A Concerned Scientist @BE@qoto.org

For whatever reason there seems to be a lot of H5N1 science in the news today. Since I haven't been keeping up, here's a bit of a summary of what I've seen.

When the FDA tested milk samples from stores, the original numbers to come out were kind of vague. Eventually they released them all and 20.2% of 297 samples, from 17 states encompassing dairy from 132 processing locations in 17 states were positive for H5N1.

https://www.fda.gov/food/alerts-advisories-safety-information/updates-highly-pathogenic-avian-influenza-hpai#testing

This answered a lot of my early questions. I'd even reached out to an acquaintance who was a purchaser at a grocery chain to try to figure out how milk travelled around the country, but now we have some details. To me, this means the outbreak is a lot bigger than 51 herds in 9 states, which, to be fair, was obvious. But, now that we're talking bigger numbers, let's zoom out to the whole country. There's upwards of 10 million dairy cows in the US. While I am *not* talking about H5N1 being everywhere, I think the possibility exists that we are saying that millions of cows may have been/are infected.

I posted elsewhere today that what we *know* of in terms of spread is mammal to mammal transmission amongst herds of cattle. I do think that accounts for 51 herd in 9 states. However, if we're talking millions of cows, and I'm not sure that we are, we just haven't tested enough to know, then we're likely talking about birds spreading H5N1 across state lines from herd to herd. Unproven, but, keep it on your radar.

Next up, raw milk and pasteurization. Researchers from the Texas A&M Veterinary Medical Diagnostic Laboratory obtained cow’s milk samples from an affected herd in New Mexico.

https://www.nejm.org/doi/full/10.1056/NEJMc2405495#t1

First up, they "orally inoculated" mice with the raw milk. The mice were sick on day 1, and all lived until day 4 at which point they were euthanized and tested. Infection seems to have set in in the pharynx, and led to systemic illness. I don't think that's a surprise, but there you have it. Further, infections were found in the mammary glands, despite the fact that the mice were not lactating. So, similar to cows and their milk, we seem to have an influenza virus with an affinity for mammary glands.

Next, while they are clear that their bench top experiments do not exactly replicate commercial pasteurization processes, they tested heating the milk to 63C and 72C for a variety of times.

All longer times, 5, 10, 20 and 30 minutes at 63C led to no live virus above detection limits.

At 72C, times of 5 seconds and 10 seconds led to detectable amounts of live virus, but 15 seconds did not.

Further tests at 72C for 15, 20 and 30 seconds were inoculated into embryonated chicken eggs or Madin–Darby canine kidney cells for virus detection. These samples showed "educed virus titers by more than 4.5 log units but did not completely inactivate the virus."

One thing I want to highlight here is this:

"The stability of HPAI A(H5N1) virus in cow’s milk stored at 4°C is another important question. For milk sample NM#93, we detected a decline of only two log units over 5 weeks. HPAI A(H5N1) virus may therefore remain infectious for several weeks in raw milk kept at 4°C."

I've leaned towards believing that H5N1 wouldn't survive long term in milk, but, that's why I try to avoid prognosticating as much as I'm able to. I was apparently wrong about that.

So what does all of that mean for milk at the store? I don't know! We'd have to establish an infectious oral dose to know whether what *could* remain after pasteurization, and refrigeration, is significant.

I have other thoughts, but, that's enough of a novel for now!

In terms of institutional support, I was working at a national lab at the time. By rule, I had to disclose to them that I was visited by law enforcement. I did so, explained the whole situation, and no one cared.

https://www.nature.com/articles/d41586-024-01468-9

I'm really glad to see this phenomenon getting some attention, and I'd like to point out that it's nothing new, and it's really not that uncommon, unfortunately. Social media has just made it much easier, and seemingly more acceptable.

A long time ago, back when cameras on phones were new and rare, one day I was home visiting my mom. We noticed a man and a woman going door to door in the neighborhood knocking on doors, filming the neighbors talking. They skipped over our house, and were at another neighbor's house when I went out to my car. They ran over to me, got in my face, and started asking me questions about research I had done that outed a particular polluter of a waterway.

My reaction was....not the best. I wasn't prepared for it at all. I got in my car, started it up, and threatened to run the woman over when she got in front of my car and wouldn't let me leave. I didn't run anyone over, but, I did get a visit from the cops. Thankfully she had relented after a short standoff and let me drive away, and no charges were pressed either direction.

Refer back to this anytime you might wonder why I don't use my name online.