic. But given what we know about HPAI, it makes little sense to make it any easier for the virus. 

at